Abstract: An impedance matching low noise amplifier (“LNA”) having a bypass switch includes an amplification circuit, a bypass switching network and a match adjustment circuit. The amplification circuit has an amplifier input and an amplifier output, and is configured to receive a radio frequency (RF) input signal at the amplifier input and apply a gain to generate an amplified RF output signal at the amplifier output. The bypass switching network is coupled to a low-gain control signal and is also coupled between the amplifier input and the amplifier output. The bypass switching network is configured to couple the amplifier input to the amplifier output when the low-gain control signal is enabled in order to feed the RF input signal through to the RF output signal. The match adjustment circuit is coupled to the low-gain control signal and the RF input signal, and is configured to couple the RF input signal to an impedance when the low-gain control signal is enabled.
Abstract: A high-efficiency amplifier (10, 18) that may be used in, for example, a radar system to amplify signals received at an exciter (22) before they are applied to an antenna (20). The amplifier includes, among other components, an adaptive matching network (48) that is controlled by a processing system (26) to allow the amplifier to be adaptively matched to the load as the operating frequency of the system undergoes changes. Specifically, the network is adjusted based upon information regarding the ratio R of reflected power over incident power measured at the load the last time the system operated at the same frequency. As a result, the system is able to respond more quickly to frequency changes.