Tunable 1^st Order IIR Phase Shifter Design and Implementation

This paper presents a new phase shifter which is a first-order infinite impulse response (IIR) filter that can shift phase both in phase-lead <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$(0^{\circ}\ \text{to}+180^{\circ})$</tex> and phase-lag <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$(-180^{\circ}\ \text{to}\ 0^{\circ})$</tex> fashion. Moreover, continuous phase tuning is also proposed in our phase shifter. The z-transform pair of phase-shifted cosine signal is utilized as the origin, then factorization of such term can give transfer function of first-order IIR phase shifter. The filter structure realization of the tunable phase shifter will be shown and applied with a digital cosine oscillator. Both simulation and hardware experiments can show phase-shifted signals in real-time controlled by phase-tuning parameters compared with a cosine reference signal as a demonstration. The allpass phase shifter will be used as a benchmark, and trade-off analysis using the proposed phase shifter will also be discussed.