DiscoverCircuits.com, has 30,000+ electronic
circuits, cross-referenced
into 500+ categories. We have searched the web to help you
find quick design ideas.
We make every effort to link to material posted by the designer.
Please let us if you would like us to link to or post your
design.
Notch Filter is DC Accurate - 03/02/95 EDN-Design Ideas....Most
active filters exhibit noise, distortion, gain error, and dc offset.
However, a filter topology that separates the dc and ac paths can eliminate
the last two of these unwanted behaviors (Fig 1a). The dc path in this
circuit has no op amps and, therefore, no dc offset. The dc path does not
have a dc gain error other than -6 dB of attenuation that the R1/R2 divider
causes. (This attenuation is absent if you omit the R2 termination.) The ac
path consists of C1 and a synthetic inductor comprising two wideband
transconductance amplifiers and associated components. The result is an
active circuit that emulates the passive filter of Fig 1b....[Design Idea by
Gary Sellani, Maxim Integrated Products, Sunnyvale, CA]
Notch RC Notch Filter Twin T - The twin T notch filter can be used
block an unwanted frequency or if placed around an op-amp as a bandpass
filter. The notch frequency occurs where the capacitive reactance equals the
resistance Xc=R and if the values are close, the attenuation can be very
high and the notch frequency virtually eliminated. (electronic schematic /
circuit added 4/02)
