模数转换器(analog-to-digital converter,ADC)量化引入的信噪比(signal-to-noise ratio,SNR)损失是影响数字接收机性能的一个重要因素.根据ADC误差产生的机理,得到了关于量化位数和幅度因子(ADC最大量化电平与ADC输入电平的比值)的噪声表达式,求出了不同量化位数下的最佳幅度因子.针对存在干扰的情况,得出了ADC输出SNR关于输入SNR、量化位数和干信比的计算公式.计算结果表明,当要求输出SNR为-15 dB时,要实现30 dB、40 dB、50 dB和60 dB的抗干扰能力(量化损失小于1 dB)所需要的最小量化位数分别为5位、7位、9位和10位.%The loss of signal-to-noise ratio (SNR) due to analog-to-digital converter (ADC) is an important issue that impacts the performance of a digital receiver. According to the mechanism of ADC quantization error, a noise expression which depends both on the number of bits and on the amplitude factor (the ratio of the saturation level of the converter and the input level) is derived, and thus optimal amplitude factors are obtained under different numbers of bits. For the situation in the presence of interference, the output SNR is computed as a function of input SNR, number of bits as well as interference-to-noise ratio. Calculation results show that, when an output SNR of -15 dB is demanded, the quantization bits of 5, 7, 9 and 10 are minimally required to achieve 30 dB, 40 dB, 50 dB and 60 dB anti-jamming capability respectively (i.e. less than 1 dB SNR loss due to quantization).
展开▼
