A 20–43.5-GHz Wideband Tunable Silicon Photonic Receiver Front-End for mm-wave Channel Selection/Jammer Rejection

This article presents a 20–43.5-GHz mm-wave silicon photonic reconfigurable receiver (RX) front-end (FE) for wideband mm-wave 5G systems. The wideband front-end consists of an input electro-optic (E/O) converter, a silicon photonic integrated circuit (PIC), and an output opto-electric (O/E) converter. The silicon PIC is programmable either as a mm-wave band-pass filter (BPF) for channel selection and jammer rejection or as a mm-wave notch filter for jammer rejection in adjacent and alternate channels. Both the BPF and notch filter center frequencies are continuously tunable over a 20- and 43.5-GHz range, with the BPF bandwidth also configurable between 4.7-6-GHz. In order to show the effect of in-band jammer rejection on improving system linearity and overall received signal quality, a 4-channel system is demonstrated with the BPF configured with 5-GHz 3-dB bandwidth. The whole mm-wave system is optimized for minimum noise figure ( $NF$ ), maximum linearity (third-order input intercept point ( $IIP_{3}$ ) and input 1-dB compression power ( $IP_{\text{1}\,\text{dB}}$ ), and maximum signal to noise ratio (SNR) through modulator bias control and optical amplification. An IM $_{3}$ reduction, and thus IIP $_{3}$ improvement, of 22.5- $\text{dB}$ is achieved. This yields an average error vector magnitude (EVM) improvement of 4.5- $\text{dB}$ at 20-GHz and 50- $\text{Msps}$ 16-quadrature amplitude modulation (16-QAM), with an overall EVM of −25.5- $\text{dB}$ . To the best of the authors' knowledge, this is the first silicon photonic implementation of a wideband reconfigurable mm-wave RX that covers the entire mm-wave sub-45-GHz band.