Active compensation of operational transconductance amplifier filters using partial positive feedback

An active compensation technique for improving high-frequency performance in OTA-C filters is presented. Each critical OTA is replaced by two OTAs connected in parallel with opposite polarity and with different transconductances. The novel feature of this technique is that it does not require tuning to reduce excess phase and yields filters with extended tuning ranges. It is demonstrated by a programmable bandpass filter from 1 to 9 MHz fabricated in 3- mu m CMOS technology.<
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