FPGA-based Audio Digital to Analog Converter (DAC)

Specifications

  • Input : I2S, bitdepth from 16 to 32 bits, sampling rate upto 768khz,
  • Asynchronous FIFO built-in,
  • FPGA-based delta-sigma digital to analog converter (DAC),
  • 256-step digital volume,
  • Full balanced outputs,
  • Compatible with Raspberry Pi 3/3B+/4 connection,
  • Ultra-low phase noise oscillators with high precision linear low drop voltage regulators are designed specifically for High-Definition audio (HD audio).

Schematic and PCB design

Schematic and PCB were designed using Free open software KiCad

https://www.kicad.org/

Power supply for FPGA Cyclone IV

Oscillator block with 2 separated oscillators. Each one will provide clock for each sampling rate family (44.1 or 48)

3rd order Low pass filter

PCB layout with 4 layers

FPGA programming

(to be continued…)

FIFO Asynchronous I2S – Reclock

Features

  • Reduces jitter
  • Design includes FPGA based FIFO board
  • With 22.5792/24.576 MHz high precision Crystek’s Oscillator (Crystek CCHD-957 Series)
  • I2S input: 44.1 kHz, 48 kHz, 88.2 kHz, 96 kHz, 176.4 kHz, 192 kHz , 352.8kHz, 384kHz, 705.6kHz, 768kHz – 16bit, 24bit or 32bit
  • I2S output: 44.1 kHz, 48 kHz, 88.2 kHz, 96 kHz, 176.4 kHz, 192 kHz , 352.8kHz, 384kHz, 705.6kHz, 768kHz – 16bit, 24bit or 32bit
  • High speed double isolation (input isolation and output isolation)
  • Automatically switching frequencies according to the input I2S signals input
  • High precision and Ultra-low-noise voltage regulators