Realisation of second order log filter with OTA using state space representation

CMOS Operational transconductance amplifier (OTA) based second order linear and log domain filter synthesis from state space representation are reported. The proposed structure shows that from a single circuit three basic filtering functions can be obtained from three different nodal outputs in suitable condition. Center frequency, 3dB bandwidth and quality factor can be adjusted by tuning the transconductance of the OTA. Implementation of log domain filter shows higher dynamic range. Simulation results veryfying the theoritical analysis of the proposed filter structure are included.