JPH04171977A - Substrate potential generation circuit - Google Patents

Abstract

PURPOSE:To obtain a substrate potential generation circuit by means of which an oscillation frequency is oscillated stably and which has reduced a current consumption by providing the following: an oscillation circuit which can be changed over to a plurality of different oscillation frequencies; waveform-reshaping circuits installed at individual oscillation frequencies; and a charge pumping circuit which uses the output of the waveform-reshaping circuits as an input. CONSTITUTION:When a signal phi1 is at a high potential, an oscillation circuit 1 takes a higher oscillation frequency and a waveform-reshaping circuit 2 becomes inactive. As a result, sinusoidal waves as an output waveform of the oscillation circuit 1 are waveform-reshaped by a waveform-reshaping circuit 4 and are input to a charge-pumping circuit 3. When the signal phi1 is at a low potential, the oscillation circuit 1 takes a lower oscillation frequency and the waveform-reshaping circuit 4 becomes inactive. As a result, sinusoidal waves as the output waveform of the oscillation circuit 1 are waveform-reshaped by the waveform- reshaping circuit 2. At this time, since the waveform-reshaping circuit 2 is not required to operate with reference to the higher frequency and can be designed optimally with reference to the lower frequency, a current consumption can be reduced as compared with that of the waveform-reshaping circuit 2. The output of the charge-reshaping circuit 2 is input to the charge pumping circuit 3 in the same manner as a case where the potential of the signal phi1 is high.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a substrate potential generation circuit, and more particularly to a substrate potential generation circuit whose current capability can be switched.

[Conventional technology]

A conventional substrate potential generation circuit of this type is a MOS dynamic random access memory (hereinafter referred to as MO8DRAM).
), but this MO8D
With the decline in the unit price of RAM and the expansion of the fields of use, there has been a demand for lower current consumption.

An example of a conventional circuit will be shown and explained below.

FIG. 2 is a circuit diagram showing an example of a substrate potential generation circuit integrated on the same semiconductor substrate as a conventional MO8DRAM.

In FIG. 2, the substrate potential generation circuit includes an oscillation circuit 1, a waveform shaping circuit 2, and a charge pump circuit 3.

Here, the oscillation circuit 1 includes P-channel transistors Q1 to
Q9. Q15 and N-channel transistors Q16 to Q
25. The waveform shaping circuit 2 includes P-channel transistors QIO and Qll.

Q12 and N-channel transistor Q26. Q27゜Q
28. Charge pump circuit 3 includes P-channel transistors Q13. Q14, N-channel transistors Q29 to Q31, and a capacitor C1.

In FIG. 2, an oscillation circuit 1 composed of three stages of CMOS inverters is configured to oscillate at a high frequency when the signal φ1 is at a high potential, and to oscillate at a low frequency when the signal φ1 is at a low potential. .

A waveform shaping circuit 2 configured with a CMOS inverter has a function of converting a sine wave output from the oscillation circuit 1 into a square wave.

The charge pump circuit 3 has a function of receiving the square wave obtained by the waveform shaping circuit 2 as input and generating a potential below the ground potential.

In FIG. 2, the signal φ1 is controlled by the MO8DRAM integrated on the same substrate, and when it is necessary to rapidly lower the substrate potential or when a large amount of substrate current flows, the signal φ1 becomes a high potential. , the oscillation frequency of the oscillation circuit I becomes faster, and the ability to pump out charges from the substrate increases, but current consumption also increases accordingly.

On the other hand, when the MO8DRAM is in an inactive state and the substrate potential is at a necessary and sufficient potential, the signal φ1 becomes a low potential, the oscillation frequency of the oscillation circuit 1 becomes low, and the ability to extract charges from the substrate decreases. , current consumption is also reduced.

=Problem to be Solved by the Invention] As explained above, in the conventional substrate potential generation circuit, the ability to pump out charges from the substrate changes depending on the operating state of the MO8DRAM integrated on the same substrate, and Since the current consumption changes accordingly, there is an effect of reducing unnecessary current consumption, but the waveform shaping circuit 2 shown in FIG. 2 cannot be designed to be optimal for a plurality of different frequencies. Therefore, there is a problem in that unnecessary current consumption flows particularly when the oscillation circuit 1 has a low oscillation frequency. This is because a sine wave is applied as an input to the CMOS inverter that constitutes the waveform shaping circuit 2, so a through current flows from the power supply potential to the ground potential.
Although it is possible to reduce the through current by reducing the capacity of the S inverter, this causes the problem that it does not operate at high oscillation frequencies.

SUMMARY OF THE INVENTION An object of the present invention is to provide a substrate potential generation circuit that solves the above-mentioned drawbacks, has a stable oscillation frequency, and reduces current consumption.

[Means to solve the problem]

The structure of the substrate potential generation circuit of the present invention is characterized by comprising an oscillation circuit that can be switched to a plurality of oscillation frequencies, a waveform shaping circuit provided for each of the oscillation frequencies, and a charge pump circuit.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a circuit diagram showing a substrate potential generation circuit according to an embodiment of the present invention.

In FIG. 1, this embodiment includes an oscillation circuit 1, waveform shaping circuits 2 and 4, and a charge pump circuit 3.

Here, the oscillation circuit 2 includes a P-channel transistor Q1
~QIO and N-channel transistors Q24 to Q33
and has.

The waveform shaping circuit 2 includes P-channel transistors Qll~
Q16, and N-channel transistors Q34 to Q39.

The waveform shaping circuit 4 below it includes P-channel transistors Q17 to Q20 and N-channel transistors Q40 to Q20.
Q43.

The charge pump circuit 3 includes a P-channel transistor Q
21 to Q23 and N-channel transistors Q44 to Q
47.

The oscillation circuit 1 is similar to the oscillation circuit shown in FIG.
This is an oscillation circuit that has a high oscillation frequency when the signal φ1 is at a high potential, and a low oscillation frequency when the signal φ1 is at a low potential.

The waveform shaping circuit 2 is activated when the signal φ1 is at a low potential,
It is inactivated when the signal φ1 is at a high potential, and is designed to reduce current consumption for waveform shaping of the lower oscillation frequency of the oscillation circuit 1.

The charge pump circuit 3 is a charge pump circuit similar to that shown in FIG.

The waveform shaping circuit 4 is activated when the signal φ1 is at a high potential,
It is inactivated when the potential is low, and is designed to reduce current consumption for waveform shaping of the higher oscillation frequency of the oscillation circuit 1.

Next, the operation shown in FIG. 1 will be explained. When the signal φ1 is at a high potential, the oscillation circuit l takes on a higher oscillation frequency and the waveform shaping circuit 2 becomes inactive, so the sine wave that is the output waveform of the oscillation circuit l is shaped by the waveform shaping circuit 4. and is input to the charge pump circuit 3.

When the signal φ1 is at a low potential, the oscillation circuit 1 takes on the lower oscillation frequency and the waveform shaping circuit 4 becomes inactive, so the sine wave that is the output waveform of the oscillation circuit 1 is shaped by the waveform shaping circuit 2. be done.

At this time, the waveform shaping circuit 2 is better than the waveform shaping circuit 2 shown in FIG. 1 because it does not need to operate for higher frequencies and can be optimally designed for lower frequencies. It becomes possible to reduce current consumption.

The output of the waveform shaping circuit 2 is input to the charge pump circuit 3 in the same way as when the signal φ1 is at a high potential.

〔Effect of the invention〕

As explained above, the substrate potential generation circuit according to the present invention has a dedicated waveform shaping circuit for each of a plurality of different oscillation frequencies. This makes it possible to reduce the current consumption to the necessary minimum, which has the effect of reducing current consumption.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram of a substrate potential generation circuit according to an embodiment of the present invention, and FIG. 2 is a circuit diagram of a conventional substrate potential generation circuit. 1... Oscillation circuit, 2, 4... Waveform shaping circuit, 3... Charge pump circuit, C1...
... Contensa. Agent Patent Attorney Oto Uchihara

Claims (1)

[Claims] A substrate potential characterized by comprising an oscillation circuit that can be switched to a plurality of different oscillation frequencies, a waveform shaping circuit provided for each of the oscillation frequencies, and a charge pump circuit whose input is the output of these waveform shaping circuits. generation circuit.