A low distortion transmit-receive antenna switch for mobile 'phones

摘要

A low-distortion transmit-receive switch for a GSM or UMTS cellphone has a series-shunt arrangement in which the series switching arms each comprise a number of serially connected FETs 11. This provides a high blocking voltage while permitting a low gate drive voltage. However, the FETs in the "OFF" switch arm have a highly nonlinear capacitance, which distorts the switched signal. To overcome this problem at least one node between the FETs is coupled by a high value resistor 18 to a signal line 15 bridging the FETs.