Circuits including a low noise amplifier (LNA) configured to receive a radio-frequency (RF) that include an input transistor to receive a waveform control signal at a gate terminal are provided. The circuits include a control transistor configured to receive a gate signal from a source terminal in the input transistor when the waveform control signal is high and to discharge the gate signal into a current sink coupled to ground when the waveform control signal is low at a controlled rate based on a resistor-capacitor (RC) network and a changing gain of the control transistor. The circuits include a buffer and a dump transistor to connect the critical resistor for optimal damping to the input of LNA when the dump transistor is ‘on’ and disconnect when the dump transistor if off. Systems and methods for use in an NMR sensor including a circuit as above are also provided.