A 78-MHz BW Continuous-Time Sigma-Delta ADC with Programmable VCO Quantizer  

作　　者：Sha Li Qiao Meng Irfan Tariq Xi Chen 

机构地区：[1]Institute of RF-&OE-ICs,Southeast University,Nanjing,210096,China [2]Jiangsu Key Construction Laboratory of IoT Application Technology,Wuxi Taihu University,Wuxi,214064,China [3]Polytechnic University of Madrid,Madrid,28031,Spain

出　　处：《Computers, Materials & Continua》2022年第9期6079-6090,共12页计算机、材料和连续体（英文）

基　　金：This work was supported by the Natural Science Foundation of the Jiangsu Higher Education Institutions of China under Grant No.18KJB510045.

摘　　要：This article presents a high speed third-order continuous-time(CT)sigma-delta analog-to-digital converter(SDADC)based on voltagecontrolled oscillator(VCO),featuring a digital programmable quantizer structure.To improve the overall performance,not only oversampling technique but also noise-shaping enhancing technique is used to suppress in-band noise.Due to the intrinsic first-order noise-shaping of the VCO quantizer,the proposed third-order SDADC can realize forth-order noise-shaping ideally.As a bright advantage,the proposed programmable VCO quantizer is digital-friendly,which can simplify the design process and improve antiinterference capability of the circuit.A 4-bit programmable VCO quantizer clocked at 2.5 GHz,which is proposed in a 40 nm complementary metaloxide semiconductor(CMOS)technology,consists of an analog VCO circuit and a digital programmable quantizer,achieving 50.7 dB signal-to-noise ratio(SNR)and 26.9 dB signal-to-noise-and-distortion ration(SNDR)for a 19 MHz−3.5 dBFS input signal in 78 MHz bandwidth(BW).The digital quantizer,which is programmed in the Verilog hardware description language(HDL),consists of two-stage D-flip-flop(DFF)based registers,XOR gates and an adder.The presented SDADC adopts the cascade of integrators with feed-forward summation(CIFF)structure with a third-order loop filter,operating at 2.5 GHz and showing behavioral simulation performance of 92.9 dB SNR over 78 MHz bandwidth.

关 键 词：Sigma-delta ADC oversampling converter VCO noise-shaping programmable quantizer 

分 类 号：TN761[电子电信—电路与系统]