一种基于LPTV的开关电容模拟信息转换器设计

Design of switched capacitor analog-to-information converter based on LPTV

模拟信息转换器(analog-to-information converter,AIC)以低于Nyquist率的采样率成为下一代模拟数字转换器的核心技术。模拟信息转换器采用随机解调模块处理输入数据,系统存在典型的时变特性,从而导致理论模型与实际电路模型失配。针对该问题,以开关电容作为AIC的核心部件,利用线性周期时变(linear periodically time-variant,LPTV)理论将周期时变的AIC系统转换为线性时不变系统,推导其系统传输函数,从而建立了AIC理论模型的电路设计方法。实验证明,该电路设计方法使理论的系统传输函数与实际电路的系统传输函数很好的匹配,充分验证了该设计方案的有效性。重构结果表明该电路可以将采样速率降低到原有奈奎斯特率的25%,重构信号的信噪比最高可达39.7 dB。

Analog-to-information converter(AIC) become the next generation of the core technology of Analog to digital due to lower than the Nyquist sampling rate. AIC processes the input signal by random demodulator, thus the AIC system has typical time-varying characteristics which results in the mismatch between the theoretical model and the actual circuit model. Aiming at this problem, based on switched capacitor as the core component of AIC, using the linear periodically time-variant(LPTV) theory analysis periodic time-varying AIC system which is converted into a Linear Time invariant system, pushing the transmission function of the AIC system, the circuit design method of AIC theory model is established. Experimental results show that the circuit design method makes the theoretical system transfer function well-matched with the actual system transfer function, which fully verifies the effectiveness of the design scheme. The reconstitution result proves that the sampling rate of the system can be reduced to 25% of the original Nyquist rate using this circuit structure and the successfully reconstructed signal-to-noise ratio is up to 39.7 dB.