An apparatus includes a differential amplifier. The differential amplifier includes a first side circuit configured to receive a first input signal, a second side circuit configured to receive a second input signal, and a resonant tank circuit coupled between the first and second side circuits. A first capacitor and first switch may be provided in series between a source and drain of a cascode transistor. A second capacitor and second switch may be provided in series between a source and drain of an input transistor. A method includes receiving a first input signal by a first side circuit, receiving a second input signal by a second side circuit, controlling a resource of a resonant tank circuit, and outputting an output signal according to the first and second input signals. The resource of the resonant tank circuit may be controlled according to a transmission mode, frequency band, or both.