JPS63224665A - Generating circuit for substrate voltage - Google Patents

Abstract

PURPOSE:To compensate for the fluctuation of substrate voltage by operating all charging pump circuits when substrate voltage is higher than a set value and stopping the operation of partial charging pump circuits when substrate voltage is lower than it. CONSTITUTION:Two of charging pump circuits 3a, 3b are mounted, and a substrate-voltage VBB level detector 6 is constituted of FETQ5-Q8 in a P channel MOSFETQ5 and N channel MOSFETQ6-Q8. A substrate-voltage generating circuit is organized of an oscillator 1, the charging pump circuits 3a, 3b, inverters 4a, 4b, an AND circuit 5 and said detector 6. Accordingly, an output detecting substrate voltage VBB and an output from an oscillator 1c are input to the pre-stage of the charging pump circuits 3b through the AND circuit 5, and the charging pump circuits 3b are stopped when substrate voltage VBB is lower than -3V, thus reducing power consumption.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a substrate voltage generation circuit that generates a substrate voltage of a semiconductor device.

[Conventional technology]

FIG. 2 shows the basic circuit of the substrate voltage generation circuit. In the figure, 1 is a ring oscillator, 2 is a driver, and the ring oscillator 1 is constructed by, for example, inverters connected in series. Further, C0 is a capacitor, Q, , Q are N-channel MOS F constituting the charge pump circuit 3.
It is ET. Also, V is this N channel k M OS F
The node connecting E T Q r and Qt, ■□ is the output terminal of the substrate voltage generation circuit.

FIG. 3 schematically shows the voltage waveforms of φOr v, , Vlm shown in FIG. 2. In the figure, φ. is a charge pump circuit drive signal, which is output from the driver 2 and whose oscillation period is determined by the ring oscillator 1.

Next, the operation will be explained. When the voltage of the drive signal φ0 changes from O to vl-, the node ■. The voltage of capacitor C0
rises from O to V due to capacitive coupling by. However, at this time, the transistor Q2 is turned on, and therefore, if the threshold voltage of the transistor Q2 is V THE, then the node ■. The voltage of decreases to ■ and □. Then the drive signal φ. When V drops from V to O, the voltage at node v0 increases to the above v7H due to capacitive coupling by capacitor C0.
2 to VTH2v. At this time transistor Q2
is in the OFF state, but since the transistor Q is in the ON state, the substrate voltages .

By repeating the above operation and assuming that the threshold voltage of transistor Q1 is VTMI, the substrate voltage becomes ■.

eventually becomes ■A□ +Vrxt V, and becomes stable. However, in reality, the substrate voltage fluctuates under the influence of the operations of various circuits configured on the semiconductor chip.

For example, a circuit as shown in FIG. 4 has been proposed as a substrate voltage generating circuit that quickly compensates for such fluctuations. In the figure, 1 is a ring oscillator, la, lb, l
c and ld are inverters constituting the 3-ring oscillator 1. Also 4a.

4b is an inverter that inverts the output of the ring oscillator 1 and outputs it to the charge pump circuits 3a and 3b;
s*Q3> is a P-channel MOS FET.

Q,,,Q,b,Q,□ Qzb,Q4□ Q4b is N
Channel MO3FET. Further, co,,co, are capacitors.

The inverter 4 consisting of the MOSFET Q3 and Qa corresponds to the driver in FIG.

This substrate voltage generation circuit is an example including two charge pump circuits, and in the figure, two charge pump circuit drive signals φ1. φ2 is approximately 180″ out of phase.

FIG. 5 schematically shows waveforms illustrating the operation of this circuit.

The operation of each charge pump circuit 3a, 3b is the same as in the case of FIG. 2, and the substrate voltage V□ ultimately becomes VTMI +VrHt VP as in the case of FIG.
Since the driving signals φ and φ2 are out of phase by 180'', it takes only a short time for the substrate voltage Vll to reach the stable potential of VTHL +vtoz-V. Therefore,
■ Board voltage due to influence of other circuits.

fluctuates, Vllll becomes VTMI +Vt)lz Vp
If it becomes higher, this substrate voltage generation circuit can quickly compensate for the variation.

[Problem that the invention seeks to solve]

However, the substrate voltage V1m becomes Vy due to the influence of other circuits.
l+ +Va. -■, if it becomes lower, the charge pump circuit will no longer contribute to Vo, and the circuit in Figure 4 above has two charge pump circuits, so there are also two drivers, and only one charge pump circuit. There is a problem in that the driver consumes more power than a substrate voltage generation circuit which is not equipped with the driver, resulting in wasted power consumption.

This invention was made to improve the above-mentioned problems, and an object of the present invention is to provide a substrate voltage generation circuit that can quickly compensate for fluctuations in substrate voltage and further reduce power consumption. .

[Means for solving problems]

In the substrate voltage generation circuit according to the present invention, when the substrate voltage is higher than a set value, all the charge pump circuits, which are provided in plurality for one ring oscillator and whose drive signals are all different in phase, are operated, and the substrate voltage is increased. The charge pump circuit is provided with an operation control means that stops the operation of a part of the charge pump circuit when the charge pump circuit is lower than a set value.

[Effect]

In this invention, all the charge pump circuits are operated when the substrate voltage is higher than the set value, and some of the charge pump circuits are stopped when the substrate voltage is lower than the set value. Not only can fluctuations in substrate voltage be quickly compensated for, but also power consumption can be reduced.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram showing a substrate voltage generator circuit according to an embodiment of the present invention, and shows an example including two charge pump circuits. In the figure, the same symbols as in FIG. 4 indicate the same parts, Q,
is a P-channel MO3FET.

Qb , Q7 , Qe are N-channel MOS FETs, and 6 is these MO3FETs Qs , 'Qa , Q
? .

This is a v0 level detection circuit 6 composed of Q. 5
is a two-man power AND circuit in which the output of this vIIll level detection circuit is connected to one input of the first and second inverters 7.82, and the other input is connected to the inverter IC of ring oscillator 1. The output of the inverter 4b is connected to the inverter 4b.

The basic idea of the substrate voltage generation circuit according to this embodiment is as follows.
The idea is to reduce power consumption by disabling some of the plurality of charge pump circuits when the substrate voltage becomes lower than necessary.

Next, the operation will be explained.

In FIG. 1, charge pump drive signal φ.

is always oscillated regardless of the value of the substrate voltage ■□, but the charge pump drive signal φ2 may or may not oscillate depending on the value of V-. That is, if the threshold voltages of N-channel transistors Qs, Qb, Q7, and Q are set to ■7, the gate of transistor Q is grounded, so when VBm≦−3vyO, Qb, Q
? , Qs are in the ON state 9L, the output of the v0 level detection circuit goes to the "L" level, and one input of the AND circuit 5 goes to the "L" level, so the drive signal φ2 is fixed at the "H" level. On the other hand, when Va++> 3Va, 1. ,(
Since it is impossible for all three 1,,Q, to be in the ON state, ■
.

The output of the level detection circuit becomes °H'' level, and the drive signal φO oscillates. Therefore, if ■72 lv, ■□<-
When the voltage is 3V, only the charge pump circuit 3a driven by the drive signal φ1 operates, and therefore the power consumption can be lower than that of the conventional circuit.

As described above, according to this embodiment, when the substrate voltage V0≦-3V, the L" level is output, and when V sit > 3 V, the "H" level is output. A V□ level detection circuit is provided,
Furthermore, since an AND circuit that ANDs the output of this circuit and the output of the ring oscillator IC is provided before the second charge pump circuit, when the substrate voltage V□ is lower than -3V, the second charge pump circuit is activated. can be stopped to reduce power consumption, and when Vlm is greater than 13
．． By activating the second charge pump circuit, VBm can be quickly brought to a desired value.

Note that although the above embodiment shows a case where two charge pump circuits are provided, three or more charge pump circuits may be provided. Further, the value of the capacitor C0 does not need to be exactly the same in each charge pump circuit. Also transistor Q
It is not necessary that the threshold voltage of transistor Qt -VT) and the threshold voltage of transistor Qt take exactly the same value in each charge pump circuit. Also, the VBB mentioned in this example
The level detection circuit is only an example of a level detection circuit, and other circuit configurations may be used.

〔Effect of the invention〕

As described above, according to the substrate voltage generation circuit according to the present invention, all the charge pump circuits are operated when the value of the substrate voltage V□ is equal to or higher than the set value, and when the value of the substrate voltage v0 is equal to or lower than the set value. In this case, since an operation control means for stopping the operation of a part of the charge pump circuit is provided, power consumption can be reduced and the substrate voltage VlB can be quickly brought to a desired value.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a substrate voltage generation circuit according to an embodiment of the present invention, FIG. 2 is a diagram showing a basic circuit of the substrate voltage generation circuit,
FIG. 3 is a schematic diagram of waveforms showing the operation of the substrate voltage generation circuit shown in FIG. 2, FIG. 4 is a diagram showing an example of a substrate voltage generation circuit that quickly compensates for fluctuations in V FIG. 2 is a schematic diagram of waveforms showing the circuit operation. In the figure, 1 is a ring oscillator (oscillator), 1a~
1d is an inverter, 3a and 3b are charge pump circuits,
4a and 4b are inverters (drivers), 5 is an AND circuit, and 6 is a v□ level detection circuit. Note that the same reference numerals in the figures indicate the same or equivalent parts. Fig. 1 1: Tanog 7 simulator 1o~1d:/n//-Y3G, 3b: fp-shi1°〃βυγ 5: AND#5 4a, 4b: Dan/l-Y6: vss 1/'$ lI$Δ775 Figure 2 Part 3 ■BB---, Eeyoe, -〇

Claims (2)

[Claims] (1) In a circuit that generates a voltage to be applied to a substrate of a semiconductor device, one oscillator generates periodic pulses, and each of the circuits is driven by pulses having different phases that are transmitted from the oscillator via a driver, A plurality of charge pump circuits that supply the output voltage to the board, and when the board voltage is higher than the set value, all the charge pump circuits are operated, and when the board voltage is lower than the set value, some of the charge pump circuits are operated. and operation control means for operating only the charge pump circuit. (2) Two charge pump circuits are provided, and the pulses driving each charge pump circuit have a phase of approximately 1.
The substrate voltage generating circuit according to claim 1, wherein the substrate voltage generating circuits are different by 80 degrees.