Hybrid LBDD PWM modulator for digital class-BD audio amplifier based on STM32F407VGT6 microcontroller and analog DLL

Abstract

In the paper a new architecture and implementation of the 9-bit hybrid LBDD PWM modulator for digital Class-BD audio amplifier has been proposed. First, the PCM audio signal is transformed into the requantized to 9-bit resolution DPWM data, using LBDD algorithm. Then the 9-bit DPWM data are converted into the two physical trains of PWM pulses to control the output power transistors, using two hybrid digital to time converters (HDTC). The HDTC converts 6 MSB data on the base counter method using advanced-control timers TIM1 and TIM8 of the STM32F407VGT6 microcontroller, while the remaining 4 LSB data - using a quantizer system based on the tapped voltage controlled delay line (TVCDL) put into the ADLL loop, which have been designed in 180nm CMOS technology from UMC. A basic feasibility study of proposed configuration has been performed.