An apparatus comprising: a low-noise amplifier (202, 304) comprising a cascode amplifier (M1, M2) for receiving RF signals in a wireless receiver configured to amplify an input signal to produce an amplified signal at an amplifier output terminal, wherein the low-noise amplifier comprises a transformer for coupling the cascode amplifier to the amplifier output terminal; a transmission line connected between the amplifier output terminal and a switchable gain buffer (203, 308) to produce a gain buffer input signal at a switchable gain buffer input, the switchable gain buffer comprising a plurality of selectable gain channels that are configured to provide constant input impedance to match to the transmission line impedance at the switchable gain buffer input and to receive the switchable gain buffer input signal and generate an output signal at an output terminal having at least one of selected gain and current characteristics by selecting one selectable gain channel of the plurality of selectable gain channels, wherein the output of each gain channel is coupled to the output terminal, wherein the plurality of selectable gain channels utilize transistors having different transconductance values, and wherein each selectable gain channel of the plurality of selectable gain channels comprises two transistors in series having a common-gate stage configuration, with the different common-gate stages having different transistor device sizes, the switchable gain buffer configured to produce the output signal in response to the gain buffer input signal and a gain of a selected gain channel of the plurality of selectable gain channels; and wherein, one or more of the gain channels comprises an impedance network configured based on the size of a corresponding transistor in the one or more gain channels to produce the constant matching input impedance to match to the impedance of the transmission line, the impedance network comprising a resistor. a low-noise amplifier (202, 304) comprising a cascode amplifier (M1, M2) for receiving RF signals in a wireless receiver configured to amplify an input signal to produce an amplified signal at an amplifier output terminal, wherein the low-noise amplifier comprises a transformer for coupling the cascode amplifier to the amplifier output terminal; a transmission line connected between the amplifier output terminal and a switchable gain buffer (203, 308) to produce a gain buffer input signal at a switchable gain buffer input, the switchable gain buffer comprising a plurality of selectable gain channels that are configured to provide constant input impedance to match to the transmission line impedance at the switchable gain buffer input and to receive the switchable gain buffer input signal and generate an output signal at an output terminal having at least one of selected gain and current characteristics by selecting one selectable gain channel of the plurality of selectable gain channels, wherein the output of each gain channel is coupled to the output terminal, wherein the plurality of selectable gain channels utilize transistors having different transconductance values, and a plurality of selectable gain channels that are configured to provide constant input impedance to match to the transmission line impedance at the switchable gain buffer input and to receive the switchable gain buffer input signal and generate an output signal at an output terminal having at least one of selected gain and current characteristics by selecting one selectable gain channel of the plurality of selectable gain channels, wherein the output of each gain channel is coupled to the output terminal, wherein the plurality of selectable gain channels utilize transistors having different transconductance values, and wherein each selectable gain channel of the plurality of selectable gain channels comprises two transistors in series having a common-gate stage configuration, with the different common-gate stages having different transistor device sizes, the switchable gain buffer configured to produce the output signal in response to the gain buffer input signal and a gain of a selected gain channel of the plurality of selectable gain channels; and wherein, one or more of the gain channels comprises an impedance network configured based on the size of a corresponding transistor in the one or more gain channels to produce the constant matching input impedance to match to the impedance of the transmission line, the impedance network comprising a resistor.