Digital Power Amplification Techniques in Wireless Transmitters

Digital power amplification has emerged as a cornerstone in modern wireless transmitters, uniting high efficiency, linearity and spectral fidelity demanded by 5G and beyond. Unlike traditional analogue schemes, fully digital and hybrid architectures convert baseband signals into radio-frequency pulses via high-speed digital-to-analog converters or pulse-width modulators, followed by switching power amplifiers. Techniques such as polar modulation, outphasing and switched-capacitor power amplifiers harness digital signal processing to shape amplitude and phase trajectories, while advanced combining networks—Doherty, reconfigurable transformers and impedance-boosting structures—optimise efficiency across power back-off. Digital predistortion and hybrid finite-impulse-response filtering suppress nonlinearities and quantisation noise, ensuring stringent error vector magnitude and adjacent channel leakage specifications. The trend towards one-bit and time-mode modulation further reduces analogue complexity and enhances scalability for millimetre-wave applications. Collectively, these innovations yield compact, highly efficient transmitters that satisfy both the throughput and energy-saving imperatives of emerging wireless systems.

Research from Nature Portfolio

Recent studies have demonstrated a jitter-enhanced pulse-width modulation architecture that uniformly distributes controlled timing variations across RF cycles to elevate modulation resolution without raising switching frequency. By exploiting programmable jitter, the scheme achieves over 5-bit resolution improvement and error vector magnitude approaching –41 dB while operating at a reduced PWM clock of 400 MHz. This approach significantly lowers the requirements on switching power amplifiers, enabling more efficient all-digital RF transmitters that flexibly adapt to diverse baseband and carrier frequencies.

Digital Power Amplification Techniques in Wireless Transmitters publication trend

The graph below shows the total number of articles in digital power amplification techniques in wireless transmitters across all publications each year (not limited to Nature Index journals).

Technical terms

Pulse-Width Modulation (PWM): Encoding of amplitude information via duty-cycle variation of a fixed-frequency pulse train.

Error Vector Magnitude (EVM): Quantitative measure of modulation accuracy, indicating deviation between ideal and actual signal constellations.

Adjacent Channel Leakage Ratio (ACLR): Ratio of transmitted power in adjacent frequency bands to that in the assigned channel, reflecting spectral purity.

Power Added Efficiency (PAE): (P_out – P_in)/P_DC, a metric of amplifier efficiency considering input drive power.

Power Back-Off (PBO): Reduction in output power from saturation, expressed in decibels, at which efficiency is evaluated.

Digital Predistortion (DPD): Pre-processing technique that compensates for amplifier nonlinearities by shaping the input signal.

Doherty Power Amplifier: A two-stage combining architecture optimised for high efficiency at both peak and backed-off power levels.

Switched-Capacitor Power Amplifier (SCPA): A digital PA using capacitor switching networks to generate RF waveforms with high linearity.

Polar Modulation: Separation of amplitude and phase signals for independent digital processing to drive switching PAs.

References

1. An all-digital RF transmitter architecture based on jitter-enhanced PWM for flexible frequency applications. Scientific Reports (2025).
2. A Time-Mode-Modulation Digital Quadrature Power Amplifier Based on 1-bit Delta–Sigma Modulator and Hybrid FIR Filter. IEEE Journal of Solid-State Circuits (2024).
3. A CMOS Wideband Watt-Level 4096-QAM Digital Power Amplifier Using Reconfigurable Power-Combining Transformer. IEEE Journal of Solid-State Circuits (2022).
4. A Digital Power Amplifier With Built-In AM–PM Compensation and a Single-Transformer Output Network. IEEE Open Journal of the Solid-State Circuits Society (2023).