Analysis and Design of a Fully-Integrated High-Power Differential CMOS T/R Switch and Power Amplifier Using Multi-Section Impedance Transformation Technique

Abstract

In this paper, a new topology for a high-power single-pole-double-throw (SPDT) antenna switch is presented, and its loss mechanisms are fully analyzed. The differential architecture is employed in the proposed switch implementation to prevent unwanted channel formations of OFF-state Rx switch transistors by relieving the voltage swing over the Rx switch devices. In addition to that, the load impedance seen by the Tx switch is stepped down to reduce the voltage swing even more, allowing the antenna switch to handle a high-power signal without distortions. To drop the switch operating impedance, two matching networks are required at the input and the output of the Tx switch, respectively, and they are carefully implemented considering the integration issue of the front-end circuitries. From the loss analysis of the whole signal path, an optimum switch operating impedance is decided in view of a trade-off between power handling capability and insertion loss of the antenna switch. The insertion loss of the proposed design is compared to the conventional design with electromagnetic (EM) simulated transformer and inductors. The proposed antenna switch is implemented in a standard 0.18 µm CMOS process, and all switch devices adopt the deep n-well structure. The measured performance of the proposed transmitter front-end chain shows a 1 dB compression point (P1dB) of 32.1 dBm with 38.3% power-added efficiency (PAE) at 1.9 GHz.