Low-voltage first-order fully differential CMOS all-pass filter with programmable pole-zero

A simple modification of the conventional first-order all-pass filter is introduced that provides it with a low-voltage fully differential operation with programmable pole-zero frequency. The modification is based on the inverting op-amp configuration and uses operational transconductance amplifiers instead of resistors not needing a buffered signal source or buffered op-amps as the conventional all-pass does. Experimental results verify that tuning capability is provided.