Differential-input buffered and transconductance amplifier-based all-pass filter and its application in quadrature oscillator

The paper deals with a novel all-pass filter circuit employing Differential-input Buffered and Transconductance Amplifier (DBTA), two grounded resistors and two grounded capacitors. The proposed all-pass filter functionality is demonstrated on its application in quadrature oscillator, which provides a couple of both voltage and current output signals shifted in phase by 90° and equal in amplitude. The frequency of oscillation can be set independently on the oscillation condition. Theoretical behavior of the all-pass filter as well as the whole quadrature oscillator have been verified using PSpice simulation.