JP5704669B2 - Semiconductor device - Google Patents

Description

  The present invention relates to a technology for reducing power consumption of a semiconductor integrated circuit, for example, a data processing semiconductor integrated circuit in which a CPU (central processing unit) and its peripheral circuits are formed on a single semiconductor chip, particularly a battery. The present invention relates to a technique effective for use in a semiconductor integrated circuit used in a portable electronic device that operates.

  2. Description of the Related Art Conventionally, in a standby mode or the like, there is a semiconductor integrated circuit such as a microcomputer in which the operation of a circuit is stopped by stopping a clock signal while supplying a power supply voltage to the entire chip to reduce power consumption.

  However, in this method of reducing power consumption by stopping the clock, the operation is stopped while the power supply voltage is supplied to the chip. Therefore, if there is a leakage current in the MOSFET constituting the circuit, the power consumption is sufficient. There is a problem that it is not reduced. On the other hand, some semiconductor integrated circuits may operate other circuits without operating some circuits inside the chip. In such a case, it is conceivable to cut off the supply of the power supply voltage to a circuit that does not need to be operated.

  If the supply of power supply voltage to a circuit block that does not need to be operated by dividing the inside of the chip into multiple circuit blocks is cut off, power consumption can be reduced, but the circuit block in which the power supply is cut off The state of the signal output from becomes unstable. Therefore, if the circuit block on the side receiving such a signal is operating, the circuit may malfunction.

  In view of this, the present inventors have studied a method in which an interface circuit is provided in each circuit block, and a signal input from a circuit block in which supply of power supply voltage is cut off is cut off by the interface circuit.

  However, with this method, the design of the circuit block to which the interface circuit is to be provided needs to be changed, and the change must be made in consideration of the state of other circuit blocks, so the design is very complicated. Become. In addition, it is necessary to add an interface circuit for each signal supplied from the circuit block from which the supply of power supply voltage is cut off, so that it is clear that there is a problem that the circuit area increases and the chip size increases. became.

  An object of the present invention is to provide a semiconductor integrated circuit technology that can reduce power consumption by cutting off the power supply voltage of some circuits while preventing malfunction of the circuits.

  Another object of the present invention is to provide a semiconductor integrated circuit technology capable of reducing power consumption while suppressing an increase in circuit area.

  Another object of the present invention is to provide a semiconductor integrated circuit technology capable of reducing power consumption by adding a few circuits.

  The above and other objects and novel features of the present invention will be apparent from the description of this specification and the accompanying drawings.

  Outlines of representative ones of the inventions disclosed in the present application will be described as follows.

  In other words, the inside of the chip is divided into a plurality of circuit blocks, and one of the circuit blocks is configured such that the power supply voltage is cut off and the operation can be stopped, and between the circuit block that can stop the operation and another circuit block In addition, an inter-block interface circuit (hereinafter simply referred to as an interface circuit) including a signal gate means capable of interrupting signal transmission and a storage means capable of storing a signal state immediately before power-off is provided. . Here, the interface circuit is preferably provided at a position on a path of a signal output from a circuit block capable of stopping operation to another circuit block before the signal is branched.

  According to the above-described means, the power supply voltage of some circuit blocks can be cut off in a state where the signal immediately before the power cut-off is stored, so that power consumption can be reduced while preventing malfunction of the circuit block on the signal receiving side. it can. Further, since the interface circuit is provided between the circuit blocks rather than within the circuit block on the signal receiving side, the circuit block does not need to be changed, and power consumption can be reduced by adding or changing a relatively small number of circuits.

  In addition, if an interface circuit is provided at the input of a circuit block that receives a signal from a circuit block that stops operating when the power is cut off, if the number of fanouts of that signal is large, that number of interface circuits is required. However, the number of interface circuits can be reduced by providing an interface circuit at a position on the path of a signal output from a circuit block capable of interrupting the supply of power supply voltage to another circuit block before the signal is branched. As a result, the power consumption can be reduced while suppressing an increase in circuit area.

  Preferably, the interface circuit includes a comparison circuit for comparing the signal stored in the storage means and the signal output from the circuit block after restarting the power supply to the circuit block whose power is cut off. Provide. As a result, when the power supply to the circuit block whose power has been cut off is resumed, the signal gate means in the interface circuit is brought into a signal transmittable state after confirming that the original state has been restored. As a result, it is possible to prevent the circuit from malfunctioning after the power is restored.

  The effects obtained by the representative ones of the inventions disclosed in the present application will be briefly described as follows.

  That is, according to the present invention, the power supply voltage of some circuit blocks can be shut off in a state in which the signal immediately before the power cut-off is stored, so that power consumption can be reduced while preventing malfunction of the circuit block on the signal receiving side. it can. Further, since the interface circuit is provided between the circuit blocks, it is not necessary to change the circuit block, and power consumption can be reduced by adding or changing a few circuits. Furthermore, the number of interface circuits can be minimized by providing an interface circuit on a path of a signal output from a circuit block capable of shutting off the power supply to another circuit block before the signal is branched. As a result, power consumption can be reduced while suppressing an increase in circuit area.

1 is a block diagram showing a schematic configuration of a first embodiment of a semiconductor integrated circuit to which the present invention is applied. 3 is a flowchart showing a procedure of power-off to a part of circuit blocks and a power-return operation in the semiconductor integrated circuit according to the embodiment. 6 is a timing chart illustrating timings of related signals when power is cut off in some circuit blocks in the semiconductor integrated circuit according to the embodiment. 6 is a timing chart illustrating timings of related signals when power is restored in some circuit blocks in the semiconductor integrated circuit according to the embodiment. It is a block diagram which shows schematic structure of 2nd Example of the semiconductor integrated circuit to which this invention is applied. It is a block diagram which shows the schematic structure of the 3rd Example of the semiconductor integrated circuit to which this invention is applied, and the structural example of the mobile telephone system which used this as a control apparatus. It is a block diagram which shows an example of the relationship between the interface circuit in an Example, and the input / output circuit of an I / O part. It is a block diagram which shows schematic structure of 4th Example of the semiconductor integrated circuit to which this invention is applied.

  Preferred embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 shows a schematic configuration of a first embodiment of a semiconductor integrated circuit to which the present invention is applied. In FIG. 1, reference numeral 10 denotes one semiconductor chip such as single crystal silicon. As shown in FIG. 1, in the semiconductor integrated circuit of this embodiment, the inside of the chip is divided into a plurality of circuit blocks 11, 12, 13,. In this embodiment, among these circuit blocks, the circuit block 11 is a circuit block whose operation can be stopped.

  Reference numeral 21 denotes an external power supply terminal to which a power supply voltage Vcc supplied from the outside is applied. On the power supply line 22 that supplies the power supply voltage from the power supply terminal 21 to the circuit block 11, a power supply switch 23 that can cut off the supply of power is provided. Further, an interface circuit 30 is provided on the path of the signal DT output from the circuit block 11 to the other circuit blocks 12, 13,... Although FIG. 1 shows an example in which the wiring is branched, a buffer or a logic gate having a plurality of fan-outs may be arranged at the branch point N to branch the signal.

  In general, in a semiconductor integrated circuit, there is a case where a signal is branched not only in one place but in a so-called tree structure in which branches gradually occur. In such a case, the interface circuit 30 is provided between the second stage and the third stage. May be provided respectively. However, in terms of number, it is most desirable to provide the interface circuit 30 before the branch point close to the circuit block 11 on the output side.

  Although only one interface circuit is shown in FIG. 1, a similar interface circuit is also provided on the path of other signals (not shown) output from the circuit block 11 to the other circuit blocks 12, 13,. 30 is provided. In this embodiment, although not particularly limited, control signals CS1 and CS2 for receiving the power cutoff request signal PCQ from the circuit block 11 to turn off the power switch 23 and to control the interface circuit 30. Is provided on the same chip.

  The interface circuit 30 can store a signal gate means 31 that enables or interrupts transmission of a signal such as a switch or a logic gate made of a MOSFET, for example, and a signal state (high level or low level) immediately before power-off. Storage means 32 and a signal comparison circuit 33 for comparing the data signal DT ′ stored in the storage means 32 with the data signal DT output after the power supply is resumed from the circuit block where the power supply is cut off. Has been. The comparison result signal CD of the signal comparison circuit 33 is supplied to the inter-block signal control circuit 40. The storage means 32 can be constituted by a flip-flop or the like, and the signal comparison circuit 33 can be constituted by an exclusive NOR gate or the like.

  According to this embodiment, since the power supply voltage of some circuit blocks 11 can be cut off in a state where the signal immediately before the power cut-off is stored, the stored signal continues to be supplied even after the cut-off. Therefore, power consumption can be reduced while preventing malfunction of the circuit blocks 12 and 13 on the signal receiving side. Further, according to this embodiment, as shown in FIG. 1, the interface circuit 30 is provided on the side close to the output terminal of the circuit block 11 where the power is cut off. That is, when the signal output from the circuit block 11 is supplied to a plurality of circuit blocks, the interface circuit 30 is provided in front of the branch point N where the signal is branched. , 13... Can be reduced in number compared to the case where an interface circuit is provided at the entrance.

  Next, the procedure of shutting off the power to the circuit block 11 and the power recovery operation in the semiconductor integrated circuit of the embodiment of FIG. 1 will be described using the flowchart of FIG. 2 and the timing charts of FIGS.

  If, for example, an operation stop mode occurs in the circuit block 11 during normal operation (step S1), the value of the register in the circuit block 11 is transferred to and stored in a memory outside the chip, for example (step S2). ). If there are memories in other circuit blocks 12 and 13, they may be saved there. In this case, the interface circuit 30 as described above is not provided on the signal path.

  Thereafter, the circuit block 11 asserts the power shutdown request signal PCQ to, for example, a high level to notify the inter-block signal control circuit 40 of the power shutdown (step S3 in FIG. 2 and timing t1 in FIG. 3). Then, the inter-block signal control circuit 40 changes the control signal CS2 to, for example, a low level to change the signal gate means 31 in the interface circuit 30 to the cutoff state (step S4 in FIG. 2 and timing t2 in FIG. 3).

  When the signal gate unit 31 is turned off, the state immediately before the signal DT output from the circuit block 11 is stored in the storage unit 32. Subsequently, the inter-block signal control circuit 40 changes the control signal CS1 to turn off the power switch 23 (step S5 in FIG. 2 and timing t3 in FIG. 3).

  The above is the control when the power is shut off. By this control, the state of the data signal DT output from the circuit block 11 becomes indefinite, but since it is stored in the storage means 32 before that and continues to be supplied even after being shut off, another circuit block that receives this data signal DT ′. 12, 13, etc. will not malfunction.

  The power recovery is started by asserting the power-on request signal POQ of the circuit block 11 to the inter-block signal control circuit 40 (step S6). The power-on request signal POQ may be input from the outside of the chip, or may be input from another circuit block 12, 13 or the like. When the power-on request signal POQ is asserted, the inter-block signal control circuit 40 changes the control signal CS1 to high level to turn on the power switch 23 and supplies the power supply voltage Vcc to the circuit block 11 (FIG. 2). Step S7, timing t4 in FIG.

  Then, in the circuit block 11, internal registers and the like are initialized. Subsequently, the circuit block 11 returns the value of the register saved in the memory outside the chip (or the memory in another circuit block 12 or 13) to the original register (step S8). As a result, the data signal DT output from the circuit block 11 immediately before the power is turned off returns to the original state. Further, the power cutoff request signal PCQ to the inter-block signal control circuit 40 is also negated to a low level.

  Thereafter, the inter-block signal control circuit 40 checks the comparison result signal CD from the comparison circuit 33 in the interface circuit 30, and the data signal DT output from the circuit block 11 and the data signal stored in the storage means 32. It is determined whether or not the states of DT ′ are the same. If they are not the same, the process returns to step S7 to reinitialize the circuit block 11 or perform a predetermined error and processing (steps S9 and S10).

  On the other hand, when the data signals DT and DT ′ coincide with each other, the comparison result signal CD changes to the high level as shown in the timing t5 in FIG. 4, and accordingly, the inter-block signal control circuit 40 sets the control signal CS2 to the high level. The signal gate means 31 in the interface circuit 30 is turned on by changing the level (step S11 in FIG. 2, timing t6 in FIG. 4). As a result, the circuit block 11 is connected to the other circuit blocks 12 and 13, and the chip returns to normal operation.

  The embodiment in which the inter-block signal control circuit 40 controls the power cutoff to the circuit block 11 has been described above. However, the power of the circuit block 11 is supplied from the outside separately from other circuit blocks. Therefore, the present invention can also be applied to an embodiment in which the power supply to the circuit block 11 is externally cut off.

  Next, a second embodiment of the present invention will be described with reference to FIG. In FIG. 5, the same circuits and parts as those in FIG. Reference numeral 50 denotes an external power supply device.

  In the second embodiment, power switches 23A, 23B, and 23C are provided so that the supply of power to the plurality of circuit blocks 11, 12, and 13 on the semiconductor chip 10 can be cut off. Although not particularly limited around the circuit blocks 11, 12, and 13, power line regions 60A, 60B, and 60C in which power lines are arranged are provided, and the interface circuit shown in FIG. Interface areas 30A, 30B, and 30C in which a plurality of 30 are arranged are provided.

  As described above, the interface regions 30A, 30B, and 30C are arranged outside the power supply line regions 60A, 60B, and 60C, and the elements constituting the interface circuits of the interface regions 30A, 30B, and 30C and the corresponding circuit blocks 11 , 12 and 13 are formed in well regions electrically isolated from each other on the chip surface. Therefore, the circuit block whose power supply is cut off can also cut off the supply of potential to the well region, thereby further reducing the power consumption.

  Each interface circuit provided in the interface regions 30A, 30B, and 30C blocks and stores signals output from the corresponding circuit blocks 11, 12, and 13, and is input from other circuit blocks. The signal to be transmitted is configured to pass as it is. In FIG. 5, the interface regions 30 </ b> A, 30 </ b> B, and 30 </ b> C are provided so as to surround the circuit blocks 11, 12, and 13, respectively, but are provided along some sides of the circuit blocks 11, 12, and 13. It may be done.

  In this embodiment, the power supply switches 23A, 23B, and 23C can cut off the supply of power to the circuit blocks 11, 12, and 13, respectively. However, the interface circuits and inter-block signals in the interface regions 30A, 30B, and 30C are used. The control circuit 40 is configured to be constantly supplied with power from the external power supply device 50. The inter-block signal control circuit 40 controls the interface circuit and the power switches 23A to 23C as in the first embodiment.

  According to this embodiment, since the power supply voltage of any circuit block can be arbitrarily interrupted in a state where the signal immediately before the power interruption is stored, it is possible to reduce power consumption while preventing malfunction of other circuit blocks. . It is also possible to configure the power supply of the two circuit blocks to be cut off.

  Next, an embodiment in which the present invention is applied to a microprocessor and an example of a cellular phone system using the microprocessor as a control device will be described with reference to FIG.

  In this embodiment, although not particularly limited, the center of the semiconductor chip 10 is a main power supply area 110, and the main power supply area 110 has a power supply in a standby mode of a chip such as a CPU (Central Processing Unit) or a cache memory. A circuit is provided to cut off the supply. A sub power source region 120 is provided around the main power source region 110. The sub power source region 120 has a circuit similar to the interface circuit 30 and a circuit similar to the inter-block signal control circuit 40 shown in FIG. In addition, an interrupt processing circuit 70 and a timer circuit 80 are provided as peripheral circuits of the CPU. These circuits are always supplied with power.

  In this embodiment, the interface circuit 30 among the circuits provided in the sub power supply area 120 is located on the innermost side (part from the center of the chip) of the sub power supply area 120 so as to surround the main power supply area 110 (CPU core portion). Has been placed. Although not particularly limited, a power supply line region 60A is provided between the main power supply region 110 and the sub power supply region 120, and a power supply line region is provided between the sub power supply region 120 and the I / O power supply region 130. 60B is provided, and the well regions on the substrate surfaces of the power supply regions 110 and 120 are electrically separated.

  Furthermore, in this embodiment, an I / O power supply region 130 is provided on the peripheral edge of the chip, which is outside the sub power supply region 120. The I / O power supply region 130 has a signal among pads that are external terminals of the chip. An input / output circuit connected to a pad used for input / output is provided. The semiconductor chip of this embodiment is provided with three power pads Pi, Ps, and Pm corresponding to the I / O power source region 130, the sub power source region 120, and the main power source region 110. Is supplied with a power supply voltage Vcc1 such as 3.3 V higher than the power supply voltage of the internal circuit from the I / O power supply pad Pi. This is because information can be exchanged with other devices outside the chip using a signal having a larger amplitude than that inside the chip. On the other hand, power supply voltages Vcc2 and Vcc3 such as 1.5 V are supplied to the sub power supply region 120 and the main power supply region 110, respectively. This is to reduce the power consumption of the internal circuit.

  In this embodiment, an internal status signal ISS is output from the CPU in the main power supply area 110 to the power supply device 50 outside the chip, and this internal status signal ISS indicates that the power supply can be cut off. In this case, the external power supply device 50 is configured to supply the standby signal SBY to the inter-block signal control circuit 40 to shut off the interface circuit and then shut off the power supply to the main power supply region 110.

  In addition, when a predetermined interrupt signal IRQ is input from the outside of the chip to the interrupt processing circuit 70 in the sub power supply area 120 in this power-off state, the interrupt processing circuit 70 returns the power to the inter-block signal control circuit 40. A request signal POQ is supplied. Then, the inter-block signal control circuit 40 outputs a standby release request signal SRQ to the external power supply device 50, and when the external power supply device 50 receives the standby release request signal SRQ, the power supply voltage is supplied to the main power supply region 110. Resume. Then, the CPU restarts the operation after the internal initialization. On the other hand, the inter-block signal control circuit 40 controls the conduction of the interface circuit 30 in anticipation of completion of the CPU initialization.

  Although not particularly limited, when the microprocessor of this embodiment is used in a mobile phone, the chip is connected to two buses BUS1 and BUS2. One bus BUS1 is connected to a liquid crystal display panel 210 and a RAM (Random Access Memory) 220 as a storage device. In addition, a baseband processing LSI 230 is connected to the other bus BUS 2, and a high frequency signal processing high frequency module 250 is connected between the baseband LSI 230 and the antenna 240.

  Further, in the microprocessor chip of this embodiment, while the supply of power to the CPU is cut off and the operation is stopped, the liquid crystal display panel is directly received by a signal from the baseband processing LSI 230 without going through the CPU. In order to be able to change the display of 210, a bypass line BPS for outputting an external signal input to a certain pad P1 as it is from the other pad P2 to the outside of the chip, a signal of the bypass line, and a signal from the CPU There is provided a selector SEL for performing switching. The selector SEL can be switched using a signal for the inter-block signal control circuit 40 to shut off the interface circuit 30.

  In FIG. 7, as an example of the inter-block signal of the present invention in the microprocessor of the above embodiment, the signal is output from the CPU core section of the main power supply area 110 to the outside of the chip via the input / output circuit of the I / O power supply area 130. Shows how to handle signals.

  As shown in FIG. 7, when the data signal DT1 and its output control signal DS1 are output from the CPU, the data signal DT1 and the output control signal DS1 pass through the signal gate means 31A and 31B of the interface circuit 30, respectively. Once stored in the storage means 32A, 32B. The input / output circuit of the I / O power supply region 130 is composed of, for example, an input / output buffer and a level conversion circuit, and the data signal DT1 is supplied from the storage means 32A to the level conversion circuit LS1 to be 0-1.5V or the like. The amplitude is converted to an amplitude such as 0-3.3V and supplied to the data input terminal of the output buffer BFF. On the other hand, the output control signal DS1 is supplied from the storage means 32B to the level conversion circuit LS2, converted from an amplitude such as 0-1.5V to an amplitude such as 0-3.3V, and supplied to the control terminal of the output buffer BFF. Is done.

  If the interface circuit 30 is not provided and the signal from the CPU is directly supplied to the level conversion circuits LS1 and LS2 and output, the output signal of the output buffer BFF is cut off by the power supply of the CPU being cut off. However, as shown in this embodiment, the interface circuit 30 is provided, and the storage unit 32A, 32B holds the previous signal state, so that the signal output to the outside of the chip is undefined. It is possible to prevent the malfunction of the other chips and thus the entire system.

  FIG. 8 shows a fourth embodiment of a semiconductor integrated circuit to which the present invention is applied.

  In this embodiment, when an internal circuit includes a circuit block 11 in which power is cut off in accordance with an operation mode and a circuit block 12 in which power is constantly supplied, the input / output circuit is set in accordance with each circuit block. Thus, the I / O unit 131 whose power is cut off is divided into the I / O unit 132 which is always supplied with power and operates. Between the circuit block 11 and the circuit block 12, an interface region 30A in which a plurality of interface circuits 30 as shown in FIG. 1 are arranged is provided.

  Further, among the signals output from the circuit block 11 whose power is shut off according to the operation mode, those which do not need to be output when the power is shut off are supplied to the I / O unit 131 where the power is shut off. Also, what is desired to be output is configured to be supplied via an interface region 30B in which a plurality of interface circuits 30 are arranged to the I / O unit 132 which is always supplied with power and operates.

  The inter-block signal control circuit 40 for controlling the interface circuit 30 in the interface regions 30A and 30B is provided in a part of the circuit block 12 to which power is always supplied. As a semiconductor integrated circuit having such a configuration, for example, a circuit in which the microprocessor and the baseband processing LSI 230 shown in FIG. 6 are integrated into one chip and the microprocessor is stopped can be considered.

  In this embodiment as well, the power supply to the circuit block 11 is cut off by the external power supply device 50. For this reason, the power supply control signal PCQ is output from the circuit block 12 to the external power supply device 50. However, as in the embodiment of FIG. It is also possible to configure.

  The invention made by the present inventor has been specifically described based on the embodiments. However, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the scope of the invention. Nor. For example, the storage means 32 in the interface circuit 30 in the above embodiment is configured so as to be able to form a scan path that operates as a shift register by chain coupling in series. The circuit block is operated after the test data is put in the LSI, and the output signal changed by the logic operation of the circuit block is stored in the storage means 32 in the interface circuit 30, and is again operated as a shift register and output to the outside of the chip. It is also possible to configure a test circuit to be configured.

  In the above description, the case where the invention made mainly by the present inventor is applied to the microprocessor which is the field of use behind the invention has been described. However, the present invention is not limited to this and the operation of some circuits is not limited thereto. It can be used for general semiconductor integrated circuits to be stopped.

DESCRIPTION OF SYMBOLS 10 Semiconductor chip 11, 12, 13 Circuit block 21 Power supply terminal 22 Power supply line 23 Power supply switch 30 Inter-block interface circuit 31 Signal gate means 32 Memory | storage means 33 Signal comparison circuit 40 Inter-block signal control circuit 50 External power supply 60A, 60B, 60C Power line area 110 Main power area 120 Sub power area 130 I / O power area

Claims (3)

A first circuit block in which the first power supply voltage is supplied in the first mode and the supply of the first power supply voltage is stopped in the second mode;
A second circuit block to which a second power supply voltage is supplied;
A third circuit block that is supplied with a third power supply voltage and outputs a first signal output from the first circuit block to the second circuit block;
The second circuit block includes an output buffer that outputs to the pad for outputting the first signal to the outside,
The third circuit block controls the first storage means for storing the state of the first signal and whether to supply or block the first signal from the first circuit block. First signal gating means,
The first signal gate means supplies the first signal in the first mode and stops supplying in the second mode;
The first storage means outputs the first signal held in the second mode to the output buffer . The third power supply voltage is equal to the first power supply voltage, and the second power supply voltage is higher than the first power supply voltage;
2. The semiconductor device according to claim 1, wherein the second circuit block includes a level conversion circuit that converts a signal of the third power supply voltage into a signal of the second power supply voltage . A second signal output from the first circuit block is input to the second circuit block via the third circuit block;
The third circuit block controls the second storage means for storing the state of the second signal and whether to supply or block the second signal from the first circuit block. Second signal gating means,
The second signal gating means supplies the second signal in the first mode and stops supplying in the second mode;
The said 2nd memory | storage means outputs the said 2nd signal hold | maintained in the said 2nd mode to the said output buffer, and controls whether the operation | movement of the said output buffer is effective or invalid. Semiconductor device.

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