Design considerations for high performance very low frequency filters

This paper deals with the design of very low frequency continuous time filters based on Operational Transconductance Amplifiers (OTAs). Design techniques for both high-performance OTAs and large capacitors are presented. Very small transconductance OTAs with low noise levels and small harmonic distortion components are discussed. Large capacitors are implemented by using impedance scalers based on current mirrors. Design strategies and simulated results for a sixth order 1 Hz lowpass filter are presented.