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高精度D/A转换器的实际精度往往低于理论上的精度。针对这个长期困扰的难题,在设计16位D/A转换器的过程中,提出了一种熔丝修调技术,即通过修调电流源输出端的电流,有效地减小电流源失配和有限输出阻抗对D/A转换器的DNL和INL的影响,大幅度提高D/A转换器的精度。基于0.18μm CMOS工艺的测试结果表明:在采用熔丝修调技术前,该电路的DNL和INL分别为-0.72~9.07LSB和-5.55~18.1LSB;在采用熔丝修调技术后,该电路的DNL和INL分别为-3.95~0.70LSB和1.94~8.06LSB。当输入信号频率为102 MHz、采样频率为500MHz时,SFDR达到82.16dBc,完全满足D/A转换器高精度的要求。
The actual accuracy of a high-precision D / A converter is often lower than the theoretical accuracy. In response to this long-standing problem, a fuse trimming technique was proposed in the design of a 16-bit D / A converter. By trimming the current at the output of the current source, the current source mismatch and the limited The effect of the output impedance on the DNL and INL of the D / A converter greatly improves the accuracy of the D / A converter. The test results based on 0.18μm CMOS technology show that the DNL and INL of this circuit are -0.72 ~ 9.07LSB and -5.55 ~ 18.1LSB, respectively, before the fuse trimming technique is adopted. After adopting the fuse trimming technique, the circuit The DNL and INL were -3.95 ~ 0.70LSB and 1.94 ~ 8.06LSB, respectively. When the input signal frequency is 102 MHz and the sampling frequency is 500 MHz, the SFDR reaches 82.16 dBc, which fully meets the requirement of high precision of D / A converter.