一种新的带通Sigma-Delta调制器的设计

设计了一种带宽为1.25 MHz,中心频率为20 MHz的带通Sigma-Delta调制器,提出了一种新的结构及其系数的计算方法,该结构的性能受系数变化的影响较小,其谐振器的输出摆幅也较小,因而降低了对运算放大器的设计要求.模拟结果表明:考虑各种非理想因素后,调制器的动态范围(DR)为60 dB.

The Design of a New Band-Pass Sigma-Delta Modulator

Recently the Sigma-Delta modulator has been widely used in communication. One of the applications is to digitize the signal at intermediate frequency in a super-heterodyne receiver with a band-pass Sigma-Delta modulator. A band-pass Sigma-Delta modulator with a bandwidth at 1.25 MHz and a center frequency 20 MHz is designed, and a new modulator structure and its coefficient computing method are proposed. This structure is insensitive to coefficients variation, and its resonators' swing is low, thus lowering the requirement in the design of the operational amplifier. Simulation results indicate that the peak signal-noise-distortion-ratio of the modulator is 60 dB, and its dynamic range is 62 dB.