A multi-mode multi-band power amplifier includes a controller, a wide-band amplifier channel and a fundamental impedance transformer. The controller receives an external signal and outputs a control signal according to the external signal. The wide-band amplifier channel receives single-band or multi-band RF signals through the input terminal, performs power amplification on the RF signals and outputs the RF signals through the output terminal. The fundamental impedance transformer includes a first segment shared by RF signals in all bands, second segments respectively special for RF signals in all bands, and a switching circuit controlled by the controller to separate RF signals subject to power amplification to the second segment in a switchable manner for multiplexed outputs.

A reconfigurable load modulation amplifier having a first power amplifier (PA) configured to be supplied by a first drain voltage and a second PA coupled in parallel with the first PA, wherein the second PA is configured to be supplied by a second drain voltage is disclosed. The reconfigurable load modulation amplifier includes a quadrature coupler configured to combine power from both the first PA and the second PA for output through an output port. Also included is control circuitry configured to set at least one of the first drain voltage and the second drain voltage such that the first drain voltage is different than the second drain voltage. In at least one embodiment, the control circuitry is further configured to dynamically adjust at least one of the first drain voltage and the second drain voltage such that the first drain voltage is different than the second drain voltage.

A parallel input and dynamic cascaded OTA (operational transconductance amplifier includes: plural sub-OTAs which generate corresponding plural transconductance output currents according to corresponding plural differential input voltages; and at least one cascading capacitor which is cascaded between a first sub-OTA and a second sub-OTA. A second transconductance output current generated by the second sub-OTA is coupled through the cascading capacitor to generate a transient bias current on a common mode bias node of the first sub-OTA, thus providing the transient bias current to a differential pair circuit of the first sub-OTA in a case when a transient variation occurs in the differential input voltage corresponding to the first sub-OTA, so that a loop bandwidth and a response speed during a transient state are enhanced.

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.

A circuit for amplifying a source signal generated by a signal source having a first impedance includes a transmission line transformer (TLT) having a first, a second, a third, and a fourth port wherein the TLT is coupled to receive the source signal at the first port and configured to output a corresponding impedance matched signal at the second port, the second port is coupled to the third port of the TLT, the circuit also including a TLT load having a first terminal coupled to the fourth port of the TLT and a second terminal coupled to a reference potential. The circuit additionally includes an amplifier device responsive to the impedance matched signal to generate an amplified signal.

An amplifier circuit comprises a variable degeneration circuit connected to emitter terminals of transistors, and a variable negative capacitance circuit connected to differential output signal terminals. The variable degeneration circuit includes a variable capacitor and a resistor. The variable negative capacitance circuit, which is a variable current source, includes a transistor, a capacitor, and a variable current source. The variable negative capacitance circuit includes transistors, a capacitor, and variable current sources.

A multi-stage amplifier, comprising a first amplifier stage is presented. The output of the first amplifier stage is coupled to a first terminal of a capacitor having a controllable capacitance. The input of a second amplifier stage is coupled to the output of the first amplifier stage and the first terminal of the capacitor. The output of the second amplifier stage is coupled to a second terminal of the capacitor and an output of the multi-stage amplifier. The input of a current sensing circuit is coupled with the output of the multi-stage amplifier. A control signal generator is coupled between the output of the current sensing circuit and a control terminal of the capacitor. The control signal generator provides a control signal to the capacitor in order to control or vary the capacitance of the capacitor.

A reconfigurable load modulation amplifier having a carrier amplifier and a peak amplifier that are coupled in parallel is disclosed. The peak amplifier provides additional power amplification when the carrier amplifier is driven into saturation. A quadrature coupler coupled between the carrier amplifier and the peak amplifier is configured to combine power from both the carrier amplifier and the peak amplifier for output through an output load terminal. The reconfigurable load modulation amplifier further includes control circuitry coupled to an isolation port of the quadrature coupler and configured to provide adjustable impedance at the isolation port of the quadrature coupler. As such, impedance at the isolation port of the quadrature coupler is tunable such that at least a carrier or peak amplifier is presented with a quadrature coupler load impedance that ranges from around about half an output load termination impedance to around about twice the output load termination impedance.

A power amplifier gain switching circuit includes: a gain controller configured to receive an external input signal, output a first input signal, receive an external drive signal, and output a control signal based on the drive signal; an amplifier including: a bias input terminal configured to receive an external bias voltage; a signal input terminal configured to receive the first input signal; a control terminal configured to receive the control signal; and an output terminal configured to output an output signal with a gain; wherein the amplifier is configured to switch a gain factor of the output signal based on the control signal.

The invention describes a broadband matching network for coupling to an output of an amplifying device for amplifiers with a nominal operating frequency between 1 MHz and 100 MHz. The broadband matching network comprises a planar transformer with a primary winding arranged on a primary side of the broadband matching network and a secondary winding arranged on a secondary side of the broadband matching network. The primary winding is arranged to be electrically connected to the output of the amplifying device. The broadband matching network is characterized by a center frequency and a bandwidth with a frequency range of at least +/3%. A first parallel resonance frequency and a second parallel resonance frequency of the broadband matching circuit are arranged around the series resonance frequency such that a frequency dependence of a load impedance provided by the broadband matching network for the amplifying device is reduced.