A FAST FOREGROUND DIGITAL CALIBRATION TECHNIQUE FOR PIPELINED ADC

Digital calibration techniques are widely developed to cancel the non-idealities of the pipelined Analog-to-Digital Converters (ADCs). This letter presents a fast foreground digital calibration technique based on the analysis of error sources which influence the resolution of pipelined ADCs. This method estimates the gain error of the ADC prototype quickly and calibrates the ADC simultaneously in the operation time. Finally, a 10 bit, 100 Ms/s pipelined ADC is implemented and calibrated. The simulation results show that the digital calibration technique has its efficiency with fewer operation cycles.

Optimization of Power Dissipation in Pipelined Analog-to-Digital Converter

Power optimization for pipelined analog-to-digital converter(ADC) was studied. Operational principle of pipelined ADC was discussed and noise voltage caused by two important thermal noise sources, sampling switch and amplifier,was quantitatively analyzed. Method used to minimize power and the values under simple model were presented. Power can be saved by making the sampling and feedback capacitors scale down in the pipeline.And the size of capacitors was limited by thermal noise in high resolution ADC.The equivalent circuits of the two important thermal noise sources were established.Thermal noise was optimally distributed among the pipeline stages,and the relationship between scaling factor and closed loop gain was obtained for minimum power dissipation.Typical closed loop gain was 2 or 4 in pipeline ADC, and the corresponding scaling factor was (1.217) and 1.317.These results can serve as useful guidelines for designers to minimize the ADC′s power consumption.

基于新型环形放大器的低功耗Pipelined SAR ADC

针对流水线型逐次逼近模数转换器(Pipelined SAR ADC)中残差放大器的核心运放功耗过高,从而严重限制ADC能效上限的问题,本文提出了一种新型的基于CMOS开关的自偏置全差分环形放大器(CMOS Self-biased Fully Differential Ring Amplifier,CSFRA),来替代传统运放。CSFRA通过引入CMOS开关自偏置和全差分结构,同时在非放大时序中关断电路,降低了残差放大器功耗。基于所提CSFRA,配合可降低开关功耗的检测和跳过切换方案,设计了一款12 Bit 10 MS/s的Pipelined SAR ADC。该电路基于MXIC L18B 180 nm CMOS工艺实现,实验结果表明,在10 MS/s的采样率下,该电路的SFDR和SNDR分别为75.3 dB和61.3 dB,功耗仅为944μW,其中CSFRA功耗仅为368μW。

A 4 Gbps current-mode transmitter for 12-bit 250 MSPS ADC

A 4 Gbps transmitter for a 12-bit 250 MSPS pipelined ADCs is presented.A low power current mode(CM) output driver with reverse scaling technique is proposed.A high speed,low power combined serializer is implemented to convert 12 bit parallel data into a serial data stream.The whole transmitter is used in a 12-bit250 MSPS pipelined ADC for the digital output buffer and fabricated in 180 nm 1.8 V 1P5M CMOS technology.Test results show that the transmitter provides an eye height greater than 800 mV for data rates of both 2 Gbps and 4 Gbps,the 12-bit 250 MSPS ADC achieves the SNR of 69.92 dBFS and SFDR of 81.17 dB with 20.1 MHz input at full sampling speed.The ADC with the 4 Gbps transmitter consumes the power consumption of 395 mW,where the power consumption of transmitter is 75 mW.The ADC occupies an area of 2.5×3.2 mm^2,where the active area of the transmitter block is 0.5×1.2 mm^2.