Design of low frequency highpass filter using pseudo resistors

Design of low frequency high pass filters using pseudo resistors is discussed in this paper. The pseudo resistor, which is biased in the sub-threshold region, is capable of achieving very large value resistance while keeping silicon area very small. Designs of first and second order high pass filters with cut off frequency of 0.01 Hz are presented. This work discusses the challenges faced while designing the high pass filter, the concept of pseudo resistors to overcome theses problems and finally the completed design of the filter with smallest silicon area.