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Widely programmable high-frequency active RC filters in CMOS technology
, Tonse Laxminidhi, Venkata Prasadu
Published in Institute of Electrical and Electronics Engineers Inc.
2009
Volume: 56
   
Issue: 2
Pages: 327 - 336
Abstract
We propose a circuit technique that enables the realization of widely programmable high-frequency active RC filters in CMOS technology. A fifth-order Chebyshev ladder filter having a digitally programmable 3-dB bandwidth (from 44 to 300 MHz) is used as a vehicle to validate our ideas. The opamp uses feedforward compensation for achieving high dc gain and wide bandwidth. The integrating resistors are realized as a series combination of a triode-operated MOSFET and a fixed polysilicon resistor. A charge-pump-based servo loop servoes the integrating resistor to a stable off-chip resistor. The principle of "constant capacitance scaling"is applied to the opamp and the integrating resistors so that the shape of the frequency response is maintained when the bandwidth is scaled over a 7 7times; range. The filter core, designed in a 0.18-μm CMOS process, consumes 54 mW from 1.8-V supply and has a dynamic range of 56.6 dB. © 2009 IEEE.
About the journal
JournalData powered by TypesetIEEE Transactions on Circuits and Systems I: Regular Papers
PublisherData powered by TypesetInstitute of Electrical and Electronics Engineers Inc.
ISSN10577122
Open AccessNo
Concepts (15)
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    Active filters
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    Analog to digital conversion
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    Bandwidth
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    Cmos integrated circuits
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    Continuous time systems
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    Operational amplifiers
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    Polysilicon
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    Resistors
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    Telecommunication systems
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    CMOS
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    Compensation
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    Continuous-time
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    FEEDFORWARD
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    Programmable
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    Frequency response