用fpga實現的DA轉換器，有說明和源碼，VDHL文件。
A PLD Based Delta-Sigma DAC
Delta-Sigma modulation is the simple, yet powerful,
technique responsible for the extraordinary
performance and low cost of today s audio CD
players. The simplest Delta-Sigma DAC consists of a
Delta-Sigma modulator and a one bit DAC. Since,
both of these components can be realized using
digital circuits, it is possible to implement a low
precision Delta-Sigma DAC using a PLD.
