Analogue Sinusoidal Signal Generator Applied For BIST Of Mixed Signal ICs

This paper presents a digital sinusoidal source, based on the oversampling technique and the Delta-Sigma modulation(DSM) principle, that can produce high quality analog stimulus. With the exception of a low bits DAC and the post analog filter, the proposed circuit is entirely digital. The area of the proposed analog sinusoidal signal generator is low and thus it is suitable to be a built-in-self signal generator for mixed-signal IC testing.In this paper, we show a high Signal-to-Noise Ratio(SNR) second-order Delta-Sigma modulator in which the delay accumulator in traditional structure is replaced by Al-Alaoui integrator. The SNR expression of new structure is obtained through frequency domain analysis on noise transfer function and it shows the feature of controllable SNR. By learning experiences and methods from many other papers, we get the optimal coefficients of modulator through iteration using EDA tools. The experimental results reveal that its performance overcomes that of conventional one with lower quantization noise and 6.3% higher SNR.To realize the oversampling function, we cascaded 3 stage halfband filters and a CIC filter. The whole interpolation filter system achieves a 64X oversampling rate and has a perfect pass-band performance. We used multi-phase decomposition to simplified the structure and CSD coding technique also used to design half band filters.The design in this paper has been implemented and verified by Altera Stratix III series FPGA. The verification result shows the output of low bitstream can achieve 60.9dB when input is 16 bits digital sinusoidal wave.