A Low-Input Current Chopper Amplifier

A Low-Input Current Chopper Amplifier

Chava, B.C.

Makinwa, K.A.A. (mentor)

Electrical Engineering, Mathematics and Computer Science

Microelectronics & Computer Engineering

2012-03-30

This thesis describes the implementation of a low input-current chopper amplifier. Chopper amplifiers are attractive in applications where high DC precision is required, due to their low offset, drift & 1/f noise. They are generally used in the analog signal chain to boost weak sensor signals and buffer them to an analog-to-digital converter. Till recent years, research related to chopper amplifiers has focused on techniques to reduce their low frequency voltage errors and exploring effective techniques to suppress chopper-ripple. A superior performance on both these fronts has been achieved. However, at the cost of significantly large input currents (>100pA) and input current noise (>100fA/ Hz), thus limiting their usage to sensors with low source impedance (<10k?). In this work, a novel input-chopper architecture is proposed, implemented and measured. It achieves a 2.5X improvement in input-current compared to the state-of-the-art in chopper amplifiers with a singlepoint trim. The proposed technique also reduces the common mode variation of the input current to 4.5pA/V, which is an indication of a high common mode rejection ratio in a high source impedance (>1M?) application.

http://resolver.tudelft.nl/uuid:a76910ef-0f00-4128-8495-bb70ff985b31

2012-07-19

Student theses

master thesis

(c) 2012 Chava , B.C.