用于RFID读写器的连续/离散混合级联ΣΔ调制器

Hybrid CT/DT Cascaded ΣΔ Modulator for RFID Reader

针对RFID读写器功耗受限、信号带宽大的特点,结合连续时间型和离散时间型ΣΔ调制器各自的优点,采用冲激不变法,将离散时间型ΣΔ调制器变换为连续时间型ΣΔ调制器,提出一种4位量化2-1连续/离散混合级联结构的ΣΔ调制器。该结构自带抗混叠特性,有效降低了调制器功耗,且对运放单位增益带宽要求低,适用于宽带领域。利用Simulink对其进行系统级建模和仿真,在过采样率为32、输入信号带宽为1.28MHz时,调制器的理想峰值信噪比达到103dB,即精度为16.87位。

Considering the characteristics of limited power consumption and large signal bandwidth for RFID readers, and taking advantages of continuous-time （CT） and discrete-time （DT） ∑△ modulators, a 2-1 hybrid CT/ DT cascaded ∑△ modulator with 4-bit quantization was proposed by transforming DT ∑△ modulator to CT ∑△ modulator using impulse-invariant transformation. This modulator not only provided inherent anti-alias feature, which helped to reduce power consumption effectively, but also had low unit gain bandwidth requirement for operational amplifier, making it suitable for broadband applications. System-level modeling and simulation were made on the modulator with Simulink. It has been shown that the modulator achieved an ideal peak SNR of 103 dB and a resolution of 16. 87 bits at an oversampling rate of 32 for an input signal bandwidth of 1.28 MHz.