JPH0556559A - Semiconductor device - Google Patents

Abstract

PURPOSE:To promote a low power consumption by stabilizing the operational characteristics, or the quality, of a digital signal processor DSP or the like in which a power source circuit POW is incorporated. CONSTITUTION:A power source circuit POW incorporated in a digital signal processor DSP or the like comprises a plurality of voltage generating circuits which form the inner power source voltages VCCI having different potentials on the basis of external power source voltages VCC, respectively, a power source controlling circuit which selectively forms a power source voltage selecting signal by monitoring the operational characteristics of a given logic gate, and a plurality of switching means to be selectively in on-state in accordance with the power source voltage selecting signal. Hence, the potential of the inner power source voltage is selectively switched in accordance with the operational characteristics, or the external conditions, of the logic gate and others constituting the inner circuit IC for the digital signal processor or the like.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device, and more particularly to a technique which is particularly effective when used in a digital signal processing device having a power supply circuit incorporated therein.

[0002]

2. Description of the Related Art There is a power supply circuit which forms a predetermined internal power supply voltage based on an external power supply voltage supplied from the outside and supplies the voltage to an internal circuit. There is also a semiconductor device such as a digital signal processing device that incorporates such a power supply circuit.

Regarding the power supply circuit, for example, Japanese Patent Laid-Open No. 57-57
-061981 and the like.

[0004]

In the conventional digital signal processing device and the like, the number of built-in power supply circuits is substantially one, and the potential fluctuation of the external power supply voltage and the temperature fluctuation around the device including the substrate are caused. Its main function is to form a stable internal power supply voltage that is not affected by the external conditions of and to supply it to the internal circuit.

However, the operating characteristics of the logic gates and the like which form the internal circuit change not only with the potential fluctuations of the power supply voltage but also with, for example, temperature fluctuations around the device. For this reason,
In a digital signal processing device or the like having a built-in power supply circuit as described above, changes in operating characteristics such as logic gates due to potential fluctuations in power supply voltage can be eliminated, but changes in operating characteristics due to temperature variations around the device can be eliminated. It is not possible. As a result, the operating characteristics of the digital signal processing device and the like change, and it is not possible to provide a stable quality digital signal processing device and the like.

On the other hand, the operating characteristics of logic gates and the like which compose internal circuits of digital signal processing devices and the like exhibit so-called process variation due to the manufacturing process, but the potential of the internal power supply voltage formed by the power supply circuit is as described above. It is set to a higher value with a margin after allowing for process variations. In other words, when viewed from a logic gate having good operating characteristics, the internal power supply voltage of high potential is received even though it can operate at a lower potential, which results in low consumption of digital signal processing devices. Electrification opportunities are compromised.

An object of the present invention is to provide a power supply circuit capable of switching the potential of the internal power supply voltage according to external conditions and operating characteristics of logic gates and the like which form an internal circuit.
Another object of the present invention is to stabilize the operating characteristics, that is, the quality of a digital signal processing device having a built-in power supply circuit, and to promote the reduction of power consumption thereof.

[0008]

The outline of the typical inventions among the inventions disclosed in the present application will be briefly described as follows. That is, a power supply circuit built in a digital signal processing device or the like is monitored by monitoring a plurality of voltage generation circuits that respectively form internal power supply voltages having different potentials based on an external power supply voltage and operating characteristics of predetermined logic gates. A power supply control circuit that selectively forms a power supply voltage selection signal and an internal power supply voltage that is selectively turned on according to the power supply voltage selection signal and that is output from the corresponding voltage generation circuit is selectively transmitted to the internal circuit. It is composed of a plurality of switch means.

[0009]

According to the above means, the potential of the internal power supply voltage can be selectively switched according to the operating characteristics of the logic gate or the like forming the internal circuit of the digital signal processing device or the like, that is, the external condition. It is possible to stabilize the operating characteristics of the processing device or the like, that is, the quality thereof, and set the potential of the internal power supply voltage to a low value in accordance with the performance thereof to promote the low power consumption of the digital signal processing device or the like.

[0010]

1 is a block diagram of an embodiment of a digital signal processor DSP to which the present invention is applied. 2 shows a power supply control circuit VCT included in the power supply circuit POW of the digital signal processing device DSP shown in FIG.
A block diagram of one embodiment of L is shown. Based on these drawings, the outline of the configuration and operation of the digital signal processing device and the power supply circuit of this embodiment and the features thereof will be described. The circuit elements forming each block of FIGS. 1 and 2 are formed on a single semiconductor substrate such as single crystal silicon by a known integrated circuit manufacturing technique.

In FIG. 1, a digital signal processing device DSP of this embodiment has a predetermined internal power supply based on an internal circuit IC formed by combining a large number of logic gates and the like and an external power supply voltage VCC supplied from the outside. And a power supply circuit POW that forms a voltage VCCI and supplies it to the internal circuit IC. Here, the external power supply voltage VCC is a positive power supply voltage such as + 5V, although not particularly limited. Further, the ground potential VSS supplied from the outside together with the external power supply voltage VCC becomes the reference potential of the circuit as it is. The following description will be focused on the power supply circuit POW, and the description of the internal circuit IC not directly related to the invention will be omitted.

The power supply circuit POW is not particularly limited,
External power supply voltage supply point VCC and internal power supply voltage supply point VCC
It is provided with three sets of voltage generating circuits and switch means provided in parallel with I. That is, the external power supply voltage supply point VCC has a first voltage generating circuit composed of two diodes D1 and D2 arranged in series and a switching means S1.
Is connected to the internal power supply voltage supply point VCC1 via the second voltage generating circuit composed of one diode D3 and the switch means S2, and is further connected to the internal power supply voltage supply point VCCI. Is connected to the internal power supply voltage supply point VCCI via the third voltage generating circuit having no diode, that is, the constituent element, and the switch means S3. Here, each of the diodes D1 to D3 is composed of, for example, a bipolar transistor formed with a relatively large size, and its base-emitter voltage VBE.
Has a forward voltage equivalent to. Also, the switch means S1
~ S3 is an MO formed with a relatively large size
It is composed of an SFET (insulated gate type field effect transistor) and is selectively turned on in accordance with power supply voltage selection signals VS1 to VS3 supplied from the power supply control circuit VCTL.

When the power supply voltage control signal VS1 is at a high level, in the power supply circuit POW, the switch means S1 is turned on, and the first voltage generating circuit becomes effective. Therefore, the external power supply voltage VCC is equal to that of the two diodes D1.
, And the forward voltage of D2, that is, 2VBE, are supplied to the internal circuit IC as the internal power supply voltage VCCI. On the other hand, when the power supply voltage control signal VS2 is at the high level, in the power supply circuit POW, the switch means S2 is turned on, and the second voltage generation circuit becomes effective. Therefore, the external power supply voltage VCC is equal to one diode D
After being reduced by the forward voltage of 3, that is, VBE, it is supplied to the internal circuit IC as the internal power supply voltage VCCI.
Similarly, when the power supply voltage control signal VS3 is at the high level, in the power supply circuit POW, the switch means S3 is turned on, and the third voltage generation circuit becomes effective. Therefore, the external power supply voltage VCC becomes the internal power supply voltage VCCI without being lowered and is supplied to the internal circuit IC. The internal power supply voltage VCCI is the power supply control circuit VCTL.
Will also be supplied.

As shown in FIG. 2, power supply control circuit VCTL includes a ring oscillator ROSC which uses the internal power supply voltage VCCI as an operating power supply. In this example,
The ring oscillator ROSC is composed of a plurality of logic gates having the same operation characteristics as the logic gates forming the internal circuit IC, and forms the clock signal CP having a predetermined center frequency. As is well known, the operating characteristic including the propagation delay time of a logic gate is the operating power supply, that is, the internal power supply voltage V.
The clock signal C output from the ring oscillator ROSC changes with changes in external conditions such as the potential of the CCI and the temperature around the device on the semiconductor substrate surface.
The frequency of P also changes.

The clock signal CP is a frequency counter FC
Supplied to TR. The frequency counter FCTR is further supplied with the reset signal RST from the reset control circuit RSTC, and its output signal, that is, the internal control signals VU and VD are supplied to the power supply selection circuit VSEL.

Although not particularly limited, the reset control circuit RSTC includes a crystal oscillator with high oscillation accuracy, forms a reset signal RST having a stable cycle, and supplies the reset signal RST to the frequency counter FCTR. The frequency counter FCTR is periodically reset by the reset signal RST, and constantly counts the number of pulses of the clock signal CP, that is, its frequency during that period. And the clock signal CP
If the frequency does not reach a predetermined value, in other words, if the ring oscillator ROSC, that is, the logic gate forming the internal circuit IC has a relatively long transmission delay time and a relatively slow operation speed, one of the internal control signals VU When the frequency of the clock signal CP exceeds a predetermined value, in other words, when the transmission delay time of the logic gate is relatively short and its operating speed is relatively fast, the other internal control signal VD is set to high. Level. When the frequency of the clock signal CP is within a predetermined range, both the internal control signals VD and VU are at low level.

Next, the power source selection circuit VSEL has an internal control signal VU and VU supplied from the frequency counter FCTR.
According to D, the power supply voltage selection signals VS1 to VS3 are alternatively set to the high level. That is, the power supply selection circuit VS
EL is, when the internal control signal VU is at a high level,
The power supply voltage selection signal that should be high level is changed from VS1 to VS
2 or VS2 to VS3 sequentially, and conversely, when the internal control signal VD is set to the high level, the power supply voltage selection signal to be set to the high level is sequentially shifted from VS3 to VS2 or VS2 to VS1. When the internal control signals VU and VD are both set to low level, the power supply voltage selection signal V which is set to high level at that time
S1 to VS3 are continuously set to the high level.

As described above, the potential of the internal power supply voltage VCCI is lower than the external power supply voltage VCC by 2VBE when the power supply voltage selection signal VS1 is at the high level, and the power supply voltage selection signal VS2 is at the high level. At this time, the external power supply voltage VCC is lowered by VBE. When the power supply voltage selection signal VS3 is at the high level, the potential of the internal power supply voltage VCCI is set to the same potential as the external power supply voltage VCC. As a result, the potential of the internal power supply voltage VCCI is the frequency of the power supply voltage selection signals VS1 to VS3, that is, the clock signal CP, in other words, the power supply control circuit VC.
TL ring oscillator ROSC, that is, internal circuit IC
Are selectively switched according to the operating characteristics of the logic gates constituting the. However, the internal power supply voltage VCC
The potential of I depends on external conditions such as the potential of the external power supply voltage VCC and the ambient temperature of the device on the semiconductor substrate, as well as the internal circuit IC.
Is selectively switched and optimized in accordance with the process variation of the logic gates that make up the logic gates, and is set to a lower value according to the performance of the logic gates. As a result, the operating characteristics, that is, the quality, of the digital signal processing device DSP is stabilized, and the reduction of power consumption thereof is promoted.

As shown in the above embodiment, the present invention is applied to a digital signal processor DSP having a built-in power supply circuit.
The following operational effects can be obtained by applying the invention to a semiconductor device such as. That is, (1) a power supply circuit incorporated in a digital signal processing device or the like is provided with a plurality of voltage generating circuits each forming an internal power supply voltage having a different potential based on an external power supply voltage, and operating characteristics of a predetermined logic gate. A power supply control circuit that monitors and selectively forms a power supply voltage selection signal, and an internal power supply voltage that is selectively turned on according to the power supply voltage selection signal and that is output from the corresponding voltage generation circuit. And a plurality of switch means for transmitting the signal to the internal power supply voltage. The effect that can be obtained is obtained. (2) According to the above item (1), it is possible to stabilize the operating characteristics of the internal circuit included in the digital signal processing apparatus and the like, to stabilize the operating characteristics of the digital signal processing apparatus and the like, and to stabilize the quality thereof. The effect is obtained. (3) According to the above item (1), the potential of the internal power supply voltage can be set to a low value in accordance with the operating characteristics of the internal circuit, so that the power consumption of the digital signal processing device or the like can be promoted. ..

Although the invention made by the present inventor has been specifically described based on the embodiments, the invention is not limited to the above embodiments, and various modifications can be made without departing from the scope of the invention. Needless to say. For example, in FIG. 1, the number of voltage generating circuits provided in the power supply circuit POW is arbitrary, and the number of diodes forming each voltage generating circuit is also arbitrary. Also, the power circuit POW
Is an internal power supply voltage VCC by means other than a diode.
The potential of I may be changed or may be changed linearly. Switch means S1 to S3
May use a switch means other than the MOSFET, and its control method is also arbitrary. The power supply control circuit VCTL of the power supply circuit POW can identify the operating characteristics of the logic gate by using means other than monitoring the frequency of the ring oscillator ROSC, and various selection methods of the internal power supply voltage depending on the identification result. Examples of can be considered.
Further, the digital signal processor DSP and the power supply circuit P
Various embodiments can be adopted such as the block structure of the OW and the polarity and absolute value of the power supply voltage.

In the above description, the case where the invention made by the present inventor is mainly applied to the digital signal processing device and its power supply circuit, which are the fields of application in the background, has been described, but the invention is not limited thereto. For example, the invention can be applied to a gate array integrated circuit device including a power supply circuit and various memory integrated circuit devices. The present invention can be widely applied to semiconductor devices having at least a power supply circuit.

[0022]

The power supply circuit incorporated in a digital signal processor or the like has a plurality of voltage generating circuits for forming internal power supply voltages having different potentials based on an external power supply voltage, and operating characteristics of a predetermined logic gate. A power supply control circuit that monitors and selectively forms a power supply voltage selection signal and an internal power supply voltage that is selectively turned on according to the power supply voltage selection signal and that is output from the corresponding voltage generation circuit is selectively transmitted to the internal circuit. By configuring it with a plurality of switch means, it is possible to selectively switch the potential of the internal power supply voltage according to the operating characteristics of the logic gates and the like that form the internal circuit, that is, the external conditions, so that the digital signal processing device, etc. The operating characteristics of the power supply can be stabilized and its quality can be stabilized, and the potential of the internal power supply voltage can be set to a low value in accordance with the operating characteristics of the internal circuit. It is possible to promote the low power consumption of such apparatus.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a digital signal processing device to which the present invention is applied.

FIG. 2 is a block diagram showing an embodiment of a power supply control circuit included in the power supply circuit of the digital signal processing device of FIG.

[Explanation of symbols]

DSP ... Digital signal processing device, IC ... Internal circuit, POW ... Power supply circuit, VCTL ... Power supply control circuit, D1 to D3 ... Diode, S1 to S3 ...
Switch means. ROSC ... Ring oscillator, FC
TR ... Frequency counter, RSTC ... Reset control circuit, VSEL ... Power supply selection circuit.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Office reference number FI technical display location H03K 17/30 J 9184-5J 19/00 A 6959-5J

Claims (3)

[Claims] 1. A power supply circuit for forming a predetermined internal power supply voltage based on the external power supply voltage and selectively switching the potential of the internal power supply voltage according to a predetermined external condition or the like. Semiconductor device. 2. The power supply circuit selectively monitors the operating characteristics of a plurality of voltage generation circuits that form internal power supply voltages having different potentials based on an external power supply voltage and a predetermined logic gate to selectively supply the power supply voltage. A power supply control circuit for forming a selection signal; and a plurality of switch means for selectively transmitting an internal power supply voltage output from the corresponding voltage generation circuit selectively turned on in accordance with the power supply voltage selection signal to the internal circuit. The semiconductor device according to claim 1, further comprising: 3. The semiconductor device is a digital signal processing device, wherein each of the voltage generating circuits includes a predetermined number of diodes for shifting a potential of an external power supply voltage to a corresponding internal power supply voltage. The semiconductor device according to claim 1, wherein the semiconductor device is a semiconductor device.