Design of signal processing chip based on weak current sampling

This article proposes a signal processing circuit based on weak current signal acquisition. The circuit mainly includes a programmable gain amplifier (PGA) at the front end and a high-performance Sigma Delta modulator module. For the weak current signal output by the sensor, a PGA circuit based on switch capacitor feedback is used to collect and amplify the signal. The modulator adopts a single loop second-order feedforward three-bit quantization structure to meet the high-precision requirements of the system. The system is based on the standard CMOS smic18mmrf process to complete the overall circuit design. With a power supply voltage of 3.3V, the circuit can achieve 13.5 effective bits (ENOB) and 82.7dB signal-to-noise ratio (SNR) within a 10Hz signal bandwidth.