A current feed-back instrumentation amplifier (CFIA) comprises a differential pair with degeneration for amplifying small differential voltages in the presence of large common-mode voltages. The CFIA includes input and feedback transconductors and a trimming circuit that trims the back-bias voltages of the transistors in each transconductor. The trimming circuit includes a plurality of selectable resistors disposed in the signal path of the tail current in each transconductor. Each of the plurality of selectable resistors has a switch coupled to it. When a switch is closed, only the resistors up to the respective switch are in the signal path of the bulk-to-source voltage of the differentially paired transistors. The resistor trimming circuit reduces the mismatch between transconductances of the respective differential pair transistors, in turn reducing mismatch of the overall transconductances of the transconductors, and thereby reducing the CFIA's gain error.

An optical modulator driver circuit (1) includes an amplifier (50, Q10, Q11, R10-R13), and a current amount adjustment circuit (51) capable of adjusting a current amount of the amplifier (50) in accordance with a desired operation mode. The current amount adjustment circuit (51) includes at least two current sources (IS10) that are individually ON/OFF-controllable in accordance with a binary control signal representing the desired operation mode.

A circuit can include a first current source, a second current source, and a differential inverter amplifier electrically coupled between the first current source and the second current source. The differential inverter amplifier can include a plurality of load resistors and a plurality of diode-connected metal oxide semiconductor (MOS) clamps configured to limit output swing and minimize common mode disturbances.

A current feed-back instrumentation amplifier (CFIA) comprises a differential pair with degeneration for amplifying small differential voltages in the presence of large common-mode voltages. The CFIA includes input and feedback transconductors and a trimming circuit that trims the back-bias voltages of the transistors in each transconductor. The trimming circuit includes a plurality of selectable resistors disposed in the signal path of the tail current in each transconductor. Each of the plurality of selectable resistors has a switch coupled to it. When a switch is closed, only the resistors up to the respective switch are in the signal path of the bulk-to-source voltage of the differentially paired transistors. The resistor trimming circuit reduces the mismatch between transconductances of the respective differential pair transistors, in turn reducing mismatch of the overall transconductances of the transconductors, and thereby reducing the CFIA's gain error.

A current feed-back instrumentation amplifier (CFIA) comprises a differential pair with degeneration for amplifying small differential voltages in the presence of large common-mode voltages. The CFIA includes input and feedback transconductors and a chopping modulator circuit that continuously swaps tail current sources between the transconductors. This tail current swapping reduces the contribution to the CFIA's gain error caused by random mismatch between the tail currents of the input and feedback transconductors. The modulator circuit operates on a clock cycle to periodically swap the tail current sources. As a result, even if the tail currents are mismatched, on average the tail currents (transconductor gains) will approximately equal out, and the contribution of the tail current difference to the gain error is canceled out.

A traveling wave amplifier includes two input-side lines, two output-side lines, and amplification cells, and the amplification cells include a first input terminal, a second input terminal, a transistor including a base connected to the first input terminal and a collector connected to one of the output-side lines, a transistor including a base connected to the second input terminal and a collector connected to the other output-side line, a current source connected to an emitter of the two transistors, a series circuit having one end connected to the collector of the other transistor and the other end connected to the base of the one transistor and including a capacitor and a resistor, and a series circuit having one end connected to the collector of the one transistor and the other end connected to the base of the other transistor and including a capacitor and a resistor.

The disclosure provides an amplifier. The amplifier includes a first transistor that receives a first input. A second transistor receives a second input. A plurality of impedance networks is coupled between the first transistor and the second transistor. At least one impedance network of the plurality of impedance networks includes a first impedance path and a second impedance path. The first impedance path is activated during single ended operation, and the second impedance path is activated during differential operation.

A variable gain amplifier capable of stabilizing an average output potential of a differential output signal, improving power efficiency over a wide range of an amplitude of the differential input signal, and suppressing deterioration of a distortion rate is provided. The variable gain amplifier includes an amplifying circuit configured to amplify a differential input signal with a gain according to a gain control signal, and a current control circuit. The amplifying circuit has a first current source supplying a source current. The current control circuit adjusts a magnitude of the source current of the first current source according to a magnitude of the gain control signal.

A drive circuit for a serial communications system is provided. The drive circuit may include a mode controller, a pre-drive circuit, and a main drive circuit. The main drive circuit includes multiple mode control switches and at least one pair of differential switches. The mode controller is configured to: generate a mode control signal, and transmit the mode control signal to the main drive circuit. The pre-drive circuit is configured to: convert a differential digital signal into a differential control signal, and transmit the differential control signal to the main drive circuit. The main drive circuit controls on/off states of the multiple mode control switches according to the mode control signal, and works in corresponding working modes. The drive circuit controls the states of the mode control switches in the main drive circuit, so that the main drive circuit works in different working modes.

A semiconductor apparatus includes a receiver configured to generate an output signal by amplifying an input signal received through a channel, and compensate distortion of the input signal based on a control signal preset according to a voltage level of the input signal, and an internal circuit configured to operate in response to the output signal.