Design of the Wideband Active RF TX Router

Abstract

A $2\times 2$ wideband active RF TX router is proposed to increase peak data rates and use fragmented spectrum efficiently. The proposed router can separate and aggregate carriers for 4G/5G applications, and its configuration contains two cascaded sections. The first section consists of four parallel channels, each comprising a single-pole single-throw (SPST) switch and a resistive-feedback inverter-type amplifier. The second section is composed of two identical cascode amplifiers arranged in parallel. The proposed router with this combination offers two operating modes: separation and aggregation, each consisting of two types, with impedance matching across different modes. In addition, the proposed router provides isolation among different channels and reverse isolation within the same channels. Design equations and procedures are also developed for the proposed router with its two operating modes. An example realized in the standard 0.18- $\mu $ m CMOS process is presented. The observed results demonstrate that the proposed router achieves an average gain of −1 and −1.5 dB in the frequency ranges of 0.5–4.55 GHz and 0.52–4.62 GHz, respectively, with input and output return loss higher than 8 dB for separation and aggregation modes, respectively. The output 1-dB gain compression point (OP $_{1\,\text {dB}}$ ) ranges from −1.73 to 1.93 dBm and −1.9 to 1.5 dBm for separation and aggregation modes, respectively. The isolations, among different channels and within the same channels, are better than 27 and 20 dB for separation and aggregation modes, respectively.