The signal to noise ratio （SNR） of conventional sigma delta analog to digital converter （∑△ADC） reduces with input signal strength. The existing concept of adaptive quantization is applied to the design of ∑△A...The signal to noise ratio （SNR） of conventional sigma delta analog to digital converter （∑△ADC） reduces with input signal strength. The existing concept of adaptive quantization is applied to the design of ∑△ADC to improve SNR with high dynamic range. An adaptive algorithm and its circuit implementation is proposed. Because of the error due to the circuit implementation, an error self-calibration circuit is also designed. Simulation results indicate that SNR can he nearly independent of the signal strength.展开更多
基于TSMC 65 nm 1.2 V CMOS工艺,设计了一款低功耗Sigma-Delta模数转换器(analog-to-digital converter, ADC)。调制器采用离散时间二阶前馈反馈型积分器级联(cascade of integrators with feed-forward and feedback, CIFFB)结构,其中...基于TSMC 65 nm 1.2 V CMOS工艺,设计了一款低功耗Sigma-Delta模数转换器(analog-to-digital converter, ADC)。调制器采用离散时间二阶前馈反馈型积分器级联(cascade of integrators with feed-forward and feedback, CIFFB)结构,其中第一级积分器创新性地结合了双采样技术与相关电平移位(correlated level shifting, CLS)技术,并采用两级浮动反向动态放大器(floating inverter amplifier, FIA)以降低功耗。数字滤波器采用三级CIC滤波器与五阶切比雪夫Ⅱ型IIR低通滤波器级联的结构,避免了传统结构中的CIC补偿滤波器和半带滤波器,减少了寄存器占用。仿真结果表明,该ADC在信号带宽为125 Hz、过采样率为512的条件下,信噪比达到108 dB,有效位数为17.65 bit,调制器功耗仅为5.5μW。展开更多
随着数字音源的普及,数模转换器(Digital to Analog Converter, DAC)成为音频设备中不可或缺的元件,其精度往往决定着整个系统的信号保真度。基于此,利用噪声整形技术对用于高精度音频DAC的Sigma-Delta调制器进行设计和现场可编程门阵列...随着数字音源的普及,数模转换器(Digital to Analog Converter, DAC)成为音频设备中不可或缺的元件,其精度往往决定着整个系统的信号保真度。基于此,利用噪声整形技术对用于高精度音频DAC的Sigma-Delta调制器进行设计和现场可编程门阵列(Field Programmable Gate Array, FPGA)实现。通过搭建测试系统,测试结果表明,所设计的Sigma-Delta调制器在输入信号为1 411.2 kHz采样频率、1 kHz频率、0 dBFS(Full Scale)幅度的正弦信号条件下,其输出信噪比(Signal to Noise Ratio, SNR)可达107.4 dB;当输入信号频率在音频频带内时(输入信号幅度为0dBFS),其输出SNR稳定保持在104 dB以上;并可用于WAV音乐播放器中。展开更多
文摘The signal to noise ratio （SNR） of conventional sigma delta analog to digital converter （∑△ADC） reduces with input signal strength. The existing concept of adaptive quantization is applied to the design of ∑△ADC to improve SNR with high dynamic range. An adaptive algorithm and its circuit implementation is proposed. Because of the error due to the circuit implementation, an error self-calibration circuit is also designed. Simulation results indicate that SNR can he nearly independent of the signal strength.
