advanced audio recording
pulse amplitude modulation - Class-D amplifier
  Cyclone II


sample rates



Audio DSP

This project shows the newest version of my Class-D amplifier circuit with an optimized modulation to reduce the load on the transistors and save thermal energy by combining pulse code modulation and pulse density modulation. It is totally realized with generic functions in VHDL.


Screen Shot of FPGA oscilloscope

PAM-PDM Class-D Amplifier

An internal FPGA-based oscilloscope is used to show the PDM-channels:
The green signal is the PCM-24bit from the input derived from S/PDIF.
A test signal with 5kHz + 15kHz is used to represent the high frequency behaviour.
The blue channels are the 4 digital output channels performing PDM.
The yellow channel is the digital output as it shows up in the analog electronic. It is resampled by a little ADC-module reading back the S/PDIF data.

 An Altera Cyclone II from Terasic is used to implement the graphical visualization of the synthesized audio via 4Bit-R2R-VGA.



© Dipl.-Ing. Jürgen Schuhmacher 2008