A circuit for increasing an output direct-current level of a transimpedance amplification stage in a TIA (Trans-Impedance Amplifier) includes a transimpedance amplification stage, a differential amplification stage, a level boosting unit, and a DC-restore loop. An input terminal of the transimpedance amplification stage is used for inputting a photocurrent signal. An output terminal of the transimpedance amplification stage is directly connected to an input terminal of the differential amplification stage.

The present invention relates to a multi-stage and feed forward compensated complimentary current field effect transistor amplifiers, enabling a charge-based approach that takes advantage of the exponential properties incurred in sub-threshold operation. A plurality of complimentary pairs of novel current field effect transistors are connected in series to form a multi-stage amplifier.

A voltage regulator having a buffer circuit and method for operating the same is disclosed. A voltage regulator having a buffer circuit includes an input stage coupled to receive an input voltage and an output stage configured to provide an output signal on an output node. The output stage includes first and second output transistors coupled to the output node. The circuit further includes a buffer stage coupled between the input and output stages. The buffer stage includes a first buffer transistor having a gate terminal coupled to the input stage and a source terminal coupled to a gate terminal of the first output transistor. The circuit further includes a first current mirror coupled to the first buffer transistor, and a second current mirror coupled to the first current mirror, the second current mirror including the second output transistor.

An output stage circuit of an operational amplifier, the operational amplifier, and a signal amplifying method applied to the operational amplifier are provided. The output stage circuit includes an inverting circuit and a compensation module. The inverting circuit is electrically connected to a gain stage circuit of the operational amplifier. The inverting circuit generates an output signal of the operational amplifier. The compensation module includes a first compensation circuit, including a first current providing path and a first suppression activation circuit. The first current providing path provides a first compensation current. The first suppression activation circuit conducts the first compensation current to the inverting circuit if a first compensation condition related to a first gain stage signal generated by the gain stage circuit is satisfied. Variation of the output signal is suppressed because of the first compensation current.

A driver circuit is provided. The driver circuit includes a first operational amplifier circuit, a second operational amplifier circuit, and at least one power switching circuit is provided. The first operational amplifier circuit receives a first input signal and generates a first output signal according to the first input signal. The second operational amplifier circuit receives a second input signal and generates a second output signal according to the second input signal. The at least one power switching circuit is configured to be coupled to switch a first input stage circuit to one of a first output stage circuit and a second output stage circuit, and the at least one power switching circuit is further coupled to switch a second input stage circuit to the other one of the first output stage circuit and the second output stage circuit.

A power amplifier circuit includes lower-stage and upper-stage differential amplifying pairs, a combiner, first and second inductors, and first and second capacitors. First and second signals are input into the lower-stage differential amplifying pair. The upper-stage differential amplifying pair outputs first and second amplified signals. The combiner combines the first and second amplified signals. The lower-stage differential amplifying pair includes first and second transistors. A supply voltage is supplied to the collectors of the first and second transistors. The first and second signals are supplied to the bases of the first and second transistors. The upper-stage differential amplifying pair includes third and fourth transistors. A supply voltage is supplied to the collectors of the third and fourth transistors. The emitters of the third and fourth transistors are grounded via the first and second inductors and are connected to the first and second transistors via the first and second capacitors.

Disclosed herein are circuits, devices and methods that address challenges associated with power amplifier systems. A power amplifier system includes two or more fast error amplifiers coupled to corresponding power amplifiers. The fast error amplifiers are configured to generate envelope tracking signals based on a signal envelope, the envelope tracking signals modifying a DC-DC regulated voltage from a DC-DC converter to more efficiently operate the power amplifiers. By splitting the envelope tracking between two or more fast error amplifiers and amplification between corresponding two or more power amplifiers, the power, frequency or bandwidth, linearity, signal-to-noise ratio, efficiency, or the like of the power amplifier system can be improved. Wireless communications configurations with such power amplifier systems can provide uplink carrier aggregation and/or cellular signals based on standards and protocols that require increased bandwidth and/or power.

A common source preamplifier for a MEMS capacitive sensor is disclosed. The preamplifier is a single-stage amplifier employing negative feedback. The preamplifier provides stable gain independent of temperature and at the same time provides effective buffering for a subsequent stage. Further, the preamplifier may be configured to provide different values of gain. Furthermore, the preamplifier has lower noise and consumes lesser area and lesser power than prior art.

An optical receiver circuit is disclosed, including a photodiode, an output terminal, a first amplifier stage, and an electrostatic discharge (ESD) protection circuit. The photodiode may generate a receiver current based on received optical signals. The first amplifier stage may be coupled between the photodiode and the output terminal and include a first inductor coupled between the photodiode and an input of a first inverter, and a second inductor coupled between the input of the first inverter and a first resistor. The first resistor may be coupled between the second inductor and an output of the first inverter. ESD protection circuit may be coupled to the input of the first inverter. The output terminal may generate an output signal based at least in part on the output of the first inverter.

An optical receiver includes a transimpedance amplifier that converts a current signal corresponding to an optical signal into a voltage signal. The transimpedance amplifier includes an input terminal receiving the current signal, an output terminal outputting the voltage signal, an inverting circuit including a pull-up device that pull-up drives the voltage signal of the output terminal according to the current signal, and a pull-down device that pull-down drives the voltage signal of the output terminal according to the current signal, a feedback resistor electrically connected between the input and output terminals, a first resistor electrically connected between the input terminal and the pull-up device, and a second resistor electrically connected between the input terminal and the pull-down device.