Cognitive Polar Receiver Using Two Injection-Locked Oscillator Stages

Abstract

A novel cognitive polar receiver that utilizes two injection-locked oscillator stages to extract the modulation envelope and phase components of a received nonconstant envelope modulation signal without using phase-locked-loop-based carrier recovery circuitry is presented. The paper begins with a theoretical analysis of injection locking and pulling phenomena based on the discrete-time computation approach, and then develops the principles of the proposed receiver. The implemented prototype can cover a sensing bandwidth of 140 MHz at a central frequency of 2.43 GHz and perform π/4 differential quadrature phase-shift keying and quadrature phase-shift keying demodulation with the best error vector magnitudes of 6.6% and 7.9%, respectively, both at a symbol rate of 2 Ms/s. Due to its simplicity, the proposed receiver has great potential as an energy-efficient architecture with low complexity for short-range wireless communications.