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Front. Inform. Technol. Electron. Eng.  2010, Vol. 11 Issue (4): 307-314    DOI: 10.1631/jzus.C0910390
    
Discrete-time charge analysis for a digital RF charge sampling mixer
Yun Pan*,1, Ning Ge2, Xiao-lang Yan1, Xiao-peng Yu1
1 Institute of VLSI Design, Zhejiang University, Hangzhou 310027, China 2 Department of Electronic Engineering, Tsinghua University, Beijing 100084, China
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Abstract  This paper presents an approach for analyzing the key parts of a general digital radio frequency (RF) charge sampling mixer based on discrete-time charge values. The cascade sampling and filtering stages are analyzed and expressed in theoretical formulae. The effects of a pseudo-differential structure and CMOS switch-on resistances on the transfer function are addressed in detail. The DC-gain is restrained by using the pseudo-differential structure. The transfer gain is reduced because of the charge-sharing time constant when taking CMOS switch-on resistances into account. The unfolded transfer gains of a typical digital RF charge sampling mixer are analyzed in different cases using this approach. A circuit-level model of the typical mixer is then constructed and simulated in Cadence SpectreRF to verify the results. This work informs the design of charge-sampling, infinite impulse response (IIR) filtering, and finite impulse response (FIR) filtering circuits. The discrete-time approach can also be applied to other multi-rate receiver systems based on charge sampling techniques.

Key wordsDigital RF      Charge sampling      Discrete-time      Pseudo-differential      Switch-on resistance     
Received: 01 July 2009      Published: 22 March 2010
CLC:  TN710  
Fund:   Project  supported  by  the  National  Natural  Science  Foundation  of China (No. 90407011), the National High-Tech Research and Devel-
opment  Program  (863)  of  China  (No.  2007AA01Z2b3),  and  China Postdoctoral Science Foundation (No. 20090451439)
Cite this article:

Yun Pan, Ning Ge, Xiao-lang Yan, Xiao-peng Yu. Discrete-time charge analysis for a digital RF charge sampling mixer. Front. Inform. Technol. Electron. Eng., 2010, 11(4): 307-314.

URL:

http://www.zjujournals.com/xueshu/fitee/10.1631/jzus.C0910390     OR     http://www.zjujournals.com/xueshu/fitee/Y2010/V11/I4/307


Discrete-time charge analysis for a digital RF charge sampling mixer

This paper presents an approach for analyzing the key parts of a general digital radio frequency (RF) charge sampling mixer based on discrete-time charge values. The cascade sampling and filtering stages are analyzed and expressed in theoretical formulae. The effects of a pseudo-differential structure and CMOS switch-on resistances on the transfer function are addressed in detail. The DC-gain is restrained by using the pseudo-differential structure. The transfer gain is reduced because of the charge-sharing time constant when taking CMOS switch-on resistances into account. The unfolded transfer gains of a typical digital RF charge sampling mixer are analyzed in different cases using this approach. A circuit-level model of the typical mixer is then constructed and simulated in Cadence SpectreRF to verify the results. This work informs the design of charge-sampling, infinite impulse response (IIR) filtering, and finite impulse response (FIR) filtering circuits. The discrete-time approach can also be applied to other multi-rate receiver systems based on charge sampling techniques.

关键词: Digital RF,  Charge sampling,  Discrete-time,  Pseudo-differential,  Switch-on resistance 
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