In conventional optical receivers the dynamic range is obtained by using variable gain amplifiers (VGA) with a fixed trans-impedance amplifier (TIA) gain. To overcome the SNR problems inherent in conventional receivers an improved optical receiver comprises an automatic gain control loop for generating at least one gain control signal for controlling gain of both the VGA and the TIA. Ideally, both the resistance and the gain of the TIA are controlled by a gain control signal.

According to a first aspect of the embodiments, a microphone mixer is provided comprising: an input adapted to receive differential microphone (mic) output signals; a gain-trim circuit adapted to receive the differential mic output signals, and which includes a substantially fully differential amplifier adapted to amplify the received differential mic output signals through use of a gain-trim output adjustment device that provides a variable gain amount ranging from a first gain-trim gain value to a second gain-trim gain value, to produce differential gain-trim circuit output signals; a fader circuit adapted to receive the differential gain-trim circuit output signals, and which includes a differential amplifier adapted to attenuate the received differential gain-trim circuit output signals through use of a fader output adjustment device that provides a variable gain amount ranging from a first fader gain value to a second fader value; and a common adjustment apparatus that mechanically ties the gain-trim output adjustment device with the fader output adjustment device such that the first gain-trim gain value and first fader gain value are obtained substantially simultaneously at a first position of the common adjustment apparatus, and the second gain-trim gain value and second fader gain value are obtained substantially simultaneously at a second position of the common adjustment apparatus.

In conventional optical receivers the dynamic range is obtained by using variable gain amplifiers (VGA) with a fixed trans-impedance amplifier (TIA) gain. To overcome the SNR problems inherent in conventional receivers an improved optical receiver comprises an automatic gain control loop for generating at least one gain control signal for controlling gain of both the VGA and the TIA. Ideally, both the resistance and the gain of the TIA are controlled by a gain control signal.

Disclosed is a differential transimpedance amplifier. The differential transimpedance amplifier includes a common gate amplifier configured to receive an electrical signal from an input node, and a common source amplifier configured to have a feedback resistor and receive the electrical signal form the input node. An output signal of the common gate amplifier and an output signal of the common source amplifier form a differential signal pair. The common gate amplifier and the common source amplifier each includes a load having a transformer which removes an effect of parasitic capacitance

The present disclosure describes a method and system for linearizing an amplifier using transistor-level dynamic feedback. The method and system enables nonlinear amplifiers to exhibit linear performance using one or more of gain control elements and phase shifters in the feedback path. The disclosed method and system may also allow an amplifier to act as a pre-distorter or a frequency/gain programmable amplifier.

Disclosed is a differential transimpedance amplifier. The differential transimpedance amplifier includes a common gate amplifier configured to receive an electrical signal from an input node, and a common source amplifier configured to have a feedback resistor and receive the electrical signal form the input node. An output signal of the common gate amplifier and an output signal of the common source amplifier form a differential signal pair. The common gate amplifier and the common source amplifier each includes a load having a transformer which removes an effect of parasitic capacitance.

Provided is an amplification circuit that amplifies an input signal and outputs an amplified signal. The amplification circuit includes: an amplification element that outputs the amplified signal from an output terminal thereof; an inductor having one end to which a power supply voltage is supplied and another end that is connected to the output terminal of the amplification element; a variable resistor that is connected in parallel with the inductor; and a resistance value adjusting circuit that adjusts a resistance value of the variable resistor in accordance with the temperature.

Hybrid variable gain amplifiers and methods of controlling hybrid VGAs are disclosed. The hybrid VGA includes a first portion that provides a current path between a positive input and a positive output, and a current path either between the positive input and a negative output, in a first mode of operation, or between the positive input and a voltage source, in a second mode of operation. A second portion of the VGA provides a current path between a negative input and the negative output, and a current path either between the negative input and the positive output, in the first mode of operation, or between the negative input and the voltage source, in the second mode of operation. Control voltages selectively enable the paths in the first or second mode of operation. The control voltages further control amount of current flow in the enabled paths.

Disclosed is a differential transimpedance amplifier. The differential transimpedance amplifier includes a common gate amplifier configured to receive an electrical signal from an input node, and a common source amplifier configured to have a feedback resistor and receive the electrical signal form the input node, wherein an output signal of the common gate amplifier and an output signal of the common source amplifier form a differential signal pair.

The present invention is directed to electrical circuits and techniques thereof. In various embodiments, the present invention provides a variable gain amplifier architecture that includes a continuous-time linear equalizer (CTLE) section and a variable gain amplifier (VGA) section. The CTLE section provides both a pair of equalized data signals and a common mode voltage. A DAC generates a control signal based on a control code. The VGA section amplifies the pair of equalized data signals by an amplification factor using a transistor whose resistance value is based on both the common mode voltage and the control signal. There are other embodiments as well.