JPH03188710A - Chopper amplifier circuit - Google Patents

Abstract

PURPOSE:To realize an amplifier circuit with high accuracy by using two same circuits and amplifying the differential component with distribution of charge so as to make sampling points of two input signals identical to each other. CONSTITUTION:Let a threshold voltage of an inverter 1 be Vth, and voltages Va, Vb are fed respectively to input terminals 8, 9. With switches 2, 4, 5 turned on, a voltage difference of Vth-Va is applied to a capacitor 6 connecting to the switch 4 and a voltage difference of Vth-Vb is applied to the capacitor 6 connecting to the switch 5. With the switches 2,4,5 turned off in this state and a switch 11 turned on, the charge is distributed between both the capacitors 6, a change in the voltage difference of (Vb-Va)/2 and (Va-Vb)/2 takes place in the input stage of the inverter 1, the difference is amplified by an amplification factor depending on the ratio of a capacitor 3 and a parasitic capacitance 7 and the result is outputted to respective output terminals 10.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a chopper amplifier composed of an inverter, a switch, and a capacitor.

[Conventional technology]

Figure 2 is a circuit diagram of a conventional chotsuno (amplifier circuit).
In the figure, (1) is inno (-ta) and (2) is inno (
- switch inserted between the input and output of switch (1), (3) is a capacitor installed in parallel with switch (2), (4),
(5) is a switch for switching input signals, (6) is a capacitor inserted between switches (4) and (5) and the input of inverter (1), and (7) is attached to the input of inverter (1). (8) I (9) is the input terminal, and α0 is the output terminal. FIG. 3 is a waveform diagram showing the output waveform of the circuit shown in FIG.

Next, the operation will be explained. The threshold voltage of the inverter (1) is input to the vthq input terminal (s) * (9)
It is assumed that 'Va and Wb are applied to , respectively.

First, if switches (2) and (4) are on, the input terminal of inverter (1) is vth,
A potential difference of (Vth - Va) is held in the capacitor (6). Next, switches (2) and (4) are OFF' j
,, the switch (5)], a potential difference of vb-va is generated in the capacitor (6), and this is the voltage difference between the capacitor 131
, (6) and is amplified and output.

Output voltage V of output terminal αQ. Taking the time element into consideration, ut is expressed by the following equation, and the waveform is as shown in Figure i1!3.

Vout (t) = ” (V'b(t)-Va
(t-t) )fflshi(1!3: Capacitance value of capacitor (3) c6: Capacitance value of capacitor (6) [Problem to be solved by the invention]) The conventional chopper amplifier circuit is configured as described above. Therefore, there is a problem in that the comparison points of the two input signals are shifted in time, and if there is a leak in the capacitor, the comparison accuracy deteriorates.

The present invention was made to solve the above-mentioned problems, and it is possible to set the sampling points of two input signals at the same time, and to prevent deterioration of accuracy due to capacitor leakage, etc. Another object of the present invention is to obtain a chopper amplifier circuit that can simultaneously obtain inverted and non-inverted outputs.

[Failure to solve the problem]

The chopper amplifier circuit according to the present invention uses two circuits of conventional chopper amplifiers, samples two input signals simultaneously, and then divides the accumulated charge according to the two input signal levels, thereby calculating the difference between the two input signals. The inverted and non-inverted outputs are taken out from each of the two chopper amplifiers.

[For production]

The chopper amplifier circuit according to the present invention samples two input signals simultaneously to match the time axes between the two input signals and prevent deterioration of accuracy due to capacitor leakage or the like.

Further, by using two circuits of the same chopper amplifier circuit configuration, deterioration in accuracy due to mismatch between elements such as parasitic capacitance can be prevented, and 1-inversion and non-inversion outputs can be output simultaneously.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. 1st
The figure is a circuit diagram of a chopper amplifier circuit.

In the figure, (1) to σQ are the same as those shown in the conventional example of FIG. 2, so their explanation will be omitted. αυ is a switch for distributing the charge stored in the capacitor (6).

Next, the operation will be explained. The threshold voltage of the inverter (1) is set to the vth input terminal (8), (9,1
Assume that Va and Wb are applied to respectively. And first, switch (2), (4), (
5) is i, the capacitor (6) connected to the switch (4) has a potential difference of Vth-Va, and the capacitor (6) K connected to the switch (5) has a potential difference of Vth-Vb.
A potential difference of .

In this state, when the switches (2), (4), and (5) are turned off and the switch αυ is turned on, the charge is distributed between both capacitors (6), and at the input stage of the inverter (1), each Vb-Va Va-Vt)
Nog position difference change, d=raw, c.

2 and 2 The potential difference is amplified by the amplification factor determined by the ratio of the capacitor (3) and the parasitic capacitance (7), and output to each output terminal. Since the configuration was configured to amplify the difference by distribution, 2
The sampling points of the two input signals can be made the same, high accuracy can be obtained, and there is an effect that inverted and non-inverted amplification results of the differential signal can also be obtained.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing a chopper amplifier circuit according to an embodiment of the present invention, FIG. 2 is a circuit diagram of a conventional chopper amplifier circuit, and FIG. 3 is a waveform diagram showing the output waveform of the circuit in FIG. 2. . In the figure, (1) is an inverter, (2), (4
), (5), αυ is a switch, +31, (6
) is the capacitor, (7) is the parasitic capacitance, <8), (9
) is an input terminal, and 0.1 is an output terminal. In addition, in the figures, the same reference numerals indicate the same or equivalent parts.

Claims (1)

[Claims] A switch is inserted between the inputs of two chopper amplifier circuits consisting of an inverter circuit and a switch inserted between its input and output, and the pre-charged charge is distributed by the switch to the capacitor at the input stage of each chopper amplifier. A chopper amplifier circuit characterized in that the difference between two signals is amplified and its inverted and non-inverted outputs can be obtained by amplifying the difference between two signals.