A 2.7 GHz super-regenerative receiver front-end for QPSK modulated signals

Abstract

In this paper, the operation of superregenerative (SR) receivers based on super-regenerative oscillators (SRO) is extended to enable the detection of QPSK modulated signals rather than traditional implementation of SR receivers to detect OOK signals. The ability of super-regenerative receivers to properly detect QPSK modulated signals enables using the benefits of such receivers of high gain and low power for current mainstream receivers for wireless sensor networks applications. For this purpose, a low power superregenerative front end is proposed, it is composed of an LNA and (SRO) merged for current-reuse and operating at 2.7 GHz. The front-end embedded in a downconversion receiver demonstrates that SRO phase preserving property enables proper detection of QPSK modulated signal while consuming an average power of 0.54 mW from a 0.65 V supply at a bit rate of 4 Mbps equivalent to 135 pj/bit.

A Superregenerative QPSK Receiver

“…A more detailed analysis is given in [16], without underlying assumptions and covering also the SRO in the logarithmic mode of operation, and showing that the main conclusion of (5) is still valid. Now, from a pure signal processing point of view, the SRO signal s(t) could be demodulated by a conventional PSK detector, using IQ downconversion as suggested in [14]. However, in a practical implementation, the radiation from the oscillator required for downconversion would mask the input signal.…”

“…However [14] reports the design and simulation of an approach for SR QPSK detection: The SRO is used as a simple front-end amplifying and filtering the input signal while preserving phase information. The scheme suggested in [14] includes a conventional IQ demodulation chain. Besides no experimental verification, this approach has two significant drawbacks which can not be overlooked.…”

Superregeneration Revisited: From Principles to Current Applications

“…The complexity of the required digital hardware is orders of magnitude simpler than with conventional IQ receivers and allows building of complete BPSK, QPSK, or 8PSK receivers [41] with very few resources, without spoiling the main point of SR reception: simplicity. The same net effect can be achieved by sampling several RCdelayed versions of the SRO output [42]- [44].…”