A 2.7-V elliptical MOSFET-only C-gm-OTA filter

The g(m) C-operational transconductance amplifier (OTA) technique relaxes t ransconductor output swing and de-gain requirements; which makes it a suita ble candidate for low-voltage circuits. To reduce the power consumption of OTA's, an excess phase-shift compensation with all automatic tuning circuit is used. A floating triode-region transconductor with a novel biasing to c ompensate the effect of channel-length modulation is presented. The two ind ependent common-mode levels in a g(m) C-OTA integrator are utilized to bias a MOS as a linear capacitor. This enables the realization of the floating- transmission zero capacitors with a pure digital CMOS process. The implemen tation and the experimental results for a third-order 2.7-V all-MOS ellipti cal filter with 64-dB dynamic range and 0.1% linearity are presented.