Integrated circuit incorporating RF antenna switch and power amplifier

#The present invention relates generally to Radio Frequency (RF) communications systems and more particularly relates to an RF antenna switch constructed utilizing Field Effect Transistors (FETs) configured with floating substrate terminals wherein the switch and associated power amplifier are constructed in the same integrated circuit.

#Currently, high frequency radio frequency (RF) communications are becoming increasingly prevalent. Products touting wireless RF communication links are becoming increasingly popular among consumers. Today, there are an increasing number of new products, in addition to existing products being revamped that are being designed to incorporate wireless RF links.

#Due to the explosive consumer demand for products sporting wireless communication links, there is a need for low cost transceivers that are suitable for mass manufacture. In most wireless applications, especially those designed to be mass-produced for the consumer market, it is desirable to reduce both the size and cost of wireless transceivers as much as possible. In the case of time division duplex (TDD) transceivers, manufacturers are constantly striving to reduce the size and cost of the power amplifier and transmit/receive antenna switch portions of the transceiver by integrating these functions onto a single low cost integrated circuit.

#The invention is herein described, by way of example only, with reference to the accompanying drawings, wherein:

#FIG. 1 is a schematic diagram of a circuit used to model a field effect transistor utilizing ideal components;

#FIG. 2 is a schematic diagram of an example RF antenna switch constructed using FETs with substantially floating substrates in accordance with the present invention;

#The following notation is used throughout this document. 1 Term Definition CMOS Complementary Metal Oxide Semiconductor DC Direct Current FET Field Effect Transistor IC Integrated Circuit ISM Industrial Scientific Medical frequency band PA Power Amplifier RF Radio Frequency RFIC Radio Frequency Integrated Circuit TDD Time Division Duplexing WLAN Wireless Local Area Network

#The present invention is a transmit/receive antenna switch capable of being integrated using silicon based RF CMOS semiconductor processes whereby the substrate (i.e. bulk) terminals of the FETs are left floating thus improving the isolation and reducing the insertion loss of the switch.

#A schematic diagram of a circuit used to model a field effect transistor utilizing ideal components is shown in FIG. 1. The model of the FET, generally referenced 10, comprises an ideal field effect transistor 12 having a gate, source, drain and substrate terminals with resistances represented by RG, RS, RD and RSUB, respectively. Parasitic capacitances between gate-drain, gate-source, gate-substrate and drain-source are modeled as CGD, CGS, CGB and CDS, respectively. Gate to substrate resistance is represented as RCGB located in series with the gate-substrate parasitic capacitance CGB.