Injection-Locked Phase-Locked Loop for BPSK Coherent Demodulation: Theory and Design

In this paper for the first time the use of injection-locked phase-locked loop (ILPLL) for the BPSK to ASK coherent conversion is explored. Two circuit architectures are proposed, one using two second-harmonic ILPLL (SH-ILPLL) and the other using a single SH-ILPLL. In the case of two SH-ILPLL, feedback loop amplifiers are used and an increase of 20 times in the locking range of the converter is achieved. In the case of the single SH-ILPLL, direct BPSK to ASK conversion is also achieved but found with smaller locking and dynamic ranges. However, it is very simple and easy to develop. With the addition of an envelop detector, both circuit architectures can be used as a complete and compact RF front-end receiver that can direct demodulate digital RF/microwave signals without many intermediate components and devices. Such a low-cost and low-complexity receiver can be employed in many wireless applications such as RFID and sensor networks.