JP2693494B2 - Power conversion circuit - Google Patents

Description

The present invention relates to a power supply conversion circuit for operating an internal circuit such as an LSI with a voltage lower than that of an external power supply, and more particularly, to one of the potentials of the external power supply. The present invention relates to a power conversion circuit for level conversion.

[Prior Art] FIG. 9 shows a conventional power supply conversion circuit for raising a low potential level of an external power supply (hereinafter simply referred to as an external low power supply) in order to obtain an internal power supply of an LSI internal circuit. External low power supply in the figure
V _EE is -5.2V, which indicates a power supply conversion circuit that raises this to -3V as the low potential level V _SS of the internal power supply of the LSI internal circuit. Figure 9 shows external high power supply (high potential level of external power supply)
Conventional power supply conversion circuit that lowers (for example, IEEE JOURN
AL OF SOLID-STATE CIRCUITS, pp657-662, VOL.SC-22,
There is NO.5 Oct., 1987. ) Is applied to the power conversion of the external low power supply, and the potential fluctuation detection circuit 1 and the limiter circuit 2 are connected to the low potential level V _SS side of the internal circuit 3. The potential fluctuation detection circuit 1 is composed of a bipolar differential amplifier circuit, and feeds back the power supply voltage V _SS of the internal circuit 3 based on the reference voltage V _REF2 (−3V) to match V _SS with V _REF2. A constant voltage is generated. The limiter circuit 2 is
It is composed of a bipolar transistor Q ₁ and clamps the internal power supply V _SS to −3.0V by applying a reference voltage V _REF1 (−2.2V) to the base.

The circuit shown in FIG. 9 can be a circuit for obtaining an internal power source by lowering the high potential side of the external power source by changing the connection or the polarity of the transistor.

However, such conversion to the internal power supply has the following problems, especially in the case of a large current, and has been a problem that needs to be solved.

[Problems to be Solved by the Invention] When a large current flows in the internal circuit 3 of the above circuit, the bipolar differential amplifier circuit has a configuration in which the same current as the internal circuit 3 flows in the differential transistor pair. Power consumption increases.

(Ii) The occupied area of each element increases.

However, it is not practical as a power conversion circuit that can handle a large current.

SUMMARY OF THE INVENTION It is an object of the present invention to solve this problem and provide a power supply conversion circuit for an LSI internal power supply, which converts the level of one potential of an external power supply, consumes less power, occupies less area, and has less voltage fluctuation. .

[Means for Solving the Problems] In order to achieve the above object, the present invention has taken the following measures.

1. A constant current source composed of a current mirror circuit is connected in series to an internal circuit such as an LSI, an external power supply voltage is applied to the series circuit, and a clamp circuit is provided in parallel with the internal circuit.

2. In the configuration described in paragraph 1, further, a comparison voltage input corresponding to the reference voltage input of the differential amplifier circuit is connected to the connection point between the internal circuit and the constant current source, and the output of the differential amplifier circuit is used. A circuit for controlling the transistor connected in parallel to the current source of the current mirror circuit that constitutes the constant current source is provided.

The first term corresponds to FIG. 1 and the second term corresponds to FIG.

[Operation] The current mirror circuit connects, for example, the bases of input and output transistors connected to the same power supply, and the base and collector of the input transistor are connected to each other. This makes it possible to control the current of the transistor to a predetermined current. At that time, if the emitter area of the output transistor is larger than that of the input transistor, a large output current can be obtained with a small input current, and a large output current can be controlled with a constant current by keeping the small input current constant. It becomes possible to do.

For a constant current source composed of such a current mirror circuit
If an internal circuit such as an LSI is connected, the output constant current of the current mirror circuit is set so that the input voltage becomes a predetermined voltage when the internal circuit has low impedance, and a clamp circuit is provided in parallel with the internal circuit Even if the input impedance of the circuit changes so as to increase, the input voltage becomes constant.

At that time, if the constant current source is connected in series to the low potential side of the internal circuit and an external power supply is applied to this series circuit, the low potential side level of the external power supply is raised and a predetermined voltage is applied to the internal circuit. By connecting a constant current source in series to the high potential side of the internal circuit, it is possible to lower the high potential side level of the external power supply and apply a predetermined voltage to the internal circuit.

That is, a constant current source composed of a current mirror circuit is connected in series to an internal circuit, an external power supply voltage is applied to the series circuit, and a clamp circuit is provided in parallel with the internal circuit. Not only is it possible to use a power supply conversion circuit that converts the level of electric potential, but because a large load current can be controlled with a small current in the conversion circuit, it is possible to reduce the power consumption and occupied area of the power supply conversion circuit and reduce voltage fluctuations. to enable.

Further, to such a power conversion circuit, a comparison voltage input corresponding to the reference voltage input of the differential amplifier circuit is connected to the connection point between the internal circuit and the constant current source, and by the output of the differential amplifier circuit,
The additional circuit provided with the circuit for controlling the transistor connected in parallel to the current source of the current mirror circuit constituting the constant current source has, for example, an input impedance of the internal circuit smaller than the impedance that can be obtained by the input voltage and the input set current. In such a case, the change in the input voltage is amplified by comparison with the reference voltage, and as a result, the constant current value is increased. As a result, the power supply voltage of the internal circuit is kept constant.

Therefore, this additional circuit makes it possible to make the constant current value of the input variable, and also makes it possible to reduce the constant current source current, which has the advantage of further reducing power consumption.

[Embodiment] FIG. 1 shows an embodiment of the present invention in which V is connected to the ground.
_The internal circuit 3 and the constant current source 4 are connected in series to an external power supply that applies _EE (-5.2V). Here, the constant current source 4 is connected to the low potential side of the internal circuit 3. Further, the clamp circuit 6 is connected in parallel to the internal circuit 3. The constant current source 4 is further composed of a current mirror circuit 51 and a current source 50 of the current mirror circuit.

Hereinafter, a power supply conversion circuit that generates the internal power supply voltage V _SS = −3.0 V will be described.

The current mirror circuit 51 is a bipolar transistor Q ₂ ~
Composed of Q ₄ . The collector of the bipolar transistor Q ₂ is connected to the V _SS terminal of the internal circuit 3, the collector of the bipolar transistor Q ₃ is connected to the current source 50 of the current mirror circuit, and the emitters of the bipolar transistors Q ₂ and Q ₃ are external low power supply V It is connected to _EE (-5.2V).

The clamp circuit 6 is composed of a bipolar transistor Q ₅ , and applies a constant voltage V _REF1 (−2.2V) to the base and connects the emitter to the V _SS pin, so that the V _SS pin is −3.0V.
It is clamped to.

That Controls variations such as voltage V _SS of the internal power supply is decreased by the constant current source 4, a constant internal voltage is obtained by clamping the variation as V _SS increases in the clamping circuit 6. Further, since the constant current source supplies a constant current to the internal circuit and the clamp circuit, it is possible to obtain a constant V _SS voltage regardless of the current flowing through the internal circuit.

In this specification, the fact that the voltage or potential becomes smaller or larger means that the positive or negative voltage or potential becomes smaller or larger as an absolute value.

 The operation of the present invention will be described with reference to FIG.

The current value I ₁ of the constant current source 4 changes in the worst condition such that the internal power supply voltage decreases (for example, when the external power supply voltage decreases and the operating temperature changes to the low temperature side, and the equivalent impedance of the internal circuit decreases). ), The internal power supply voltage is −
It is adjusted to be 3.0V.

Under the condition that the internal power supply voltage fluctuates so as to increase (when the external power supply voltage V _EE increases or the operating temperature fluctuates to the high temperature side and the equivalent impedance of the internal circuit increases), the internal power supply V _SS is changed by the clamp circuit 6. −3.0V
A constant voltage is obtained because it is clamped at. Further, since the current mirror circuit can control a large output current with a small input current, the current value flowing in Q ₂ of the constant current source 4 is Q ₃
Therefore, the value of the current flowing through the device can be small, so that the power consumption required for power conversion can be reduced.

FIG. 3 shows the fluctuation of the internal voltage V _SS when the pMOS transistor shown in FIG. 2 is used as the internal circuit 3. First
By using the power supply conversion circuit shown in the figure, internal power supply fluctuation of 5% can be achieved against external power supply fluctuation of ± 10% at room temperature of 27 ° C.
Within. In addition, temperature fluctuation (0 ℃ ~ 75
Even in the case of taking account of (° C.), the fluctuation of the internal power supply can be suppressed within 7%.

FIG. 4 shows an embodiment according to claim 2, wherein a constant voltage is obtained by increasing the current value of the constant current source when the internal power supply voltage V _SS fluctuates to be small. It is a circuit.

The potential fluctuation detection circuit 7 includes a bipolar transistor Q ₆ ,
It consists of a differential amplifier circuit consisting of Q ₇ and a constant current source I. The V _SS terminal is connected to the base of the bipolar transistor Q _6, the constant voltage V _REF2 (−3.0 V) is connected to the base of the bipolar transistor Q ₇ , and the output V _C is generated from the collector of the bipolar transistor Q _6. There is. In addition, the pMOS transistor T ₁ is connected in parallel with the current source 50 of the current mirror circuit.
Is connected, and the output V _C of the potential fluctuation detection circuit is connected to the gate.

 The operation of FIG. 4 will be described below.

When the internal power supply voltage V _SS fluctuates to be smaller than −3.0 V, the output V _C of the potential fluctuation detection circuit 7 fluctuates to the low potential side. At this time, since the pMOS transistor T ₁ becomes conductive, the current output from the current source 50 of the current mirror circuit, that is, the input current I ₀ of the current mirror circuit increases to I ₀ ′. When the constant current increases to I ₀ ′, the output current of the current mirror circuit becomes
Since it increases to I ₁ ′, the internal power supply voltage V _SS increases, that is, changes to the low potential side. When the internal power supply V _SS becomes −3.0 V or less, the clamp circuit 6 clamps the internal power supply at −3.0 V, so that a constant voltage is obtained.

FIG. 5 shows the case where the pMOS transistor shown in FIG. 2 is used for the internal circuit 3 in the power conversion circuit shown in FIG. 4 and the impedance becomes small (when the gate voltage changes from −3.0V to −3.5V). ) Shows the temperature dependence of the power supply fluctuation circuit. By using the potential fluctuation detection circuit 7 and the control circuit composed of the pMOS transistor T ₁ , fluctuations in the internal power supply can be suppressed within 10%.

FIG. 6 and FIG. 7 show a memory cell and a memory cell array, which are embodiments when a large current flows through the internal circuit 3. With the power conversion circuit shown in FIGS. 1 and 4, regardless of whether the memory cell is operating or not,
Similar to Fig. 3, when the external power supply fluctuation is ± 10% at room temperature of 27 ℃,
Internal power supply fluctuation can be suppressed within 5%.

FIG. 8 shows an embodiment of the current source 50. By switching the constant current source when the internal circuit 3 is not operating,
This is a circuit that reduces the power consumption of the entire power conversion circuit. When the internal circuit 3 is not operating, the CS signal and the MOS transistor T ₁₀ are used to switch the constant current I ₀ to the constant current I ₂ . If the constant current I ₂ is made smaller than the constant current I ₀ , the current flowing through the constant current source 4 also becomes small, so that the power consumption of the entire power supply conversion circuit can be reduced.

In the above, an example in which one potential of the external power source is commonly raised to raise the potential of the other to be the internal power source has been described, but the present invention is not limited to such a case, and one potential of the external power source is commonly used for the other. Also in the case of lowering the potential of, it can be easily applied by changing the connection of the above-mentioned embodiment or the polarity of the transistor. Also, whether the power supply voltage is positive or negative does not matter.

[Effect] As described above, according to the present invention, it is possible to obtain a power supply conversion circuit that can reduce power consumption and occupied area required for power supply conversion and that has little fluctuation.

[Brief description of the drawings]

FIG. 1 shows a first embodiment of the present invention, FIG. 2 shows an embodiment of an internal circuit, and FIG. 3 shows external power supply fluctuation dependence and temperature dependence of the power supply conversion circuit shown in FIG. It is shown. FIG. 4 shows the second embodiment of the present invention, and FIG. 5 shows the temperature dependence of the power supply conversion circuit shown in FIG. 6 and 7 show a memory cell and a memory cell array, which are examples of application of internal circuits. FIG. 8 shows an embodiment of the current source, and FIG. 9 shows a conventional reference voltage generating circuit. 1 ... Potential fluctuation detection circuit, 2 ... Limiter circuit 3 ... Internal circuit, 4 ... Constant current source 6 ... Clamp circuit, 7 ... Potential fluctuation detection circuit 8 ... Memory cell array 50 ... Current mirror circuit Current source 51 …… Current mirror circuit T _{1 to} T ₁₀ …… MOS transistor Q _{1 to} Q ₇ …… Bipolar transistor

Claims (2)

(57) [Claims] Claim: What is claimed is: 1. One terminal potential of an external power supply supplied to an LSI or the like is used as one terminal potential of an internal power supply of an internal circuit of the LSI or the like, and the other terminal potential of the external power supply is level-converted to increase or decrease. In a power supply conversion circuit for setting the other terminal potential of the internal power supply, a constant current source configured by a current mirror circuit is connected in series to the internal circuit, an external power supply voltage is applied to the series circuit, and the internal circuit A power supply conversion circuit characterized in that a clamp circuit is provided in parallel with the power supply conversion circuit. 2. The configuration of the power supply conversion circuit according to claim 1, further comprising connecting a comparison voltage input corresponding to a reference voltage input of a differential amplifier circuit to a connection point between the internal circuit and a constant current source, A power supply conversion circuit comprising a circuit for controlling a transistor connected in parallel with a current source of a current mirror circuit which constitutes the constant current source, according to an output of the differential amplifier circuit.