同步脉宽调制式高分辨力ADC研究

同步V/F转换器由于其输出频率的相位调制特性，以及输出频率上限的限制，影响了其分辨力的进一步提高。采用电荷平衡与双斜式原理相结合的同步V/F转换技术，可提高其分辨力。该文提出一种基于双比较器定电压的同步脉宽调制新技术，在定电压积分的基础上，通过较高的同步时钟脉冲自动“微调”积分时间，实现了一个周期内电荷的充分平衡。通过多周期测量，实现了各周期内电荷动态平衡调节效果。经实验验证和测试表明，分辨力达5位，最小二乘法拟合线性度优于0.005%。It is difficult to elevate resolution higher for Synchronous Voltage-to-Frequency Converter (SVFC) since its phase modulation characteristic and the restrict of output frequency upper limit. There are some approaches to elevate its resolution higher, for example, taking the technique of integrating charge balancing and slope voltage integral. In this paper, a novel principle and implementation technology based on synchronous Pulse-Width-Modulation (SPWM) mode via dual comparators for integral is brought forward. Its basic principle is charge balancing enough within one period via integral between two reference levels, and the integral time can be fine adjusted by higher frequency synchronous clock. Moreover, charge balancing can be dynamicly adjusted within gate time by multi-periods synchronous measurement method. Verifying test indicates that its resolution is better than 5 digits, and linearity referenced to Method of Least Square better than 0.005%.