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LMF100_15 Datasheet, PDF (33/40 Pages) Texas Instruments – LMF100 Dual High-Performance Switched Capacitor Filters
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12 Device and Documentation Support
LMF100
SNOSBG9B – JULY 1999 – REVISED JUNE 2015
12.1 Device Support
12.1.1 Device Nomenclature
12.1.1.1 Definitions of Terms
fCLK: the frequency of the external clock signal applied to pin 10 or 11.
f0: center frequency of the second order function complex pole pair. f0 is measured at the bandpass outputs of
the LMF100, and is the frequency of maximum bandpass gain. (Figure 25).
fnotch: the frequency of minimum (ideally zero) gain at the notch outputs.
fz: the center frequency of the second order complex zero pair, if any. If fz is different from f0 and if Qz is high, it
can be observed as the frequency of a notch at the allpass output. (Figure 46).
Q: “quality factor” of the 2nd order filter. Q is measured at the bandpass outputs of the LMF100 and is equal to f0
divided by the −3 dB bandwidth of the 2nd order bandpass filter (Figure 25). The value of Q determines the shape
of the 2nd order filter responses as shown in Figure 35.
Qz: the quality factor of the second order complex zero pair, if any. QZ is related to the allpass characteristic,
which is written:
HAP (s)
=
HOAP
æ
ççè s2
-
swo + wo2
Qz
s2
-
swo
Q
+ wo2
ö
÷÷ø
where QZ = Q for an allpass response.
HOLP: the gain (in V/V) of the lowpass output as f → 0 Hz (Figure 27).
HOHP: the gain (in V/V) of the highpass output as f → fCLK/2 (Figure 29).
HON: the gain (in V/V) of the notch output as f → 0 Hz and as f → fCLK/2, when the notch filter has equal gain
above and below the center frequency (Figure 31 ). When the low-frequency gain differs from the high-frequency
gain, as in modes 2 and 3a (Figure 43 and Figure 45), the two quantities below are used in place of HON.
HON1: the gain (in V/V) of the notch output as f → 0 Hz.
HON2: the gain (in V/V) of the notch output as f → fCLK/2.
12.2 Community Resources
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contributors. They do not constitute TI specifications and do not necessarily reflect TI's views; see TI's Terms of
Use.
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12.3 Trademarks
LMCMOS, E2E are trademarks of Texas Instruments.
All other trademarks are the property of their respective owners.
Copyright © 1999–2015, Texas Instruments Incorporated
Product Folder Links: LMF100
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