GaAs analog switch cell with wide linear dynamic range from DC to GHz

摘要

Improved series and shunt switching cells for selectively switching an RF input signal to an output over a wide range of frequencies and in a linear manner. The series cell includes an input FET which has the source electrode clamped by means of a diode clamping circuit. The diode clamping circuit is in series with a second FET which has applied to the gate electrode a control voltage. A third FET has its source electrode connected to the source electrode of the second FET and has the drain electrode coupled through a diode to the drain electrode of the second FET. The drain electrode of the third FET is coupled to the gate electrode of a fourth FET where the source electrode of the fourth FET controls a series switching FET to enable the input signal to be switched to the output. The series switching FET has its source to drain path in series with a gate electrode of a fifth FET with the source electrode of the fifth FET coupled through a resistor to the drain electrode of the second FET and to the drain electrode of a sixth FET with the sixth FET having its source electrode coupled to the source electrodes of the second and third FETs and the gate electrode for receiving a control signal of opposite polarity to the control signal applied to the gate electrode of the second FET. The switch is a series cell which provides linear switching of the input signal to an output over a wide range of frequencies. A shunt cell also incorporates diode clamping means as well as the additional diode and resistor to enable one to again accurately switch an input signal to an output terminal over a wide range of frequencies in an extremely linear manner and according to the first and second control signals of opposite polarity which are applied to respective FETs included in the shunt circuit.