A tunable bandpass filter comprising: a first autotransformer to provide impedance step-up at an input of the tunable bandpass filter; a second autotransformer to provide impedance step-down at an output of the tunable bandpass filter; two tuning portions, each said tuning portion comprising two or more switch legs connected in parallel to one another, each said switch leg comprising a GaAs FET switch and a first tuning capacitor; an inductive element, coupling the tuning portions together; and a control terminal to receive a control signal to turn the GaAs FET switch on or off; characterized in that: each switch leg further comprises a second tuning capacitor connected to ground, and a ground connection; said GaAs FET switch has a first signal terminal, a second signal terminal and a third signal terminal, and provides a low resistance conductive path between the first signal terminal and the second signal terminal when the GaAs FET switch is on, or provides a low resistance conductive path between the first signal terminal and the third signal terminal when the GaAs FET switch is off; the first tuning capacitor is connected to the first signal terminal of the GaAs FET switch, the second tuning capacitor is connected between the second signal terminal of the GaAs FET switch and ground, and the ground connection is connected to the third signal terminal of said GaAs FET switch. a first autotransformer to provide impedance step-up at an input of the tunable bandpass filter; a second autotransformer to provide impedance step-down at an output of the tunable bandpass filter; two tuning portions, each said tuning portion comprising two or more switch legs connected in parallel to one another, each said switch leg comprising a GaAs FET switch and a first tuning capacitor; an inductive element, coupling the tuning portions together; and a control terminal to receive a control signal to turn the GaAs FET switch on or off; characterized in that: each switch leg further comprises a second tuning capacitor connected to ground, and a ground connection; said GaAs FET switch has a first signal terminal, a second signal terminal and a third signal terminal, and provides a low resistance conductive path between the first signal terminal and the second signal terminal when the GaAs FET switch is on, or provides a low resistance conductive path between the first signal terminal and the third signal terminal when the GaAs FET switch is off; the first tuning capacitor is connected to the first signal terminal of the GaAs FET switch, the second tuning capacitor is connected between the second signal terminal of the GaAs FET switch and ground, and the ground connection is connected to the third signal terminal of said GaAs FET switch. each switch leg further comprises a second tuning capacitor connected to ground, and a ground connection; said GaAs FET switch has a first signal terminal, a second signal terminal and a third signal terminal, and provides a low resistance conductive path between the first signal terminal and the second signal terminal when the GaAs FET switch is on, or provides a low resistance conductive path between the first signal terminal and the third signal terminal when the GaAs FET switch is off; the first tuning capacitor is connected to the first signal terminal of the GaAs FET switch, the second tuning capacitor is connected between the second signal terminal of the GaAs FET switch and ground, and the ground connection is connected to the third signal terminal of said GaAs FET switch.