Design Of Low Noise Specific Instrumentation Amplifier

In recent years, the medical electrical equipment has grown more than 10%, which is caused by the population explosion and the aging of population, also with the buildup of health consciousness. And low power, high performance analog devices are the kernel part of the medical electrical equipment. It is urgent to research the low noise instrument amplifier, because it is the important part of the detection and magnify of weak bioelectricity signals. This paper aims at investigating and realizing an ASIC cell of low noise instrumentation amplifier based on the standard CMOS process, which is employed in the Analog Front-End as a part of SOC.An instrumentation amplifier is a closed-loop gain block that has a differential input and an output that is single-ended with respect to a reference terminal. It must amplify the differential input accurately and suppress any unwanted common-mode signals. Low noise is the most important feature of low noise instrumentation amplifier. The low noise specific instrumentation amplifier has higher performance than three op-amp and current structures, also it has compact structure and is easy to implement.In this paper, a low noise specific instrumentation amplifier is designed to use for weak bioelectricity signals magnification and main research content about the circuit are as follows:1. The reduction of noise technology is discussed and chopper stabilization technology is chosen for the circuit.2. Second order band-pass filter is used to reduce the residual offset which is produced by the nonideal feature of modulator.3. Rail-to-rail input of modulator and preamplifier is realized to meet the requirement of common mode input range.The proposed instrumentation amplifier chip is implemented by the 0.35μm CMOS process of TSMC with die area of 980μm×450μm. The test results show that the low noise amplifier features a open loop gain of 100 dB and a bandwidth of 10 kHz. The equivalent input noise is about 27.2 nV/sqrt(Hz). The simulation and test results show the low noise instrumentation amplifier based on chopper stabilization is a potent Analog Front-End.