Charge Sampling Circuits and A/D Converters  Theory and Experiments
(2004) Abstract
 The analysis of general charge sampling technique is presented in this thesis. Charge sampling integrates input current instead of tracking input voltage to realize high speed and low voltage sampling. The analysis focuses on the performance of general charge sampling circuits for signal capture. The theoretical analysis here can be applied not only for the weak signal capture, but also for the normal signal sampling. Based on a general charge sampling model, the transfer function, the noise performance and the clock jitter tolerance are analyzed and compared to conventional voltage sampling. The results provide a theoretical basis for the charge sampling circuit design. The extended work for an accurate sampleandhold circuit model with... (More)
 The analysis of general charge sampling technique is presented in this thesis. Charge sampling integrates input current instead of tracking input voltage to realize high speed and low voltage sampling. The analysis focuses on the performance of general charge sampling circuits for signal capture. The theoretical analysis here can be applied not only for the weak signal capture, but also for the normal signal sampling. Based on a general charge sampling model, the transfer function, the noise performance and the clock jitter tolerance are analyzed and compared to conventional voltage sampling. The results provide a theoretical basis for the charge sampling circuit design. The extended work for an accurate sampleandhold circuit model with a finite sampling duration is also presented. The results provide a better theoretical basis for understanding and designing a sampleandhold circuit with finite tracking time, especially when considering the RF sampling (or subsampling) and kT/C noise.
A CMOS 6switch charge sampler is developed based on the charge sampling principle. With dummy capacitors operating alternatively in positive and negative branches, the resetting phase is embedded in the charging phase. The speed of the sampling is improved. A 500 MS/s charge sampling circuit was implemented in a 0.25 $mu$m CMOS process and measured. The dynamic range reaches 42 dB within the 250 MHz bandwidth. The power consumption is about 5 mW.
Based on the principle of charge sampling, a novel charging FIR filters was suggested and implemented. The proposed FIR filter functions by summing the weighted current signal on a passive capacitor. First, the input signal is weighted by a resistor ladder, whose resistance is decided by the impulse response of the FIR filter. A linear transconductor then converts the weighted voltage to current and charges the capacitor linearly. The hardware cost is not proportional to the tap number in the proposed FIR filter. Two 32tap filter prototypes were implemented in the AMS 0.35 $mu$m CMOS process. For the first filter, the measured sideband attenuation reaches 60 dB. The group delay is lower than 11 ns. The power consumption is about 35 mW under 3.3 V supply voltage. For the second one, the measured sideband attenuation is about 40 dB. The group delay is about 50 ns. The power consumption is about 7 mW under 2 V supply voltage.
A differential difference comparator (DDC) is proposed for A/D conversion. The proposed DDC provides easy linear voltage subtraction and comparison functions via current operation. Since there are no feedback loops, the speed of the analog signal subtraction is inherently faster when being used in an analogtodigital converter. Based the DDC, a CMOS pingpang mode 200 MS/s 8 bit 2step subranging A/D converter was implemented in the AMS 0.35 $mu$m CMOS process. Because of mismatch, the measured DNL for one branch is about 1.5 LSB and INL is about 2.2 LSB at 100 MS/s. The measured spurious free dynamic range at 100 MS/s (one branch) is 51 dB with 50 kHz sine input, while 39.2 dB at 200 MS/s (two branches) with 600 kHz signal input. The power consumption is 170 mW at 200 MS/s.
Some other results on the A/D converters, such as an 80 dB sigmadelta modulator and a programmable A/D converter, are also included in the thesis. These works focus on the feasibility and flexibility study of the sigmadelta and pipelined A/D converters. (Less)
Please use this url to cite or link to this publication:
http://lup.lub.lu.se/record/21795
 author
 Xu, Gang ^{LU}
 opponent

 Professor Nauta, Bram, MESA+ Research Institute, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands
 organization
 publishing date
 2004
 type
 Thesis
 publication status
 published
 subject
 keywords
 pipelined A/D converter, sigmadelta modulator, differential difference comparator, 2step A/D converter, FIR filter, analog filter, thermal noise, clock jitter, subsampling, RF sampling, currentmode sampling, Charge samling, A/D converter, flexible A/D converter, Electronics and Electrical technology, Elektronik och elektroteknik
 pages
 150 pages
 publisher
 Department of Electroscience, Lund University
 defense location
 Room E2311, Ebuilding, Lund Institute of Technology, Sweden
 defense date
 20040528 10:15
 ISSN
 14028662
 language
 English
 LU publication?
 yes
 id
 0bb9636a0d1347d2919b8ba7ac32e403 (old id 21795)
 date added to LUP
 20070528 14:40:43
 date last changed
 20160919 08:44:53
@phdthesis{0bb9636a0d1347d2919b8ba7ac32e403, abstract = {The analysis of general charge sampling technique is presented in this thesis. Charge sampling integrates input current instead of tracking input voltage to realize high speed and low voltage sampling. The analysis focuses on the performance of general charge sampling circuits for signal capture. The theoretical analysis here can be applied not only for the weak signal capture, but also for the normal signal sampling. Based on a general charge sampling model, the transfer function, the noise performance and the clock jitter tolerance are analyzed and compared to conventional voltage sampling. The results provide a theoretical basis for the charge sampling circuit design. The extended work for an accurate sampleandhold circuit model with a finite sampling duration is also presented. The results provide a better theoretical basis for understanding and designing a sampleandhold circuit with finite tracking time, especially when considering the RF sampling (or subsampling) and kT/C noise.<br/><br> <br/><br> A CMOS 6switch charge sampler is developed based on the charge sampling principle. With dummy capacitors operating alternatively in positive and negative branches, the resetting phase is embedded in the charging phase. The speed of the sampling is improved. A 500 MS/s charge sampling circuit was implemented in a 0.25 $mu$m CMOS process and measured. The dynamic range reaches 42 dB within the 250 MHz bandwidth. The power consumption is about 5 mW.<br/><br> <br/><br> Based on the principle of charge sampling, a novel charging FIR filters was suggested and implemented. The proposed FIR filter functions by summing the weighted current signal on a passive capacitor. First, the input signal is weighted by a resistor ladder, whose resistance is decided by the impulse response of the FIR filter. A linear transconductor then converts the weighted voltage to current and charges the capacitor linearly. The hardware cost is not proportional to the tap number in the proposed FIR filter. Two 32tap filter prototypes were implemented in the AMS 0.35 $mu$m CMOS process. For the first filter, the measured sideband attenuation reaches 60 dB. The group delay is lower than 11 ns. The power consumption is about 35 mW under 3.3 V supply voltage. For the second one, the measured sideband attenuation is about 40 dB. The group delay is about 50 ns. The power consumption is about 7 mW under 2 V supply voltage.<br/><br> <br/><br> A differential difference comparator (DDC) is proposed for A/D conversion. The proposed DDC provides easy linear voltage subtraction and comparison functions via current operation. Since there are no feedback loops, the speed of the analog signal subtraction is inherently faster when being used in an analogtodigital converter. Based the DDC, a CMOS pingpang mode 200 MS/s 8 bit 2step subranging A/D converter was implemented in the AMS 0.35 $mu$m CMOS process. Because of mismatch, the measured DNL for one branch is about 1.5 LSB and INL is about 2.2 LSB at 100 MS/s. The measured spurious free dynamic range at 100 MS/s (one branch) is 51 dB with 50 kHz sine input, while 39.2 dB at 200 MS/s (two branches) with 600 kHz signal input. The power consumption is 170 mW at 200 MS/s.<br/><br> <br/><br> Some other results on the A/D converters, such as an 80 dB sigmadelta modulator and a programmable A/D converter, are also included in the thesis. These works focus on the feasibility and flexibility study of the sigmadelta and pipelined A/D converters.}, author = {Xu, Gang}, issn = {14028662}, keyword = {pipelined A/D converter,sigmadelta modulator,differential difference comparator,2step A/D converter,FIR filter,analog filter,thermal noise,clock jitter,subsampling,RF sampling,currentmode sampling,Charge samling,A/D converter,flexible A/D converter,Electronics and Electrical technology,Elektronik och elektroteknik}, language = {eng}, pages = {150}, publisher = {Department of Electroscience, Lund University}, school = {Lund University}, title = {Charge Sampling Circuits and A/D Converters  Theory and Experiments}, year = {2004}, }