Embodiments of the present invention provide a power amplifier, a radio remote unit RRU, and a base station. A multiphase pulse width modulator performs modulation to generate N multiphase pulse-width modulation PWM signals. The multiphase pulse-width modulation PWMn signal may be amplified. The multiphase pulse-width modulation PWMn signal may be filtered and a combination may be performed at a drain or a collector of a power amplifier transistor. According to the new radio frequency amplifier in accordance with the disclosure, envelope feeding loop inductance can be effectively reduced, so that video bandwidth is increased and DPD correction performance is improved.

A method and apparatus for decomposition of signals with varying envelope into offset components are disclosed here, that sample the time variant envelope of a single carrier (SC) or a multi-carrier (MC) band limited signal, quantizes the sampled value using N.sub.b quantization bits and decomposes the sample into N.sub.b in-phase and quadrature components that are combined in pairs and modulated to generate a set of N.sub.b offset signals. The pulse shape applied in each offset signal is selected according to the spectral mask needed for the signal and to minimize envelope fluctuations in each offset signal from the set of N.sub.b components.

An envelope tracking (ET) power amplifier apparatus is provided. The ET power amplifier apparatus includes a pair of power amplifiers configured to amplify a pair of radio frequency (RF) signals based on a pair of ET voltages. In one aspect, each of the RF signals is split before amplification and recombined after amplification. As such, the power amplifiers can operate based on half the peak power of the RF signals to help improve operating efficiency of the power amplifiers. In another aspect, the RF signals are pre-processed prior to amplification to form a pair of composite RF signals with similar average power such that the power amplifiers can operate based on substantially similar ET voltages. As a result, it may be possible to employ a single ET integrated circuit (ETIC) to provide the ET voltages, thus helping to reduce cost and footprint of the ET power amplifier apparatus.

Apparatus and methods for envelope tracking systems with automatic mode selection are provided herein. In certain configurations, a power amplifier system includes a power amplifier configured to provide amplification to a radio frequency signal and to receive power from a power amplifier supply voltage, and an envelope tracker including a signal bandwidth detection circuit configured to generate a detected bandwidth signal based on processing an envelope signal corresponding to an envelope of the radio frequency signal. The envelope tracker further includes a switch bank configured to receive a plurality of regulated voltages, a filter configured to filter an output of the switch bank to generate the power amplifier supply voltage, and a mode control circuit configured to control a filtering characteristic of the filter based on the detected bandwidth signal.

A power amplifier includes an in-phase modulator configured to modulate an in-phase component of an input signal, a quadrature modulator configured to modulate a quadrature component of the input signal, and a processor configured to process the in-phase and quadrature components. The processor includes a clock configured to produce a clock signal, a pulse processor configured to remove non-essential information from the modulated in-phase and quadrature components, and a pulse converter configured to select an amplifier class and output a control signal based on the selected amplifier class. A switching network is also included and configured to actuate one or more switches based on the control signal to output an amplified signal.

Embodiments described herein relate to an envelope tracking system that uses a single-bit digital signal to encode an analog envelope tracking control signal, or envelope tracking signal for brevity. In certain embodiments, the envelope tracking system can estimate or measure the amplitude of the baseband signal. The envelope tracking system can further estimate the amplitude of the envelope of the RF signal. The system can convert the amplitude of the envelope signal to a single-bit digital signal, typically at a higher, oversample rate. The single-bit digital signal can be transmitted in, for example, a low-voltage differential signaling (LVDS) format, from a transceiver to an envelope tracker. An analog-to-digital converter (ADC or A/D) can convert the single-bit digital signal back to an analog envelope signal. Moreover, a driver can increase the power of the A/D output envelope signal to produce an envelope-tracking supply voltage for a power amplifier.

Apparatus and methods for quadrature combined Doherty amplifiers are provided herein. In certain embodiments, a separator is used to separate a radio frequency (RF) input signal into a plurality of input signal components that are amplified by a pair of Doherty amplifiers operating in quadrature. Additionally, a combiner is used to combine a plurality of output signal components generated by the pair of Doherty amplifiers, thereby generating an RF output signal exhibiting quadrature balancing.

An RF receiver includes a low-noise amplifier (LNA) to receive and amplify RF signals, a transformer-based IQ generator circuit, one or more load resisters, one or more mixer circuit, and a downconverter. The transformer-based IQ generator is to generate a differential in-phase local oscillator (LOI) signal and a differential quadrature (LOQ) signal based on a local oscillator (LO) signal received from an LO. The load resisters are coupled to an output of the transformer-based IQ generator. Each of the load resisters is to couple one of the differential LOI and LOQ signals to a predetermined bias voltage. The mixers are coupled to the LNA and the transformer-based IQ generator to receive and mix the RF signals amplified by the LNA with the differential LOI and LOQ signals to generate an in-phase RF (RFI) signal and a quadrature RF (RFQ) signal. The downconverter is to down convert the RFI signal and the RFQ signal into IF signals.

Circuits and methods for reducing the cost and/or power consumption of a user terminal and/or the gateway of a telecommunications system that may include a telecommunications satellite. Embodiments include chained feedback-regulated voltage supply circuits. These circuits substantially eliminate the need for separate regulator circuits for each regulated voltage. These circuits are designed to automatically maintain a substantially constant first voltage at a first node for a first load and maintain a substantially constant second voltage at a second node for a second load. Some disclosed configurations of these circuits may be useful to achieve greater current capability at the same voltage without requiring larger switches and higher inductor and capacitor sizes that may be needed in a single (conventional) stage voltage supply circuit.

An electronic circuit including: a differential multiplier circuit with a first differential input and a second differential input and a differential output; and a phase locked loop (PLL) circuit including: (1) a balanced differential mixer circuit with a first differential input electrically connected to the differential output of the differential multiplier circuit, a second differential input, and an output; (2) a loop filter having an output and an input electrically connected to the output of the balanced differential mixer circuit; and (3) a voltage controlled oscillator (VCO) circuit having an input electrically connected to the output of the loop filter and with an output electrically feeding back to the second differential input of the balanced differential mixer circuit.