A Frequency Reconfigurable Transceiver Front-End With Enhanced Out-of-Band-Rejection and High Phase Resolution for 5G mm-Wave Phased Arrays

Abstract

This article introduces a frequency reconfigurable transceiver (TRX) front-end (FE) for phased-array systems supporting 5G frequency range 2 (FR2) 24–28 and 37–40 GHz bands. Novel passive and active frequency reconfigurable networks (FRNs) based on path-selective concepts are proposed and utilized in the power amplifier (PA) and low-noise amplifier (LNA) to realize frequency reconfigurability and good out-of-band rejection. The FE employs a local-oscillator (LO) phase-shifting architecture to realize multiband operation and wideband accurate phase shifting while relaxing LO phase shifter (PS) bandwidth requirements. To enhance the phase resolution, the pMOS varactor compensation technique and layout-flexible transmission line phase shifter (TLPS) are adopted in the 7-bit vector-summing phase shifter (VSPS) to achieve <1° rms phase error. High-gain path-reconfigurable LO buffer (LOB) is introduced to reduce LO chain power consumption and chip area overhead. Fabricated in a 65-nm CMOS process, the transceiver FE has a core area of 0.78 mm2. Thanks to the proposed techniques and measurements, the FE can deliver a maximum saturated output power of 17.7 and 16.4 dBm, peak power added efficiencies of 19.3% and 12.1% at 27 and 38 GHz, respectively, while maintaining a minimum noise figure (NF) of 6.5 and 8.1 dB at 27 and 37 GHz. An image-rejection ratio (IMRR) of 22.8–43.4 and 37.3–57 dBc can be maintained for transmitter (TX) and RX, respectively. With a 100 MSym/s 64-quadrature amplitude modulation (QAM) modulated signal, this FE can achieve an average output power of 8.23 and 6.9 dBm at 26 and 39 GHz with the adjacent channel power ratio (ACPR) of −25.46 and −25.04 dBc, respectively. Moreover, in the RX mode, this FE can support a maximum 4.8 Gb/s data rate transmission with about −37 dB EVMrms.