A wideband 0.6dB insertion loss +20.5dBm P1dB CMOS T/R switch

This paper provides a detailed analysis of performance limitations in RF CMOS T/R switches, and proposes a novel method to improve the insertion loss and power handling capability by dynamically biasing the body and the gate of the switch transistors to make the device operating in linear region under large signals. The concept is implemented with circuits only and no inductor is used. A prototype was designed and implemented in standard 0.18-μm CMOS technology. The experimental results show 0.6dB insertion loss at 2.4GHz, 20.5dBm P1dB for the transmitter path of the T/R Switch with a single 1.8V control voltage. The die area excluding IO pads is 0.14mm by 0.12mm. The performance meets the requirements of most mobile wireless communication systems.

I. Introduction

T/R switch is employed in various wireless communication systems for time multiplexing between transmitter and receiver. With this topology, transmitter and receiver are powered on alternatively which saves the overall system power consumption and reduces the interference between the transmitter and the receiver. It has been adopted in most of the mobile wireless communication systems such as wireless LAN, Bluetooth, cellular PCS/CDMA/WCDMA/TDMA/GSM, and so on. A high quality RF switch in wireless communication systems is required to have low insertion loss, high power handling capability and high isolation. Low insertion loss minimizes the receiver sensitivity degradation and transmitter's output power loss induced by the switch. Power handling capability of a RF switch is specified by the transmitter's maximum output power in a system. High isolation is to minimize the interference from the switch-on path to the switch-off path and vice versa. For mobile wireless communication devices, insertion loss and power handling are the most challenging requirements for a CMOS T/R switch.