A balanced differential transimpedance amplifier with a single-ended input operational over a wide variation in the dynamic range of input signals. A threshold circuit is employed to either or a combination of (1) generate a varying decision threshold to ensure a proper slicing over a wide range of input current signal levels; and (2) generate a bias current and voltage applied to an input of a transimpedance stage to cancel out a dependence of the transimpedance stage voltage input on input current signal levels.

A differential amplifier comprises: a long tailed pair transistor configuration comprising a differential pair of transistors and a tail transistor; and a replica circuit configured to vary a feedback current in the replica circuit to match a replica voltage to a reference voltage, wherein varying the feedback current in the replica circuit 4 provides a bias voltage to the tail transistor in the long tailed pair which controls a tail current through the tail transistor to determine a common mode voltage in the long tailed pair.

An operational amplifier comprises: a first amplifier stage 4 comprising a first differential pair of transistors 8, 10 arranged to receive and amplify a differential input signal 18, 20 thereby providing a first differential output signal 22, 24; and a second amplifier stage 6 comprising a second differential pair of transistors 26, 28 arranged to receive and amplify the first differential output signal 22, 24 thereby providing a second differential output signal 38, 40.

A differential input amplification-stage circuit comprises a voltage unit, first and second bulk-driven transistors, first and second mirror current sources, and a differential amplifier unit. The first and the second bulk-driven transistors respectively receive first and second input voltages, and converts the first and the second input voltages into first and second output currents. The differential amplifier unit separately outputs first and second adjustment currents under an action of voltages output by the first to the third voltage output ends. The first and the second mirror current sources respectively output first and second predetermined currents according to the first output current and the first adjustment current, and the second output current and the second adjustment current, so as to maintain transconductance constancy of the differential input amplification-stage circuit. Therefore, output stability is improved.

An amplifier includes a first coil coupled to at least one input node. The amplifier further includes second and third coils. A first terminal of the second coil is coupled to a source terminal of a first transistor, while a second terminal of the second coil is coupled to a source terminal of a second transistor. A third coil includes first and second terminals coupled to gate terminals of the first and second transistors, respectively. Responsive to receiving an input signal, the first coil electromagnetically conveys the signal to the second and third coils.

Techniques for monitoring a distortion signal of a power amplifier circuit, where the output of a distortion monitoring circuit includes little or no fundamental signal and closely represents the actual distortion of the amplifier circuit of a wired communications system. The power amplifier circuit can generate a distortion feedback signal that does not affect the power amplifier's output power capability, e.g., no inherent loss in the fundamental output of the amplifier. That is, using a distortion monitor circuit, the power amplifier circuit can resolve a distortion feedback signal from the intended output signal of the output power amplifier circuit.

An amplifier includes a first coil coupled to at least one input node. The amplifier further includes second and third coils. A first terminal of the second coil is coupled to a source terminal of a first transistor, while a second terminal of the second coil is coupled to a source terminal of a second transistor. A third coil includes first and second terminals coupled to gate terminals of the first and second transistors, respectively. Responsive to receiving an input signal, the first coil electromagnetically conveys the signal to the second and third coils.

According to one embodiment, a differential power amplifier includes a pair of transistors, a transformer coupled to the drain terminals of the transistors, and an output transmission line. The differential power amplifier operates in a range of frequencies from a lower operating frequency to an upper operating frequency to provide a relatively linear gain between the lower operating frequency and the higher operating frequency. The drains of the transistors are coupled to the primary winding of the transformer. The output transmission line is coupled to the secondary winding of the transformer. The output transmission line further includes at least one inductor-capacitor (LC) circuit that is configured to match predetermined output impedance in view of the lower and upper operating frequencies of the differential power amplifier.

A differential pair gain stage is disclosed. In one embodiment, the gain stage includes a differential pair of depletion-mode transistors, including a first and a second n-type transistor. In certain embodiments of the invention, the depletion mode transistor may be GaN (gallium nitride) field effect transistors. The gain stage includes an active load including one or more depletion mode transistors electrically coupled to at least one of the drains of depletion mode transistors of the differential pair. The active load may include a source follower for maintaining the AC voltages at the drains of the differential pair at a constant value and may further include a casocde stage for setting a fixed drain source voltage across the output transistors to increase the output impedance and gain of the stage.

A differential input amplification-stage circuit comprises a voltage unit, first and second bulk-driven transistors, first and second mirror current sources, and a differential amplifier unit. The first and the second bulk-driven transistors respectively receive first and second input voltages, and converts the first and the second input voltages into first and second output currents. The differential amplifier unit separately outputs first and second adjustment currents under an action of voltages output by the first to the third voltage output ends. The first and the second mirror current sources respectively output first and second predetermined currents according to the first output current and the first adjustment current, and the second output current and the second adjustment current, so as to maintain transconductance constancy of the differential input amplification-stage circuit. Therefore, output stability is improved.