An amplifier includes a semiconductor substrate. A first conductive feature partially covers the bottom substrate surface to define a conductor-less region of the bottom substrate surface. A first current conducting terminal of a transistor is electrically coupled to the first conductive feature. Second and third conductive features may be coupled to other regions of the bottom substrate surface. A first filter circuit includes an inductor formed over a portion of the top substrate surface that is directly opposite the conductor-less region. The first filter circuit may be electrically coupled between a second current conducting terminal of the transistor and the second conductive feature. A second filter circuit may be electrically coupled between a control terminal of the transistor and the third conductive feature. Conductive leads may be coupled to the second and third conductive features, or the second and third conductive features may be coupled to a printed circuit board.

Multi-band power amplification system having enhanced efficiency through elimination of band selection switch. In some embodiments, a power amplification system can include a plurality of power amplifiers (PAs), with each PA being configured to receive and amplify a radio-frequency (RF) signal in a frequency band. The power amplification system can further include an output filter coupled to each of the PAs by a separate output path such that the power amplification system is substantially free of a band selection switch between the plurality of PAs and their corresponding output filters. Each PA can be further configured to drive approximately a characteristic load impedance of the corresponding output filter by, for example, the PA being operated with a high-voltage (HV) supply.

A non-isolated power supply. A positive power and a negative power are respectively formed by charging a +VCC1 energy storage filter and a ?VCC2 energy storage filter connected in series and discharging the +VCC1 energy storage filter 102 and the ?VCC2 energy storage filter. The output positive and negative power may be differently combined by changing the capacities of the +VCC1 energy storage filter and the ?VCC2 energy storage filter and may be equal or unequal.

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 multi-band power amplifier module includes at least one transmission input terminal, at least one power amplifier circuit that receives a first transmission signal and a second transmission signal through the at least one transmission input terminal, a first filter circuit that allows the first transmission signal to pass therethrough, a second filter circuit that allows the second transmission signal to pass therethrough, at least one transmission output terminal through which the first and second transmission signals output from the first and second filter circuits are output, a transmission output switch that outputs each of the first and second transmission signals output from the at least one power amplifier circuit to the first filter circuit or the second filter circuit, and a first tuning circuit that adjusts impedance matching between the at least one power amplifier circuit and the at least one transmission output terminal.

A circuit includes an amplifier configured to amplify an input signal and generate an output signal. The circuit also includes a tuning network configured to tune frequency response of the amplifier. The tuning network includes at least one tunable capacitor, where the at least one tunable capacitor includes at least one micro-electro mechanical system (MEMS) capacitor. The amplifier could include a first die, the at least one MEMS capacitor could include a second die, and the first die and the second die could be integrated in a single package. The at least one MEMS capacitor could include a MEMS superstructure disposed over a control structure, where the control structure is configured to control the MEMS superstructure and tune the capacitance of the at least one MEMS capacitor.

The present technology relates to an amplifier, an audio signal output method, and an electronic device that can inhibit unintended sound output in a class D amplifier that changes a peak value of a PWM signal. The amplifier includes: a positive-side amplitude generating circuit configured to generate positive-side amplitude of an output PWM signal that is a PWM signal to be output outside an apparatus; a negative-side amplitude generating circuit configured to generate negative-side amplitude of the output PWM signal; and a feedback circuit configured to feed back a difference between the amplitude generated by the positive-side amplitude generating circuit and the amplitude generated by the negative-side amplitude generating circuit to the positive-side amplitude generating circuit and the negative-side amplitude generating circuit. The present technology is applicable, for example, to an amplifier or the like of an electronic device such as an audio player.

Examples disclosed herein relate to a Doherty Power Amplifier (DPA) with integrated second harmonic injection. The DPA includes an amplifier circuit having a carrier amplifier and a peaking amplifier, and a combiner network coupled to the amplifier circuit, the combiner network having a plurality of transmission lines and a LC resonant circuit to inject a second harmonic from the carrier amplifier into the peaking amplifier.

Reduced power amplifier size through elimination of matching network. In some embodiments, a power amplification system can include a power amplifier (PA) configured to receive and amplify a radio-frequency (RF) signal. The power amplification system can further include a filter coupled to the PA and configured to condition the amplified RF signal. The PA can be further configured to drive approximately a characteristic load impedance of the filter. Such a configuration of the PA can be achieved by operating the PA with a high-voltage supply. Such a power amplification system can allow elimination of a matching network to, for example, reduce loss and device size.

In a digital transmitter, a digital RF signal generation unit executes digital modulation on I and Q signals to convert the I and Q signal into first and second digital RF signals , respectively, with a bit rate which is twice a carrier frequency. A retiming unit delays the first digital RF signal according to a clock signal with a frequency which is 4n times (n is an integer) the carrier frequency to output the delayed first digital RF signal and delays the phase of the second digital RF signal by 90 degrees with respect to an output of the first digital RF signal to output the delayed second digital RF signal. First and second amplifiers amplify the first and second digital RF signals output by the retiming unit, respectively. A combiner combines the amplified first and second digital RF signals to generate one signal sequence.