60-GHz direct-conversion gigabit modulator/demodulator on liquid-crystal polymer

In this paper, we demonstrate the first implementation of the integrated system-on-package (SOP) 60-GHz gigabit modulator and demodulator on liquid-crystal polymer (LCP). LCP provides an organic low-cost low dielectric-constant platform suitable for millimeter-wave passive design and packaging. Firstly, we demonstrate a 60-GHz planar bandpass filter and RF/baseband duplexer as the building blocks of the integrated module. Measurement results show ∼3-dB insertion loss in the bandpass filter, as well as the RF path of the duplexer, and a higher than 30-dB isolation between the baseband and RF outputs. We utilize those building blocks in the design and implemented a hybrid 60-GHz antiparallel diode-pair-based 4× sub-harmonic mixer suitable for direct up or down conversion. Measurement results indicate a better than 17-dB insertion loss with 1.25-GHz baseband bandwidth for the 4× mixer. Input 1-dB compression point of -2 dBm has been measured. Two subharmonic mixers are integrated back-to-back to perform the simultaneous binary phase-shift keying modulation and demodulation of the pseudorandom binary sequences. Eye diagrams show a better than 13-dB SNR for a data rate up to 1.5 Gb/s. 40-GHz versions of the 4× subharmonic mixer and the back-to-back chain have also been implemented. Hence, we present the first integrated millimeter-wave gigabit SOP modulator and demodulator on LCP.