Six‐port QPSK demodulator for optimal K‐band multiport amplifier calibration

Abstract

A wideband six-port-based demodulator is proposed and applied as a quadrature phase shift keying (QPSK) demodulator for optimal K-band multiport amplifier (MPA) calibration circuitry. The proposed six-port demodulator adopts wideband ring hybrids for optimal 180°p hase balance in local oscillator signal paths. In addition, a voltagecontrolled reflection-type phase shifter and an attenuator are integrated into the six-port structure to ensure accurate magnitude and phase balance over broadband operation, resulting in optimal phase and amplitude error detection for the MPA system. To verify the proposed structure, RF demodulation of the K-band QPSK modulated signal was demonstrated for purpose of MPA calibration.

System Analysis of Six-Port-Based RF-Receivers

“…Comparable six-port topologies (but without path mismatch cancellation) have also been the most selected ones for practical implementations, e.g. [6], [9].…”

“…In this respect, six-port based analog receivers seem to possess the required potential. These gained a lot of research interest in last years [3], [6], [7] also with respect to system modeling and calibration [8], [9]. The multiport receivers comprise several advantages compared to conventional mixerbased topologies, e.g.…”

Power amplifier linearisation using digital predistortion and multi‐port techniques

“…Recently, there has been much interest in using multiport structures in communication devices [29,31,32]. Many studies have been done on demodulators where a six (five)-port configuration is used together with power detectors to generate the baseband in-phase (I ) and quadrature-phase (Q) data [33][34][35][36][37]. The advantages of such an approach are many and various, make it a superior choice with respect to their heterodyne counterparts.…”

Dual-Band Direct Conversion Receiver With Additive Mixing Architecture

“…Some DCRs based on the six-port techniques were also proposed for software defined radio (SDR) front-ends [4]- [6]. Other six-port applications can be also found in calibration circuitry and discriminator [7], [8]. This broad scope of applications is possible because the advantages of additive mixing by…”