Abstract:

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).