Methods and systems for vector combining power amplification are disclosed herein. In one embodiment, a plurality of signals are individually amplified, then summed to form a desired time-varying complex envelope signal. Phase and/or frequency characteristics of one or more of the signals are controlled to provide the desired phase, frequency, and/or amplitude characteristics of the desired time-varying complex envelope signal. In another embodiment, a time-varying complex envelope signal is decomposed into a plurality of constant envelope constituent signals. The constituent signals are amplified equally or substantially equally, and then summed to construct an amplified version of the original time-varying envelope signal. Embodiments also perform frequency up-conversion.

The present application relates to a digital modulator comprising an output stage comprising a number of unit cell arrays, and a sampling stage. The present application relates also to a communication device comprising said digital modulator, a method for digitally modulating and a computer program product. More particularly, the digital modulator comprises an output stage comprising a number of unit cell arrays, wherein the output stage comprises at least one carrier frequency signal input terminal configured to receive a carrier frequency signal. The digital modulator comprises a sampling stage connectable to the output stage, wherein the sampling stage is configured to oversample at least one data input signal. The digital modulator comprises at least one sampling clock generating device configured to generate at least one sampling clock signal depending on the number of arranged unit cell arrays and the carrier frequency signal.

A transmitter arrangement includes a first and a second phase-locked loop (1, 2), each having a power amplifier (PA1, PA2). The first phase-locked loop (1) generates a first amplified oscillator signal depending on a first input signal representing a first phase information, wherein a first feedback signal for the first phase-locked loop (1) is derived from the first amplified oscillator signal. Accordingly, the second phase-locked loop (2) generates a second amplified oscillator signal depending on a second input signal representing a second phase information. A second feedback signal for the second phase-locked loop (2) is derived from the second amplified oscillator signal. The transmitter arrangement further includes a summation element (SU1) to combine the amplified first oscillator signal and the amplified second oscillator signal to an output signal.

Digital transmitters having improved characteristics are described. In one design of a digital transmitter, a first circuit block receives inphase and quadrature signals, performs conversion from Cartesian to polar coordinates, and generates magnitude and phase signals. A second circuit block (which may include a delta-sigma modulator or a digital filter) generates an envelope signal based on the magnitude signal. A third circuit block generates a phase modulated signal based on the phase signal. The third circuit block may include a phase modulating phase locked loop (PLL), a voltage controlled oscillator (VCO), a saturating buffer, and so on. A fourth circuit block (which may include one or more exclusive-OR gates or an amplifier with multiple gain states) generates a digitally modulated signal based on the envelope signal and the phase modulated signal. A fifth circuit block (which may include a class D amplifier and/or a power amplifier) amplifies the digitally modulated signal and generates an RF output signal.