A multi-stage amplifier with a high signal-to-noise ratio is introduced. Multiple amplification stages are cascaded between an input terminal and an output terminal of the amplifier. A controller switches the output stage among the multiple amplification stages from a normal mode to an attenuation mode in response to the amplifier input being lower than the threshold. In the attenuation mode, the output stage provides an attenuation resistor coupled in series with the load resistor of the amplifier. Noise is successfully attenuated by the attenuation-mode output stage.

An amplifier circuit including an input amplifier, an output amplifier and a diode device is provided. The output amplifier includes a PMOSFET and an NMOSFET. The PMOSFET has a gate electrode serving as a first input end and a drain coupled to an output end. The NMOSFET has a gate electrode serving as a second input end and a drain coupled to the output end. The output amplifier outputs an output voltage at the output end, and is coupled to the input amplifier via at least one of the first and second input ends. The diode device is coupled between the output end and the at least one of the first and second input ends of the output amplifier. When a voltage difference between the output end and the at least one of the first and second input ends of the output amplifier is greater than a barrier voltage of the diode device, the diode device is turned on, and an overshoot of the output voltage is reduced.

Transimpedance amplifiers with feedforward current are provided herein. In certain embodiments, an amplifier system includes a transimpedance amplifier that amplifies an input current received at an input to generate an output voltage at an output. The amplifier system further includes a controllable current source that is coupled to the output of the transimpedance amplifier, and operable to provide a feedforward current that changes in relation to the input current of the transimpedance amplifier. By providing a feedforward current in this manner, gain and speed performance of the transimpedance amplifier is enhanced.

A circuit for stabilizing a Class-D audio amplifier having a loop bandwidth modulator configured to modulate a loop bandwidth of the amplifier as a function of one or more control signals, a tuned output filter terminator coupled to a low-pass filter and configured to provide stabilizing control feedback to loop bandwidth modulator, and a carrier injection system configured to provide a wide range fixed frequency operation. Also, a method of stabilizing a feedback network within a Class-D amplifier by providing a first feedback loop coupling an output of a PWM logic stage of the amplifier to an input circuit of the amplifier, providing a second feedback loop coupling an output of a switching output stage of the amplifier to the input circuit, and providing a third feedback loop coupling an output of a low-pass filter of the amplifier to the input circuit.

An amplifier circuit including an input amplifier, an output amplifier and a diode device is provided. The output amplifier is coupled to the input amplifier and outputs an output voltage. The diode device is coupled between an output end and an input end of the output amplifier. When a voltage difference between the output end and the input end of the output amplifier is greater than a barrier voltage of the diode device, the diode device is turned on, and an overshoot of the output voltage is reduced.

An apparatus includes an amplifier, an input port, a first modulator circuit connected to the input port, and a correction circuit. The correction circuit is configured to determine a common mode voltage of the input port and receive a first clock signal. The correction circuit is further configured to manipulate, based at least in part upon the common mode voltage of the input port, the first clock signal to generate a second clock signal. The second clock signal is produced for the first modulator circuit. The correction circuit is further configured to determine whether the second clock signal is out of phase with a third clock signal, and, based upon a determination that the second clock signal is out of phase with the third clock signal, reset the second clock signal.

Transimpedance amplifiers with feedforward current are provided herein. In certain embodiments, an amplifier system includes a transimpedance amplifier that amplifies an input current received at an input to generate an output voltage at an output. The amplifier system further includes a controllable current source that is coupled to the output of the transimpedance amplifier, and operable to provide a feedforward current that changes in relation to the input current of the transimpedance amplifier. By providing a feedforward current in this manner, gain and speed performance of the transimpedance amplifier is enhanced.

An apparatus for controlling the gain and phase of an input signal input to a power amplifier comprises a gain control loop configured to control the gain of the input signal based on power levels of the input signal and an amplified signal output by the power amplifier, to obtain a predetermined gain of the amplified signal, and a phase control loop configured to obtain an error signal related to a phase difference between a first signal derived from the input and a second signal derived from the amplified signal, and control the phase based on the error signal, to obtain a predetermined phase of the amplified signal. The phase control loop delays the first signal such that the delayed first signal and the second signal used to obtain the error signal correspond to the same part of the input signal. The apparatus may be included in a satellite.

In an embodiment, A device includes an operational amplifier and a feedback loop. The feedback loop is coupled between a first input of the operational amplifier and an output of the operational amplifier. The feedback loop is controllable according to a saturation of the operational amplifier. In one example, the device is incorporated in a microcontroller.

Embodiments of an amplifiers and integrated circuits include a first transistor and a second transistor. A second current-carrying terminal of the first transistor may be coupled to a first current-carrying terminal of the second transistor and the control terminal of the second transistor may be coupled to a low impedance alternating current (AC) potential node. A bias network that includes a first circuit element and a second circuit element couples the second current-carrying terminal of the second transistor to the control terminal of the second transistor. The first circuit element may be configured to apply a portion of a potential at the second current-carrying terminal of the second transistor to the control terminal of the second transistor, and the second circuit element may be coupled between the control terminal of the second transistor and a fixed potential.