The application of all-pass filters in the design of multiphase sinusoidal systems

The design of even and odd phase sinusoidal systems using all-pass networks is presented. The all-pass network has the unique characteristic of unity gain at all frequencies and a frequency-dependent phase relationship between output and input. It produces up to 180 degrees phase shift which allows the easy implementation of multiphase systems. The network is implemented using the widely available operational amplifier which results in low harmonic distortion, low frequency error, large output voltage swing and low output impedance from a simple structure. The operating frequency is limited only by the gain-bandwidth product of the op-amp. (C) 1999 Elsevier Science Ltd. All rights reserved.