Programmable negative capacitance circuit for improving input impedance of programmable gain chopping instrument amplifier

The invention discloses a programmable negative capacitance circuit for improving the input impedance of a chopping programmable gain instrumentation amplifier (CFPGA), and provides the chopping programmable gain instrumentation amplifier (CFPGA) with an input impedance improving circuit, and the whole circuit consists of a secondary operational amplifier, a chopping modulator working at 10Khz and the input impedance improving circuit. And the output end of the negative capacitor is connected to the upper pole plate of the input capacitor Cin. The input capacitor is a 7-bit binary programmable capacitor, and 7-bit adjustment can be completed. According to the CFPGA circuit, the input impedance is synchronously improved while gain adjustment is carried out, and compared with a traditional pre-charging input impedance improving technology, extra noise cannot be generated, so that the final CFPGA circuit achieves the functions of high input impedance and low noise. By using the programmable negative capacitance