WO2006028159A2

WO2006028159A2 - Reconfigurable circuit-containing electronic device

Info

Publication number: WO2006028159A2
Application number: PCT/JP2005/016478
Authority: WO
Inventors: Yoshiteru Tanaka
Original assignee: Matsushita Electric Industrial Co., Ltd.
Priority date: 2004-09-08
Filing date: 2005-09-01
Publication date: 2006-03-16
Also published as: WO2006028159A3

Abstract

A reconfigurable circuit-containing electronic device including a reconfigurable logic circuit unit (21) operable to reconfigure a logic circuit, a calculation unit (22) operable to calculate a value of permissible electrical power for the reconfigurable logic circuit unit (21), a determination unit (23) operable to determine a circuit specification in accordance with the value of the permissible electrical power and a predetermined initial restriction (25), in which the circuit specification is used to reconfigure the logic circuit in the reconfigurable logic circuit unit (21), and a reconfiguration unit (24) operable to reconfigure the logic circuit in the reconfigurable logic circuit unit (21) in accordance with the circuit specification. The above electronic device is operable to accommodate posterior changes in standard and specification.

Description

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DESCRIPTION

RECONFIGURABLE CIRCUIT-CONTAINING ELECTRONIC DEVICE

Technical Field

The present invention relates to an electronic device that contains a reconfigurable logic circuit unit operable to reconfigure different logic circuits therein and, more particular, to an electronic device operable to reconfigure the different logic circuits in accordance with a value of electrical power permitted to enter the reconfigurable logic circuit unit. Background Art

Recent electronic devices such as portable terminals are constructed to practice complicated processing that is materially changed according to standards of communication systems. For example, in cellular phones, a modulation system as well as an error-correcting system is changed one after another according to a change in standards such as PDC and GSM. As a result, the electronic devices must be modified for each change in standard. In addition, the electronic devices are required to possess a faster processing capability.

Software is susceptible to complicated processing. Accordingly, when a processing method must be changed with a change in standard, such a requirement is met by the replacement of programs.

At the same time, problems with the software are slow processing executed thereby plus the incapability of satisfying required specifications.

Meanwhile, hardware is impossible to cope with variations in standard. To solve the above inconveniences, it has been developed to provide an art that realizes an electronic device provided with a reconfigurable circuit operable to reconfigure different logic circuits, whereby the logic circuits are reconfigured in „

response to a posterior change in standard. Such a reconfigurable logic circuit-containing electronic device allows the different logic circuits to be formed in the reconfigurable logic circuit to accommodate a change in standard. This feature eliminates the need to modify the entire electronic device. According to cited reference No. 1 (published Japanese Patent Application

Laid-Open No. Hl 1-3209), a data-processing apparatus containing a reconfigurable logic circuit is disclosed.

However, as taught by the cited reference No. 1, the logic circuit is reconfigured in a reconfigurable logic circuit unit without regard to logic circuit reconfiguration-caused variations in electrical power consumption of the reconfigurable logic circuit unit.

The reconfiguration of the different logic circuits in the reconfigurable logic circuit unit changes the size and circuit structure of the logic circuit, with consequent variations in electrical power consumption of the reconfigurable logic circuit unit. Since the electronic device can be supplied only with limited power, the variations in power consumption of the reconfigurable logic circuit unit drive the entire electronic device to consume electrical power beyond the range of the permissible supply of the electrical power to the electrical device. This causes a problem that adversely affects the operation of the electronic device. For example, the electronic device is malfunctioned when the electronic device is driven to consume the electrical power greater than the permissible supply of the electrical power thereto as a result of the variations in power consumption of the reconfigurable logic circuit unit.

In particular, the problem is rendered more conspicuous when the reconfigurable logic circuit unit accounts for a large percentage of the inner area space of the electronic device.

Furthermore, to develop the logic circuit in the reconfigurable logic circuit unit, „

a clock frequency and a logic cell size are restricted, but without regard to the entire electronic device. This can be responsible for a greater power consumption of the entire electronic device than the permissible supply of the power thereto, depending upon the logic circuit reconfigured in the reconfigurable logic circuit unit. In view of the above, an object of the present invention is to provide a reconfigurable circuit-containing electronic device operable to calculate a value of permissible electrical power for a reconfigurable logic circuit unit on the basis of electrical power supplied to the entire electronic device, whereby a logic circuit is reconfigured in the reconfigurable logic circuit unit in accordance with a circuit specification based on the permissible electrical power value. Disclosure of the Invention

A first aspect of the present invention provides a reconfigurable circuit-containing electronic device including a reconfigurable logic circuit unit operable to reconfigure a logic circuit, a calculation unit operable to calculate a value of permissible electrical power for the reconfigurable logic circuit unit, a determination unit operable to determine a circuit specification in accordance with the value of the permissible electrical power and a predetermined initial restriction, in which the circuit specification is used to reconfigure the logic circuit in the reconfigurable logic circuit unit, and a reconfiguration unit operable to control the reconfigurable logic circuit unit to reconfigure the logic circuit in accordance with the circuit specification.

The above structure reconfigures the logic circuit in the reconfigurable logic circuit unit within the range of the value of the permissible electrical power permitted to enter the reconfigurable logic circuit unit. As a result, the electrical device according to the present invention is normally operated. A second aspect of the present invention provides a reconfigurable circuit-containing electronic device in which the calculation unit calculates the value of the permissible electrical power in accordance with a value of electrical power supplied _Λ

to the reconfigurable circuit-containing electronic device throughout.

The above structure calculates an appropriate permissible power value for the reconfigurable logic circuit unit.

A third aspect of the present invention provides a reconfigurable circuit-containing electronic device further including a processor operable to control the logic circuit reconfigured in the reconfigurable logic circuit unit. In the reconfigurable circuit-containing electronic device, the calculation unit calculates the value of the permissible electrical power in accordance with a process amount of a program used by the processor. The above structure automatically calculates the permissible power value for the reconfigurable logic circuit unit.

A fourth aspect of the present invention provides a reconfigurable circuit-containing electronic device in which the calculation unit estimates a power consumption value of elements of the reconfigurable circuit-containing electronic device other than the reconfigurable logic circuit unit in accordance with the process amount of the program used by the processor in order to subtract the estimated power consumption value from the value of the electrical power supplied to the reconfigurable circuit-containing electronic device throughout, thereby calculating an electrical power value. As a result, the calculation unit provides the calculated electrical power value as the value of the permissible electrical power.

The above structure automatically calculates the permissible power value for the reconfigurable logic circuit unit. The calculated permissible power value is provided after the supply of the power to the electronic device except for the reconfigurable logic circuit unit is secured. A fifth aspect of the present invention provides a reconfigurable circuit-containing electronic device in which the initial restriction includes at least one of a clock frequency condition, a logic cell size condition, and an operating voltage condition.

The above structure determines circuit specifications in accordance with the factors that determine power consumption in the reconfigurable logic circuit unit. The determined circuit specifications make it feasible to adjust the power consumption in the reconfigurable logic circuit unit.

A sixth aspect of the present invention provides a reconfigurable circuit-containing electronic device in which the determination unit determines at least one of a clock frequency, a logic cell size, and an operating voltage in accordance with the initial restriction in such a manner that the logic circuit reconfigured in the reconfigurable logic circuit unit has a power consumption value equal to or smaller than the value of the permissible electrical power. The clock frequency, logic cell size, and operating voltage are used by the logic circuit.

A seventh aspect of the present invention provides a reconfigurable circuit-containing electronic device in which the determination unit adjusts at least one of values of the clock frequency condition, logic cell size condition, and operating voltage condition from the initial restriction, thereby determining at least one of the clock frequency, logic cell size, and operating voltage as used by the logic circuit.

The above structure reconfigures the logic circuit in the reconfigurable logic circuit unit within the range of the value of the permissible power for the reconfigurable logic circuit unit. An eighth aspect of the present invention provides a reconfigurable circuit-containing electronic device in which when the logic circuit reconfigured in the reconfigurable logic circuit unit in accordance with the clock frequency condition from „

the initial restriction has a power consumption value greater than the value of the permissible electrical power, then the determination unit determines, as the circuit specification, a clock frequency smaller than a clock frequency specified by the clock frequency condition. The above structure reconfigures the logic circuit in the reconfigurable logic circuit unit within the range of the value of the permissible power for the reconfigurable logic circuit unit.

A ninth aspect of the present invention provides a reconfigurable circuit-containing electronic device in which, when the logic circuit reconfigured in the reconfigurable logic circuit unit in accordance with the logic cell size condition from the initial restriction has a power consumption value greater than the value of the permissible electrical power, then the determination unit determines, as the circuit specification, a logic cell size smaller than a logic cell size specified by the logic ell size condition. The above structure reconfigures the logic circuit in the reconfigurable logic circuit unit within the range of the value of the permissible power for the reconfigurable logic circuit unit.

A tenth aspect of the present invention provides a reconfigurable circuit-containing electronic device in which, when the logic circuit reconfigured in the reconfigurable logic circuit unit in accordance with the operating voltage condition from the initial restriction has a power consumption value greater than the value of the permissible electrical power, then the determination unit determines, as the circuit specification, an operating voltage smaller than an operating voltage specified by the operating voltage condition. The above structure reconfigures the logic circuit in the reconfigurable logic circuit unit within the range of the value of the permissible power for the reconfigurable logic circuit unit. An eleventh aspect of the present invention provides a reconfigurable circuit-containing electronic device in which, when the reconfigurable logic circuit unit includes a plurality of devices operated at different operating voltages, then the determination unit determines a logic circuit-reconfiguring device from among the plurality of devices in such a manner that the logic circuit reconfigured in the reconfigurable logic circuit unit has a power consumption value equal to or smaller than the value of the permissible electrical power.

The above structure reconfigures the logic circuit in the reconfigurable logic circuit unit within the range of the value of the permissible power for the reconfigurable logic circuit unit.

The above, and other objects, features and advantages of the present invention will become apparent from the following description read in conjunction with the accompanying drawings, in which like reference numerals designate the same elements.

Brief Description of the Drawings Fig. 1 is a perspective view illustrating an electronic device according to a first embodiment of the present invention;

Fig. 2 is a block diagram illustrating an electronic device according to a second embodiment;

Fig. 3 is a block diagram illustrating an electronic device according to the second embodiment;

Fig. 4 is an illustration showing a change in logic cell according to a third embodiment; and

Fig. 5 is a block diagram illustrating an electronic device according to the third embodiment. Best Mode for Carrying out the Invention

Embodiments of the present invention are now described with reference to the accompanying drawings. First embodiment

Fig. 1 is a perspective view illustrating an electronic device according to a first embodiment of the present invention.

The electronic device 1 may be a wireless communication base station or otherwise a set-top box.

The electronic device 1 has a circuit board 3 disposed within a chassis 2. The circuit board 3 includes a reconfigurable logic circuit unit 4, a processor 6, a memory 7, and a reconfiguration unit 5. The reconfigurable logic circuit unit 4 includes a plurality of reconfigurable semi-conductors 12 such as a field programmable gate array (hereinafter called a "FPGA") and a programmable logic device (hereinafter called a "PLD"). A combination of the reconfigurable semi-conductors 12 reconfigures a variety of logic circuits. At this time, unwanted devices for use in the reconfiguration of the logic circuit in the reconfigurable logic circuit unit 4 need not be built into the electronic device 1 in the presence of the reconfiguration unit 5 incorporated in the electronic device 1. The reconfiguration unit 5 allows any desired logic circuit to be reconfigured in the reconfigurable logic circuit unit 4 when data on the logic circuit reconfigured in the reconfigurable logic circuit unit 4 are supplied to the electronic device 1 from the outside thereof.

The electronic device 1 includes an antenna 8, a display unit 9, a control unit 10, and a battery 11, thereby serving a display function as well as a wireless communication function. The display unit 9 is formed by liquid crystal. The control unit

10 is formed with a switch and a keyboard. The electronic device 1 fulfills a variety of functions in the presence of the control unit 10 and display unit 9.

For example, data received by the antenna 8 are demodulated by the logic circuit in the reconfigurable logic circuit unit 4, thereby displaying images on the display unit 9. More specifically, the electronic device 1 is used as a receiver and a set-top box. Alternatively, signals from the control unit 10 are demodulated by the logic circuit in the reconfϊgurable logic circuit unit 4, thereby emitting the demodulated signals into surroundings. More specifically, the electronic device 1 is used as a wireless communication apparatus.

Thus, the electronic device 1 provided with the reconfigurable logic circuit unit 4 and reconfiguration unit 5 is used as electronic equipment operable to satisfy various specifications.

The electronic device 1 of Fig. 1 is one of examples of electronic devices, and broadly includes electronic devices contained in and out of the chassis 2, and those combined with other electric equipment. When the electronic device 1 is driven by the battery 11 , loads on the battery 11 are varied according to the size and operation of the logic circuit reconfigured in the reconfigurable logic circuit unit 4.

Even when the specification of the logic circuit must be changed according to a change in standard, the electronic device 1 is operable to cope with the change in the presence of a reconfigurable circuit or rather the reconfigurable logic circuit unit 4. Accordingly, the electronic device 1 is employed in a variety of systems.

For example, the electronic device 1 is applied to cellar phone base stations. Cellular phones involve a large number of standards such as PDC, GSM, and AMPS. The standards are changed according to situations such as places and time. For example, a PDC-adapted logic circuit instead of a GSM-adapted one is reconfigured in the reconfigurable logic circuit unit 4 in response to a change in standard from GSM to PDC. The built-in reconfigurable logic circuit unit 4 readily meets a posterior change in specification, with a consequential reduction in cost of the entire system.

Alternatively, the electronic device 1 may be applied to a TV and video equipment. For example, a logic circuit responsive to a changed encoding system is reconfigured in the reconfϊgurable logic circuit unit 4 in response to a change in image-encoding system. As a further alternative, the electronic device 1 is preferably applied to a car navigation system.

In addition, the electronic device 1 may be applied to cellular phones and portable terminals. Similar to the base stations, for the cellular phones and portable terminals, standards are changed according to situations such as places and time. The reconfigurable logic circuit unit 4 allows the electronic device 1 to appropriately meet such a change in standard. In particular, the cellular phones and portable terminals are used at various places over the world, and are consequently required to conform to a large number of standards. In light of downsizing and power consumption, a single cellular phone and a single portable terminal are difficult to satisfy all of the standards. Cellular phones and portable terminals employing the electronic device 1, provided with minimum functions and the reconfigurable logic circuit unit 4, can be used after having different logic circuits according to required specifications reconfigured therein. Accordingly, every cellular phone using the electronic device 1 is operable to switch over between PDC and GSM systems, depending upon places and time.

Alternatively, only a logic circuit that conforms to specifications uncommon to both of the PDC and GSM systems may be reconfigured in the reconfigurable logic circuit unit 4. The electronic device 1 is in widespread use in other electronic equipment as well as the above-described electric equipment.

The electronic device 1 includes an element operable to determine a circuit specification that is used when the reconfiguration unit 5 reconfigures the logic circuit.

The circuit specification is determined by a value of permissible electrical power permitted to enter into the reconfigurable logic circuit unit 4, and a predetermined initial restriction that is used when the logic circuit is reconfigured. The initial restriction includes restriction conditions such as clock frequency conditions, which are usually used to reconfigure the logic circuit in the reconfϊgurable logic circuit unit 4.

The electronic device 1 is supplied with a predetermined value of electrical power, and a power consumption value in the electronic device 1 is varied according to the size and constitution of the logic circuit that is reconfigured in response to a change in specification. At the same time, the power consumption of elements of the electronic device 1 other than the reconfigurable logic circuit 4 having control of the reconfigured logic circuit is varied as well, and the value of the permissible electrical power permitted to enter the reconfigurable logic circuit unit 4 is varied accordingly.

Accordingly, the permissible electrical power value must be taken into account when the logic circuit is reconfigured in the reconfigurable logic circuit unit 4. The circuit specification for use in the logic circuit reconfiguration is determined based on the permissible electrical power value.

The reconfiguration unit 5 reconfigures the logic circuit in the reconfigurable logic circuit unit 4 in accordance with the determined circuit specification. As discussed above, the electronic device 1 is operated within the range of a value of supplied electrical power, and is flexibly responsive to a posterior change in specification.

Second embodiment A second embodiment is now described. Fig. 2 is a block diagram illustrating an electronic device according to the present embodiment.

The electronic device 20 includes a reconfigurable circuit. A reconfigurable logic circuit unit 21 is a block corresponding to the reconfigurable circuit.

Each element is now described. The reconfigurable logic circuit unit 21 is a circuit block in which different logic circuits are reconfigurable. The circuit block is formed by a PLD or FPGA. The reconfigurable logic circuit unit 21 may include singular or otherwise plural devices J- -ώ

such as the FPGA, and required peripheral circuits. As well known, the FPGA and PLD allow the posterior reconfiguration of different logic circuits.

Part of the device such as the FPGA may include a non-configurable macro block. The following discusses a calculation unit 22.

The calculation unit 22 is operable to calculate a value of permissible electrical power permitted to enter the reconfigurable logic circuit unit 21. A value of electrical power consumed inside and around the reconfigurable logic circuit unit 21 is varied according to the size and processing of the logic circuit reconfigured in the reconfigurable logic circuit unit 21. A value of electrical power supplied to the electronic device 20 has an upper limit, and the value of the permissible electrical power for the reconfigurable logic circuit unit 21 has an upper limit as well. The permissible electrical power value is varied for each event of the logic circuit reconfiguration.

The calculation unit 22 is operable to calculate such a variable value of the permissible power on the basis of the value of the electrical power supplied to the entire electronic device 20.

For example, referring to Fig. 3, the electronic device 20 is shown including a processor 27, and the calculation unit 22 calculates the permissible power value using the processor 27. Fig. 3 is a block diagram illustrating the electronic device according to the present embodiment.

The processor 27 has control of the entire electronic device 20. This means that the processor 27 also has control of the logic circuit reconfigured in the reconfigurable logic circuit unit 21. To this end, the processor 27 stores a program for control over the reconfigured logic circuit. A value of power consumption required by the processor 27 and peripheral circuits thereof is estimated by the calculation unit 22 based on a process amount of the program. The estimated power consumption value of the processor 27 and peripheral circuits thereof is a power consumption value in the electronic device 20 XO

except for the reconfϊgurable logic circuit unit 21. Accordingly, the calculation unit 22 subtracts the estimated power consumption value as just discussed from the value of the power supplied to the entire electronic device 20, thereby calculating the value of the permissible power for the reconfϊgurable logic circuit unit 21. The process amount of the program used by the processor 27 is varied according to the reconfigured logic circuit, and the calculation unit 22 estimates a required program process amount on the basis of logic circuit data 26 used by the reconfiguration unit 24.

As discussed above, the electronic device 20 automatically calculates the value of the permissible power for the reconfϊgurable logic circuit unit 21. The following discusses a determination unit 23.

A circuit specification is used to reconfigure the logic circuit. The determination unit 23 is operable to determine the circuit specification on the basis of a predetermined initial restriction 25 and the permissible power value calculated by the calculation unit 22. The predetermined initial restriction 25 is provided to the determination unit 23 when the logic circuit is reconfigured. The determination unit 23 feeds the determined circuit specification into the reconfiguration unit 24.

The determined circuit specification includes a variety of specifications required to reconfigure the logic circuit in the reconfϊgurable logic circuit unit 21. In particular, the determined circuit specification includes specifications required to provide a reconfigured logic circuit having a power consumption value equal to or smaller than the permissible power value.

Accordingly, "clock frequency", "logic cell size", and "operating voltage" are particularly important specifications, which can be parameters that determine the power consumption value.

Similarly, the initial restriction 25 includes a variety of specifications required for the logic circuit reconfiguration. In particular, the initial restriction 25 includes at least "clock frequency conditions", "logic cell size conditions", and "operating voltage conditions", all of which are required to determine the circuit specification. The initial restriction 25 is provided to the electronic device 20, together with the logic circuit data 26, when the logic circuit is reconfigured. The initial restriction 25 may be determined by users or otherwise may be generated in response to the generation of logic circuit data 26.

The determination unit 23 determines at least one of the "clock frequency", "logic cell size, and "operating voltage" as at least one of the circuit specifications in accordance with the "clock frequency conditions", "logic cell size conditions", and "operating voltage conditions" from the initial restriction 25, and the permitted voltage value. The "clock frequency", "logic cell size, and "operating voltage" are used when the logic circuit is reconfigured.

At this time, the circuit specifications as just discussed are determined in such a manner that the logic circuit reconfigured according to the above circuit specifications has a power consumption value equal to or smaller than the permissible power value. In particular, the determination unit 23 adjusts at least one of values of the "clock frequency conditions", "logic cell size conditions", and "operating voltage conditions" from the initial restriction 25 in such a manner that the reconfigured logic circuit has a power consumption value equal to or smaller than the permissible power value. Thereafter, the reconfiguration unit 24 reconfigures a desired logic circuit in the reconfigurable logic circuit unit 21 in accordance with the logic circuit data 26 and the circuit specification received from the determination unit 23. The logic circuit data 26 illustrates a circuit structure of the logic circuit.

As described above, the circuit specification determined by the determination unit 23 is used to reconfigure the logic circuit, and eventually the logic circuit reconfigured in the reconfigurable logic circuit unit 21 has a power consumption value equal to or smaller than the permissible power value. Third embodiment

A third embodiment is now described.

In the electronic device 20, the determination unit 23 adjusts at least one of the "clock frequency conditions", "logic cell size conditions", and "operating voltage conditions" from the initial restriction 25 to provide a reconfigured logic circuit having a power consumption value equal to or smaller than the permissible power value, thereby determining circuit specifications. The determined circuit specifications are sent to the reconfiguration unit 24.

The present embodiment discusses the way of determining the circuit specification in detail.

The determination unit 23 determines a clock frequency as one of the circuit specifications.

The determination unit 23 receives the "clock frequency conditions" from the initial restriction 25 and the permissible power value from the calculation unit 22. In addition, the determination unit 23 receives the logic circuit data 26, thereby recognizing information on the circuit structure and size of the logic circuit.

Thereafter, the determination unit 23 estimates, on the basis of the logic circuit data 26 and the clock frequency conditions, a power consumption value of the logic circuit reconfigured in the reconfϊgurable logic circuit unit 21. The determination unit 23 compares the estimated power consumption value with the permissible power value calculated by the calculation unit 22. When the estimated power consumption value is equal to or smaller than the permissible power value, then the determination unit 23 determines, as one of the circuit specifications, a clock frequency specified by the clock frequency conditions from the initial restriction 25. Conversely, when the estimated power consumption value is greater than the permissible power value, then the determination unit 23 determines, as one of the circuit specifications, a clock frequency smaller than the specified clock frequency as just discussed. For example, with the specified clock frequency of 25 MHz, the determination unit 23 determines the 20 MHz clock frequency as one of the circuit specifications.

In general, the power consumption value of the logic circuit increases in proportion to the clock frequency, and decreases with a reduction in clock frequency. As a result, the logic circuit reconfigured in the reconfigurable logic circuit unit has a power consumption value equal to or smaller than the permissible power value, and prevents the malfunction of the electronic device.

The determination unit 23 determines an optimal clock frequency while estimating a power consumption value of the logic circuit for each change in clock frequency in the adjustment of the clock frequency. For example, assume that 25 MHz is specified by the clock frequency conditions, and that a power consumption value at the 25 MHz clock frequency is greater than the permissible power value. The determination unit 23 initially estimates a power consumption value at the 23 MHz clock frequency to compare the estimated power consumption value with the permissible power value. When the estimated power consumption value at the 23 MHz clock frequency is still greater than the permissible power value, then the determination unit 23 estimates a power consumption value at 20 MHz clock frequency. When the estimated power consumption value at 20 MHz is equal to or smaller than the permissible power value, then the determination unit 23 determines the 20 MHz clock frequency as the circuit specification. Alternatively, the determination unit 23 may estimate power consumption values at 21 MHz or otherwise 22 MHz clock frequencies to search for the most limited clock frequency at which the estimated power consumption value is smaller than the permissible power value, whereby the searched clock frequency is determined as the circuit specification.

Next, the determination unit 23 determines a logic cell size as one of the circuit specifications. The determination unit 23 receives the "logic cell size conditions" from the initial restriction 25 and the permissible power value from the calculation unit 22. Similarly, the determination unit 23 receives the logic circuit data 26.

The determination unit 23 initially estimates a power consumption value of the logic circuit reconfigured in the reconfigurable logic circuit unit 21, on the basis of the logic circuit data 26 and a logic cell size specified by the logic cell size conditions. The determination unit 23 then compares the estimated power consumption value with the permissible power value. When the estimated power consumption value is equal to or smaller than the permissible power value, then the determination unit 23 determines the specified logic cell size as one of the circuit specifications.

Conversely, when the estimated power consumption value is greater than the permissible power value, then the determination unit 23 determines a logic cell size smaller than the specified logic cell size as one of the circuit specifications. Fig. 4 illustrates a change in logic cell size. Fig. 4 is an illustration showing the change in logic cell size according to the present embodiment. As shown in Fig. 4, "ANDl", "AND2", and "ORl" are changed to render logic cell sizes thereof smaller.

The smaller logic cell size results in a smaller load capacity, with a consequent reduction in power consumption value. Eventually, the power consumption value is equal to or smaller than the permissible power value.

For example, logic cell size-related groups may be set up in advance to designate any group equal to or smaller than the estimated power consumption value.

Next, the determination unit 23 determines an operating voltage as one of the circuit specifications. The determination unit 23 receives the operating voltage conditions from the initial restriction 25, the permissible power value calculated by the calculation unit 22, and the logic circuit data 26. The determination unit 23 estimates, based on them, a power consumption value of the logic circuit reconfigured in the reconfigurable logic circuit unit 21.

The determination unit 23 compares the estimated power consumption value with the permissible power value. When the comparison shows that the estimated power consumption value is equal to or smaller than the permissible power value, then the determination unit 23 determines, as one of the circuit specifications, an operating voltage specified by the operating voltage conditions from the initial restriction 25.

When the comparison shows that the estimated power consumption value is greater than the permissible power value, then the determination unit 23 determines an operating voltage smaller than the specified operating voltage as one of the circuit specifications. For example, when the specified operating is 5 V, then the determination unit 23 determines 3.3 V as the circuit specification. The power consumption value of the logic circuit usually increases in proportion to the second power of the operating voltage, and a reduction in operating voltage reduces the power consumption value. Alternatively, the determination unit 23 may search for an optimal operating voltage while estimating a power consumption value accompanied by a reduction in operating voltage, whereby an ultimately determined operating voltage is provided.

As a further alternative, the determination unit 23 may determine each of adjusted clock frequency, logic cell size, and operating voltage as one of the circuit specifications, or otherwise may determine a proper combination of the adjusted clock frequency, logic cell size, and operating voltage as the circuit specifications. For example, the determination unit 23 may determine both of the adjusted clock frequency and operating voltage as the circuit specifications in such a manner that the logic circuit has a power consumption value equal to or smaller than the permissible power value. The following discusses, with reference to Fig. 5, a different adjustment made by the determination unit 23.

Fig. 5 is a block diagram illustrating the electronic device according to the present embodiment.

The reconfϊgurable logic circuit unit 21 includes a plurality of devices 30 operated at different operating voltages. Each of the devices 30 may be a PLD or otherwise a FPGA. As illustrated in Fig. 5, the devices 30 have different operating voltages, e.g., such as 5 V, 3.3 V, and 2.5 V. The operating voltages are offered merely by way of illustration, and are not limited thereto. The devices 30 may be a plurality of PLDs or FPGAs having the same or different operating voltages.

In general, each of the devices 30 that reconfigure the logic circuit has a power consumption value increasing in proportion to the square of the operating voltage, and a reduction in operating voltage operatively reduces the power consumption value.

The determination unit 23 estimates a power consumption value of the logic circuit reconfigured in the reconfigurable logic circuit unit 21, on the basis of the logic circuit data 26 and the operating voltage specified by the operating voltage conditions from the initial restriction 25. Thereafter, the determination unit 23 compares the estimated power consumption value with the permissible power value calculated by the calculation unit 22. When the estimated power consumption value is equal to or smaller than the permissible power value, then the determination unit 23 selects any device(s)

30 having an operating voltage corresponding to the specified operating voltage as just discussed, thereby determining the selected device(s) 30 as the circuit specification.

When the estimated power consumption value is greater than the permissible power value, then the determination unit 23 selects any device(s) 30 having an operating voltage less than the specified operating voltage, thereby determining the selected device(s) 30 as the circuit specification. At this time, a power consumption value at the selected operating voltage is again estimated to compare the estimated power consumption value with the permissible power value. Such a process is repeated to select any device(s) 30 having the most appropriate operating voltage among operating 2

voltages at which the power consumption value is less than the permissible power value.

The clock frequency and logic cell size as well as the selected devices 30 having different operating voltages may be determined as the circuit specifications. A variety of elements mixed together are determined as the circuit specifications, and optimal circuit specifications equal to or less than the permissible power value are determined.

For example, when it is estimated that the logic circuit reconfigured in the reconfigurable logic circuit unit 21 according to the initial restriction 25 has a very high power consumption value, then both of the operating voltage and the clock frequency are desirably reduced. In addition, the logic cell size is still desirably made smaller.

The clock frequency, logic cell size, and operating voltage are only an example of the circuit specifications to adjust the power consumption value, and the determination unit 23 may determine other parameters as the circuit specifications. As described above, the reconfigurable circuit-containing electronic device according to the present invention has the logic circuit reconfigured within the range of a value of the permissible electrical power permitted to enter the reconfigurable logic circuit unit. As a result, the electronic device according to the present invention is normally operated without an interruption in the supply of required electrical power to the entire electronic device.

Pursuant to the present invention, the logic circuit is reconfigured in the reconfigurable logic circuit unit within the range of the value of the permissible power permitted to enter the reconfigurable logic circuit unit. As a result, the electronic device according to the present invention is normally operated without an interruption in the supply of required electrical power to the entire electronic device.

The permissible power value is automatically calculated based on the process amount of program data, and accordingly designers are relieved of undue care. In addition, manual operation-caused errors are prevented.

. To adjust the power consumption value, the determination unit determines at least one of the clock frequency, logic cell size, and operating voltage as one of the circuit specifications in accordance with the initial restriction, and accordingly the power consumption value is readily and positively made equal to or smaller than the permissible power value.

Industrial Applicability

The present invention finds desirable applications in the field of, e.g., setting-type and portable electronic devices whose standards may often be changed. Having described preferred embodiments of the invention with reference to the accompanying drawings, it is to be understood that the invention is not limited to those precise embodiments, and that various changes and modifications may be effected therein by one skilled in the art without departing from the scope or spirit of the invention as defined in the appended claims.

Claims

1. A reconfϊgurable circuit-containing electronic device comprising: a reconfigurable logic circuit unit operable to reconfigure a logic circuit; a calculation unit operable to calculate a value of permissible electrical power for said reconfigurable logic circuit unit; a determination unit operable to determine a circuit specification in accordance with the value of the permissible electrical power and a predetermined initial restriction, the circuit specification being used to reconfigure the logic circuit in said reconfigurable logic circuit unit; and a reconfiguration unit operable to control said reconfigurable logic circuit unit to reconfigure the logic circuit in accordance with the circuit specification.

2. A reconfigurable circuit-containing electronic device as defined in claim 1, wherein said calculation unit calculates the value of the permissible electrical power in accordance with a value of electrical power supplied to said reconfigurable circuit-containing electronic device throughout.

3. A reconfigurable circuit-containing electronic device as defined in claim 1, further comprising: a processor operable to control the logic circuit reconfigured in said reconfϊgurable logic circuit unit, and wherein said calculation unit calculates the value of the permissible electrical power in accordance with a process amount of a program used by said processor.

4. A reconfigurable circuit-containing electronic device as defined in claim 3, wherein said calculation unit estimates a power consumption value of elements of said reconfigurable circuit-containing electronic device other than said reconfigurable logic circuit unit in accordance with the process amount of the program used by said processor in order to subtract the estimated power consumption value from the value of ^

the electrical power supplied to said reconfϊgurable circuit-containing electronic device throughout, thereby calculating an electrical power value, whereby said calculation unit provides the calculated electrical power value as the value of the permissible electrical power.

5. A reconfϊgurable circuit-containing electronic device as defined in claim 1, wherein the initial restriction comprises at least one of a clock frequency condition, a logic cell size condition, and an operating voltage condition.

6. A reconfϊgurable circuit-containing electronic device as defined in claim 5, wherein said determination unit determines at least one of a clock frequency, a logic cell size, and an operating voltage in accordance with the initial restriction in such a manner that the logic circuit reconfigured in said reconfϊgurable logic circuit unit has a power consumption value at most equal to the value of the permissible electrical power, the clock frequency, logic cell size, and operating voltage being used by the logic circuit.

7. A reconfigurable circuit-containing electronic device as defined in claim 6, wherein said determination unit adjusts at least one of values of the clock frequency condition, logic cell size condition, and operating voltage condition from the initial restriction, thereby determining at least one of the clock frequency, logic cell size, and operating voltage as used by the logic circuit.

8. A reconfigurable circuit-containing electronic device as defined in claim 7, wherein when the logic circuit reconfigured in said reconfigurable logic circuit unit in accordance with the clock frequency condition from the initial restriction has a power consumption value greater than the value of the permissible electrical power, then said determination unit determines, as the circuit specification, a clock frequency smaller than a clock frequency specified by the clock frequency condition.

9. A reconfigurable circuit-containing electronic device as defined in claim 7, wherein when the logic circuit reconfigured in said reconfigurable logic circuit unit in accordance with the logic cell size condition from the initial restriction has a power consumption value greater than the value of the permissible electrical power, then said determination unit determines, as the circuit specification, a logic cell size smaller than a logic cell size specified by the logic ell size condition.

10. A reconfigurable circuit-containing electronic device as defined in claim 7, wherein when the logic circuit reconfigured in said reconfigurable logic circuit unit in accordance with the operating voltage condition from the initial restriction has a power consumption value greater than the value of the permissible electrical power, then said determination unit determines, as the circuit specification, an operating voltage smaller than an operating voltage specified by the operating voltage condition.

11. A reconfigurable circuit-containing electronic device as defined in claim

1, wherein when said reconfigurable logic circuit unit comprises a plurality of devices operated at different operating voltages, then said determination unit determines a logic circuit-reconfiguring device from among the plurality of devices in such a manner that the logic circuit reconfigured in said reconfigurable logic circuit unit has a power consumption value at most equal to the value of the permissible electrical power.

12. A reconfigurable circuit-containing electronic device as defined in claim 1, wherein said reconfigurable logic circuit unit comprises at least one of a PLD and a FPGA.