JPH0770965B2 - Semiconductor integrated circuit - Google Patents

Description

The present invention relates to a semiconductor integrated circuit, and more particularly to a semiconductor integrated circuit including an analog arithmetic circuit.

[Outline of Invention]

According to the present invention, in a semiconductor integrated circuit including an analog operation circuit, the reference voltage input circuit of a plurality of analog operation circuits having signal input terminals and output terminals independent of each other is configured by a switched capacitor circuit, so that the same analog reference voltage is obtained. It is possible to perform conversion from the voltage generation circuit to any reference voltage required by each analog operation circuit by simply changing the capacitance value of the capacitance included in the reference voltage input circuit, and no voltage conversion circuit is required. By sharing the reference voltage generation circuit, high integration and low power consumption can be realized at the same time.

[Prior art]

FIG. 2 shows the most common supply method for supplying different reference voltages to a plurality of analog arithmetic circuits having independent signal input terminals and output terminals in a conventional semiconductor integrated circuit.

In the circuit configuration shown in the figure, the signal input terminals 3i (hereinafter i = 1 to n, which are independent of each other) of the output voltage a of the reference voltage generation circuit 1 are
n; be an integer. ) And the voltage level converting circuit 8i for converting the reference voltage b _i required in the analog operation circuit 6i is interposed between the reference voltage generation source 1 and the analog operation circuit 6i having an output terminal 7i.

[Problems and Objectives to be Solved by the Invention]

However, in the above-mentioned conventional technique, not only the circuit scale increases due to the level conversion, but also an operational amplifier is required for amplification of the reference voltage level and impedance conversion, and power consumption due to resistance division or the like increases. Due to the increase, there has been a problem that the range of the reference voltage that can be used in each analog arithmetic circuit is limited and the dynamic range becomes narrow.

The present invention greatly improves such a problem, and an object of the present invention is to set an arbitrary reference voltage to be supplied to a plurality of analog arithmetic circuits having mutually independent signal input terminals and output terminals to the same reference voltage. While sharing the generation circuit,
Moreover, the object is to provide a semiconductor integrated circuit capable of achieving high integration and low power consumption at the same time by realizing without the intervention of a level conversion circuit as in the prior art.

[Means for solving problems]

The semiconductor integrated circuit of the present invention is a semiconductor integrated circuit having an analog arithmetic circuit having a plurality of input terminals, and is a switched capacitor circuit having a capacitive element as a component of the circuit, and its output terminal is a first analog arithmetic circuit. A first input circuit connected to the first input terminal of the switch and a switched capacitor circuit having a capacitive element as a component of the circuit, the output terminal of which is the second input terminal of the first analog arithmetic circuit. A third input circuit connected to the first input terminal of the second analog arithmetic circuit, and a second input circuit connected to the second analog operation circuit, and a switched capacitor circuit having a capacitive element as a component of the circuit. An input circuit and a switched capacitor circuit having a capacitive element as a component of the circuit, the output terminal of which is the second analog operation circuit. A fourth input circuit connected to the second input terminal, and having a reference voltage source for applying the second input circuit and the reference voltage to the input terminal of the fourth input circuit.

[Action]

According to the above configuration of the present invention, by changing the capacitance value of the capacitance included in the input circuit connected to the reference voltage input terminal of each analog arithmetic circuit, it flows into the analog arithmetic circuit via the reference voltage input circuit. The charge is controlled, and it can be regarded equivalently that any reference voltage is equivalent to being applied to the reference voltage input terminal, and the polarity of the applied voltage depends on the timing of operating the analog switch of the input circuit. Also, the level conversion circuit required in the past is not necessary at all, and the reference voltage can be shared, so that the circuit scale can be reduced and the power consumption can be reduced. It is a thing.

〔Example〕

FIG. 1 (a) is a diagram showing a method of supplying a reference voltage according to an embodiment of the present invention, which is a case where two signal input terminals and two output terminals are independent of each other. Further, FIG. 1 (b) is a diagram showing an input circuit portion of the analog arithmetic circuit of FIG. 1 (a).

Hereinafter, detailed description will be given based on examples.

In FIG. 1A, the output signal a of the reference voltage generating circuit 1 is the signal input terminals 31 and 32 and the output terminal 7 which are independent of each other.
It is inputted to the reference voltage input circuits 51, 52 via the reference voltage input terminals 21, 22 of the analog arithmetic circuits 61, 62 having 1, 72.
At this time, if the opening and closing an analog switch S1~S8 at appropriate timing in the circuit shown in Fig. 1 (b), is charged to the input capacitance B ₁ and B ₂ charge _{V in, C 1, V r} · C 2 (Where C
_1, C ₂ is the capacitance value of B _1, B _2, the V _in the input signal voltage, Vr is the output voltage of the reference voltage generating circuit), as the transfer charge to the feedback capacitor B ₀ of the operational amplifier A, Therefore, the equivalent Vr can be arbitrarily changed by changing the input capacitance ratio (C ₂ / C ₁ ) of the analog arithmetic circuit.

Therefore, in the circuit configuration of the present invention, the apparent reference voltage can be arbitrarily set only by changing the capacitance value of the input circuit without the conventional voltage conversion circuit. The generation circuit can be shared.

〔The invention's effect〕

As described above, according to the present invention, not only the voltage level conversion circuit which has been conventionally required is not required at all while sharing the same reference voltage generation circuit, but also the optimum reference voltage can be set in each analog operation circuit. Therefore, the circuit size is small such that the dynamic range is not reduced, and the power consumption can be reduced, which is advantageous for integration.

In the embodiment of the present invention, an example in which there are two signal input terminals and two output terminals independent of each other has been described.
Various other cases are conceivable without departing from the gist of the present invention, and the circuit transfer function of the analog arithmetic circuit is not limited.

[Brief description of drawings]

FIG. 1A is a diagram showing an embodiment of the present invention. FIG. 1 (b) is a diagram showing an input circuit section of the analog arithmetic circuit in FIG. 1 (a). FIG. 2 is a diagram showing a conventional example in the case of supplying an arbitrary reference voltage to the analog arithmetic circuit. 1 ... Reference voltage generation circuit 2,2i ...... Reference voltage input terminal for analog operation circuit 3,3i ...... Signal input terminal for analog operation circuit 41,42 …… Signal input circuit for analog operation circuit 51,52 …… Analog Reference voltage input circuit for arithmetic circuit 6,6i …… Analog arithmetic circuit 7i …… Output terminal of analog arithmetic circuit 8i …… (voltage) level conversion circuit a …… Output voltage of reference voltage generation circuit bi …… (voltage) level Output voltage of conversion circuit B ₀ , B ₁ , B ₂ ...... Capacity S ₁ , S ₂ , S ₃ , S ₄ , S ₅ , S ₆ , S ₇ , S ₈ ...... Analog switch A ...... Operational amplifier

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masao Shindo 3-5 Yamato, Suwa City, Nagano Prefecture Suwa Seikosha Co., Ltd. (56) Reference JP-A-61-39615 (JP, A) 56-85463 (JP, U)

Claims (1)

[Claims] 1. A semiconductor integrated circuit having an analog arithmetic circuit having a plurality of input terminals, which is constituted by a switched capacitor circuit having a capacitive element as a constituent element of the circuit, and whose output terminal is the first analog arithmetic circuit. A first input circuit connected to an input terminal of the switch and a switched capacitor circuit having a capacitive element as a component of the circuit, the output terminal of which is connected to the second input terminal of the first analog operation circuit. And a third input circuit having a switched capacitor circuit having a capacitive element as a component of the circuit and having an output terminal connected to the first input terminal of the second analog operation circuit. A switched capacitor circuit having a capacitive element as a component of the circuit, the output terminal of which is the second input of the second analog operation circuit. A semiconductor integrated circuit comprising: a fourth input circuit connected to a terminal; and a reference voltage source that applies a reference voltage to the input terminals of the second input circuit and the fourth input circuit.