Abstract: The present invention provides an amplifier unit including a carrier amplifier biased for Class A or Class AB operation; a peak amplifier biased for Class B or Class C operation, wherein an input signal is input to the carrier amplifier and the peak amplifier, and wherein output signals from the carrier amplifier and the peak amplifier are synthesized to output therefrom; a comparator configured to compare a gate bias voltage of a transistor device in the peak amplifier with a predetermined threshold voltage and output a first output signal; and a failure detection circuit configured to output a second output signal indicating presence or absence of failure, based on the first output signal received from the comparator.

Abstract: The present invention provides an amplifier unit including a carrier amplifier biased for Class A or Class AB operation; a peak amplifier biased for Class B or Class C operation, wherein an input signal is input to the carrier amplifier and the peak amplifier, and wherein output signals from the carrier amplifier and the peak amplifier are synthesized to output therefrom; a comparator configured to compare a gate bias voltage of a transistor device in the peak amplifier with a predetermined threshold voltage and output a first output signal; and a failure detection circuit configured to output a second output signal indicating presence or absence of failure, based on the first output signal received from the comparator.

Abstract: A feedforward amplifier having a distortion detection loop and a distortion elimination loop is provided that achieves increased accuracy, improved response, and stable operation. A variable attenuator is placed in front of a detector in a loop output stage, and the amount of attenuation in the variable attenuator is set large during a transient response period during the rising of the amplifier, and set small during a steady-state condition. The detection of the transition to the steady-state condition is accomplished, for example, by comparing the detector output with a prescribed threshold value. The width of perturbation is set large during a transient response period, and set small during a steady-state condition.

Abstract: Disclosed is a rotation signal detection device for use with a circuit for driving a DC motor with brushes, the device comprises a differential amplifier for detecting a pulse signal component of a waveform of the current supplied to the motor, a circuit for shaping an output of the differential amplifier, thereby actuating a logic circuit for controlling rotation of the motor by a DC level signal obtained from said shaped waveform.