Certain aspects of the present disclosure provide methods and apparatus for amplifying signals with an amplification circuit. The amplification circuit generally includes a first transistor, an input path coupled between an input node of the amplification circuit and a control input of the first transistor, and a feedforward path coupled between the input node and a feedforward node. In certain aspects, the amplification circuit may also include a first resistive device coupled between the feedforward node and the control input of the first transistor, a biasing circuit coupled to the feedforward node, and a low-impedance path coupled to the feedforward node.

Certain aspects of the present disclosure provide methods and apparatus for amplifying signals with an amplification circuit. The amplification circuit generally includes a first transistor, an input path coupled between an input node of the amplification circuit and a control input of the first transistor, and a feedforward path coupled between the input node and a feedforward node. In certain aspects, the amplification circuit may also include a first resistive device coupled between the feedforward node and the control input of the first transistor, a biasing circuit coupled to the feedforward node, and a low-impedance path coupled to the feedforward node.

Design of ultra broadband transimpedance amplifiers (TIA) for optical fiber communications is disclosed. In one embodiment, a TIA comprises a g.sub.m-boosted dual-feedback common-base stage, a level shifter and an RC-degenerated common-emitter stage, and a first emitter-follower stage, wherein the first emitter follower stage is inductively degenerated. An output of the TIA is buffered using a second emitter-follower stage.

The present invention breaks up the frequency bands which can be filtered by a simple low-loss band-pass or low pass filter. The second harmonic frequency is reduced by use of a non-linear clipper element which controls the driving waveform symmetry and can reduce the harmonics by as much as 5-15 db which makes the filter much simpler and allows the amplifier to remain wide-band. The output waveform from the amplifier is symmetrical or nearly symmetrical.

An amplifier includes an output stage circuit and a compensation circuit. The output stage circuit includes a first input terminal, a second input terminal, a first output terminal, and a second output terminal. The compensation circuit includes a first capacitor, a second capacitor, a third capacitor, and a fourth capacitor. The first capacitor is coupled between the first input terminal and the second output terminal, and is configured to operate as a first Miller capacitor. The second capacitor is coupled between the second input terminal and the first output terminal, and is configured to operate as a second Miller capacitor. The third capacitor and the fourth capacitor are configured to alternately operate as the first Miller capacitor and the second Miller capacitor according to at least one clock signal.

A Doherty amplifier used in a Z ohm based system is provided with a carrier amplifier, a peak amplifier, and an impedance transforming line for transforming the load of the carrier amplifier when an input signal is small. The impedance transforming line has a characteristic impedance lower than Z ohms and equal to the optimum load impedance of the carrier amplifier. The load of the Doherty amplifier is lower than Z ohms. A power amplifier that obtains large output power by combining output powers from a plurality of Doherty amplifiers by a power coupling circuit is constructed.

A wide range differential current switching circuit can operate across a wide range of input currents and across a broad range of frequencies. A first differential current source can include a first transistor and a second transistor. The first transistor receives a switching signal and provides an output current and at output node. The second transistor receives an inverted switching signal, the first transistor and the second transistor coupled to each other at a tail node. A current source provides an input current to the tail node. A third transistor can provide a boost current to the tail node while the first transistor is off.

A wide range differential current switching circuit can operate across a wide range of input currents and across a broad range of frequencies. A first differential current source can include a first transistor and a second transistor. The first transistor receives a switching signal and provides an output current and at output node. The second transistor receives an inverted switching signal, the first transistor and the second transistor coupled to each other at a tail node. A current source provides an input current to the tail node. A third transistor can provide a boost current to the tail node while the first transistor is off.

The present invention is directed to electrical circuits. More specifically, an embodiment of the present invention provides a differential amplifier in cascode configuration. An input transistor is coupled to an output transistor via a peaking inductor. The output transistor is also directly coupled to a degeneration resistor. There are other embodiments as well.

The present invention is directed to electrical circuits. More specifically, an embodiment of the present invention provides a differential amplifier in cascode configuration. An input transistor is coupled to an output transistor via a peaking inductor. The output transistor is also directly coupled to a degeneration resistor. There are other embodiments as well.