The IC Design Of High-Performance、Low-Noise Analog Front Ends

Analog Front End (AFE) which acts as the interface to amplify the weak analog signals plays an important role in nowadays analog signal processing devices. Not only the complex sensing and control systems, but also the popular portable healthcare system put forward higher requirements for the AFE. The AFE which meets the low-noise, low-offset, low power requirements with ideal input characteristics is still difficult to be designed. This thesis aims to research and design high-performance AFE.A high speed, low noise instrumentation amplifier is designed under 0.35μm 2P4M CMOS process. A Multipath Chopper-Stabilization topology with a Ripple Reduction Loop is adopted to eliminate the offset voltages, the topology avoids the bandwidth limit which occurs in traditional chopper IA topologies. The forward path compensates the doublet brought by the RRL to ensure a stable step response of the IA. The simulation results show that the PSD of the equivalent input noise lowers to be 15.1n V/Hz, The highest unity-gain bandwidth is 7MHz and the equivalent input offset or ripple voltage is lower than 20μV with a total current consumption of 265μA.An Analog Front End IC used in wearable healthcare systems is designed under 0.35μm 2P4M CMOS process. This circuit is used as the interface to read the signals of the bio-medical electrodes. An instrumentation and a Gain/BW programmable Amplifier are core modules of this circuit. The IA employs a current-feedback topology with chop modulation included and circuit optimization to improve the noise performance of this circuit. It has been silicon proved. The measurement results show that the AFE has a band-pass characteristic, its low pass corner and mid-band gain is programmable, which is digitally controlled from 150Hz to 2100Hz and 41dB-78dB respectively. The input impedance is 380MΩ@80Hz. Moreover, the CMRR is higher than 120dB@30Hz and acquires 90dB PSRR at an input’s frequency of 30Hz. The total current consumption is 7μA with a noise efficiency factor (NFE) of single channel to be 8.1.