对于设计RF SOC接收机中频信道选择模块很有用:continue time filter

refinder

对于设计RF SOC接收机中频信道选择模块很有用！
Continuous-Time Filters from 0.1Hz to 2.0 GHz
Edgar Sánchez-Sinencio
Analog and Mixed-Signal Center, Texas A&M University
E-mail: sanchez@ee.tamu.edu
Abstract.-The bipolar transconductance amplifier (OTA) was commercially introduced in
1969 by RCA. Designers began using OTAs in the middle 80’s, since then the CMOSOTA
has becoming a vital component in a number of electronic circuits, both in open
loop and in closed loop applications. Here, we will focus on open loop applications.
Continuous-time filters implemented with transconductance amplifiers and capacitors
known as Gm-C or OTA-C are very popular for a host of applications. These applications
involve frequency of operation from a few tents of a hertz up to several gigahertz. Several
of those applications are in medical electronics and seismic area where the frequency
range is between 0.1Hz up to 20Hz. Other applications in the audio range do not
commonly use OTA-C filters because switched-capacitor techniques excel in this range.
But for frequency range of a few MHz like in Intermediate Frequency (IF) filters in RF
receivers OTA-C implementations are very attractive. For a few GHz range applications
where the OTA becomes a simple differential pair there is number of researchers
investigating LC-oscillators and filters. In this tutorial we discuss practical
implementations of transconductance amplifiers oriented for wide range of applications
for example in medical, IF filters, hard disk drive linear phase filters, LC-oscillators and
RF filters. Furthermore the unavoidable tuning scheme to compensate the Gm/C
deviations due to process technology variations is discussed. OTA single ended, fully
differential and pseudo differential versions are introduced together with the commonmode
feedback circuits needed for proper operation of differential architectures.

[ 本帖最后由 refinder 于 2007-12-8 23:06 编辑 ]

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