Modulation and System Techniques in PWM and SDM Switching Amplifiers
Continuous- and discrete-time switching audio power amplifiers are studied both with and without feedback. Pulse-width modulation (PWM) and sigma–delta modulation (SDM) amplifier configurations are simulated and their interrelationship is described using linear phase modulation (LPM) and linear frequency modulation (LFM). Distortion generation encountered when applying negative feedback to PWM is demonstrated and strategies to improve linearity are presented. Recent innovations in SDM coding and output-stage topologies using pulse-shaping techniques are reviewed with emphasis on stable, low-distortion operation, especially under high-level signal excitation. A simplified low-latency variant of predictive SDM with step back is introduced, which together with dynamic compression of the state variables extends stable operation to a modulation depth of unity, thus allowing SDM to compete with PWM power amplifiers in terms of peak signal capability.
Click to purchase paper or login as an AES member. If your company or school subscribes to the E-Library then switch to the institutional version. If you are not an AES member and would like to subscribe to the E-Library then Join the AES!
This paper costs $20 for non-members, $5 for AES members and is free for E-Library subscribers.