Programmable gain amplifier circuit capable of adjusting signal and control method thereof

Abstract

The invention discloses a programmable gain amplifier circuit capable of adjusting a signal and a control method thereof. The circuit comprises an operational amplifier, an input end, an output end, asampling capacitor, a feedback capacitor, a first switch, a second switch and a third switch, wherein one end of the feedback capacitor is connected with the sampling capacitor, and the other end isconnected with one end of each of the second switch and the third switch; the other end of the second switch is connected with the output end, and the other end of the third switch is connected with reference voltage; one end of the first switch is connected with the sampling capacitor, and the other end is connected with the output end; a reverse input end of the operational amplifier is connected with the sampling capacitor, a positive input end is connected with common-mode voltage, and the other end is connected with the output end. Through the gain amplifier circuit disclosed by the invention, the circuit design can be simplified, the design difficulty of the operational amplifier is reduced, and the power consumption and area caused by the reference voltage are saved. By modifying asampling point, the gain amplifier circuit can eliminate the offset voltage of the operational amplifier so as to realize the high-precision amplification function.

Description

technical field [0001] The invention relates to the technical field of integrated circuits, in particular to a signal-adjustable and programmable gain amplifier circuit and a control method thereof. Background technique [0002] The programmable gain amplifier circuit is referred to as PGA. It is an analog amplifier circuit that amplifies the input analog voltage signal by a set multiple and then outputs it. The amplification factor is determined by the ratio of the sampling capacitor to the feedback capacitor. The PGA circuit implemented by the switched capacitor method is fully compatible with the current standard CMOS process technology, so it is widely used in the current standard CMOS chip to amplify the analog voltage signal. [0003] figure 1 It is a typical PGA circuit application scheme. After the analog voltage signal is amplified by the set multiple after the PGA circuit, it is output to the analog-to-digital conversion (ADC) circuit, which is converted into a di...

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Problems solved by technology

[0008] image 3 The circuit shown can achieve signal amplification and regulation, but it has several obvious disadvantages: 1. Compared with the traditional PGA, a capacitor Cos is added, which increases the area; 2. Two reference voltages Vos1 and Vos2 are added, The complexity of the circuit is increased, and two noise sources Vos1 and Vos2 are also introduced; 3. The PGA loop feedback coefficient β=Cf' / (Cs'+Cf'+Cos') is smaller than that of the traditional PGA β=Cf' / (Cs'+Cf'), the reduction of the feedback coefficient leads to an increase in the design difficulty of the operational amplifier and an increase in power consumption

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