A multi-channel wideband direct-conversion receiver using synchronization signal from a tunable injection locked oscillator

Abstract

Synchronization is a challenging issue facing industrial designers that has not been researched often by academic researchers. The conventional techniques are phase-locked loop (PLL), digital PLL, or direct-digital synthesis (DDS). With any one or a combination of these techniques, high performance can be achieved at the expense of complexity or cost. In this paper, another technique, the injection locking technique, is explored to provide synchronization for a direct-conversion receiver. More specifically, signal synchronization is achieved with a selectable dielectric-resonator injection locked oscillator (DRILO) designed at a free running frequency of 3.634 GHz. The receiver developed was able to recover the carrier and IQ signals from 3.58 GHz, 3.63 GHz and 3.69 GHz with 50 Msps to 63 Msps QPSK modulated signals. The receiver designed as such is novel and simple, and can find applications in many modern communications such as WiMax. It can also overcome frequency synchronization problems faced in OFDM systems.