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Analysis and design of discrete‐time charge domain filters with complex conjugate poles
Author(s) -
Sohrabi Zahra,
Jannesari Abumoslem
Publication year - 2017
Publication title -
international journal of circuit theory and applications
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.364
H-Index - 52
eISSN - 1097-007X
pISSN - 0098-9886
DOI - 10.1002/cta.2241
Subject(s) - integrator , filter (signal processing) , butterworth filter , control theory (sociology) , filter design , electronic filter topology , chebyshev filter , constant k filter , complex conjugate , transfer function , low pass filter , active filter , transconductance , passive integrator circuit , voltage controlled filter , m derived filter , time domain , discrete time and continuous time , electronic engineering , computer science , prototype filter , mathematics , engineering , rc circuit , electrical engineering , voltage , telecommunications , capacitor , mathematical analysis , bandwidth (computing) , artificial intelligence , control (management) , computer vision , statistics , transistor
Summary This paper proposes a discrete‐time charge domain filter that achieves complex conjugate poles in the transfer function of the filter. To achieve complex conjugate poles, local feedbacks are inserted around two successive discrete‐time integrators. The feedback path is implemented through a transconductance cell which applies a continuous time current into the integrators. Analytical models have been proposed to approximate the behavior of the filter. These models confirm that the structure is capable of realizing complex poles and thus can be used to synthesize any type of filter structures such as Butterworth, Chebysheve, etc. To show the effectiveness of the proposed architecture, Butterworth filters of order 2 and 4 operating at 50MS/s are designed and implemented in 180‐nm CMOS technology with 1.8‐V power supply. The effect of circuit nonidealities on the performance of the filter is analyzed and verified through simulations. Simulation results show that a conventional charge domain filter can be simply extended to implement complex conjugate poles while the noise and linearity performance of the filter are also improved. Copyright © 2016 John Wiley & Sons, Ltd.