Sigma-delta Of The Dac Interpolation Filter Realization

The research and design of the interpolation filter used in Sigma-Delta Digital to Analog Converter (DAC) is introduced in the paper.In recent years, audio and video has entered the digital era, CD, DVD, MP3 and other digital electronic equipment become hot in the consumer electronics market. Meanwhile, along with VLSI technology, on one single chip integrated complexity of the digital signal processing capabilities has become possible, the study on the audio system DAC chip has great practical significance.The paper detailedly analysis the interpolation filter structure and the role based on the principle of Sigma-Delta DAC,and according to the Sigma-Delta Modulators, design the interpolation filter with 64 times oversampling rate. The interpolation filter is consisted of Halfband filter, 1/4 Lowpass filter and sample-hold circuit. The design begin from the system simulation, the three cascade structure is established, through the balance of the passband and stopband frequency, passband ripple, stopband attenuation and other parameters, greatly optimized the filter coefficients, the whole filter only use 67 coefficients, the area has been fully optimized. After the Verilog hardware description of the interpolation filter, FPGA verification thus ensure the hardware realization of the design. Finally, the synthesis, automatic placement and routing is doing to finish the final design.The chip has been manufactured using 0.18um CMOS mixed signal technology(3.3/1.8V voltage, double well, six layers of metal). Chip size is 1.389×1.452 um~2.Measured performance meets the design target, also the revisions is put forward according to the tested results.