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.
This paper presents new architectures and implementations of original open-loop Class-BD audio amplifiers with balanced Common-Mode output. The output stage of each proposed amplifier includes the typical H-bridge with four MOSFETs and four additional MOSFET switches that balance and keep the Common-Mode output constant. The presented amplifiers employ the extended NBDD PWM or PSC PWM modulation scheme. When the output stage is built only on NMOSFET transistors, gate drivers require a floating power supply, using a self-boost charge pump with capacitive isolation of the control signal. The use of complementary MOSFETs in the output stage greatly simplifies gate control systems. The proposed amplifiers were compared to the typical Class-BD configuration, using the optimal NBDD modulation with respect to audio performance of the Differential-Mode (DM) and Common-Mode (CM) outputs. Basic SPICE simulations and experimental studies have shown that the proposed Class-BD amplifiers have similar audio performance to the prototype with the optimal NBDD modulation scheme, while at the same time having a balanced constant voltage CM output, thus eliminating the main contributor to radiation emission. As a result, the filtering of the DM output signals can be greatly simplified, while the filtering of the CM output signals can be theoretically eliminated. Practically, due to the timing errors added by the gate drivers, spikes are generated at the CM output, which are very easy to filter out by the reduced LC output filter, even at very low L.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.