A Low Power CMOS Analog Front-End Circuits for Sensor Output

This paper describes a low-voltage and low-power analog front end using pre-amp for Sensor Output. The continuous time, discrete amplitude systems combine benefits associated with analog and digital systems. The proposed device consists of a multi-scale transresistance continuous time amplifier followed by a 6-bit incremental A/D converter. The circuit selects automatically the scale to use for each measurement and includes two digital-to-analog converters for the calibration of offset and gain of each scale. The PGA has a voltage gain varying from 0 to 65㏈, while maintaining a constant bandwidth. The proposed interface circuit achieves a measurement accuracy almost always better than 1% over a sensor resistance range of more than 4 decades. The chip has been realized with a 0.18㎛ 1P6M n-well CMOS process. They consume 3.2㎽ from a 1.8V power supply and occupy an area of 0.19㎟.