In an example, a system includes an amplifier having an output stage configured to provide an output voltage, where the output stage includes a p-channel transistor and an n-channel transistor. The system includes a sense transistor having a gate coupled to a gate of the p-channel transistor, where the sense transistor is configured to sense a current of the p-channel transistor and produce a sense current. The system includes a current mirror coupled to the sense transistor and configured to provide the sense current to a gate of a control transistor, the control transistor having a source coupled to the gate of the p-channel transistor. The system includes a reference current source coupled to the control transistor and configured to provide a reference current. The control transistor is configured to adjust a gate current provided to the p-channel transistor based on comparing the sense current to the reference current.

This application relates to methods and apparatus for clipping prevention. A driver apparatus for driving a transducer has a switching driver configured to switch at least one output node between different switching voltages with a controlled duty-cycle to drive an output signal across the transducer. A clipping prevention controller is configured to control a gain applied to the input signal so as to provide limiting of the input signal to avoid clipping of the output signal. The clipping prevention controller is configured to dynamically control at least one limiting threshold used to determine when to apply limiting of the input signal based on an indication of load resistance of the transducer and the input voltage to the switching driver.

A push-pull radio frequency power amplifier includes a coupling feedback circuit, a drive stage circuit and a power output stage circuit, in which the coupling feedback circuit is connected with the drive stage circuit and/or the power output stage circuit; the coupling feedback circuit is configured to generate an alternating voltage at an input end of a first transistor and/or an input end of a push-pull transistor; when the alternating voltage and a voltage at the input end are in a same direction, a positive feedback of an input signal at the input end is achieved; and the first transistor represents a transistor in the drive stage circuit and the push-pull transistor represents a second transistor and a third transistor that form a push-pull structure in the power output stage circuit.