A fully balanced pseudo-differential OTA with common-mode feedforward and inherent common-mode feedback detector

A pseudo-differential fully balanced fully symmetric CMOS operational transconductance amplifier (OTA) architecture with inherent common-mode detection is proposed. Through judicious arrangement, the common-mode feedback circuit can be economically implemented. The OTA achieves a third harmonic distortion of -43 dB for 900 mV_pp at 30 MHz. The OTA, fabricated in 0.5-μm CMOS process, is used to design a 100-MHz fourth-order linear phase filter. The measured filter´s group delay ripple is 3% for frequencies up to 100 MHz, and the measured dynamic range is 45 dB for a total harmonic distortion of -46 dB. The filter consumes 42.9 mW per complex pole pair while operating from a ±1.65-V power supply.