OTA-C Differentiator for Large Time Constant Applications

In this paper a voltage differentiator based on OTA-C structure is introduced. To maintain a large time constant for biological signal processing at pico farad range filter capacitor, the input voltage attenuator is applied to reduce the overall transconductance gain of this OTA. This OTA-C voltage differentiator is simulated on a standard CMOS 0.35 mu m process and operated at 1.2 V with 4.8 nW power consumption. On comparison with the previous work which utilised a current conveyor topology as a voltage differentiator, the OTA-C differentiator dramatically reduces the size of the total capacitance which is preferable for integrated circuit implementation.