1 -1 . I NTRODUCTION
S ECTI O N I
G ENERAL I N F ORMAT I ON
The Models 452 ond 852 ore versati l e dual -channel fi l ters consisting of twa
identicol channel s in a common cabi net . Each fi lter channe l has seporate
input/output tenmina l s , offers high poss and l aw poss functions,
0
dB and 20
dB gain, Butterworth and L inear Phase responses and 3-digit resol ution for
cutoff frequency sel e ction .
Individual channe l s moy be read i l y inte rconnected for series or para l le l
operation, resulting in bandpass (or doubled rol l off) and band re ject functions
respective l y .
Each fi l ter channel provides switch se l e ctabl e F l at Am plitude (Butterworth)
response and F l at De loy (Linear Phase) response .
The B utterworth fi lter has maxima l l y-flat ampl itude response suitabl e for
frequency-domain appli cations. Its cutoff frequency (fc) is defined as the
frequency at whi ch the amplitude response is down 3 dB .
The Linear Phase fi l ter approximates a constant time delay for frequencies
below its cutoff frequency. This fi l ter is suitable for time-domain appl i cations
because o f its inherent obi l ity to poss transient waveforms with a very sma l l
amount of d istortion and overshoot.
Models 452 ond 852 are e lectrica l l y and mechani ca l ly sim i l or, covering the
cutoff frequency range of 0 . 1 Hz to 1 1 1 K Hz . Rol l off of the Mode l 452 is 2 4 dB/
o ctave/channe l , Madel 852 is 48 dB/octave/channel . Factory-instal led
Option
-01
extends cutoff frequency range and resol ution on bath models to
0.01
Hz .
Frequency-determining possive e l ements of the fi lters consist of stable precision
metal fi l m resistors and cl ose tole rance po l ycarbonate or m i ca fi lm capacitors .
The a ctive e lements are F ET -input IC aperotional ampl ifiers which provide
high l y stab l e gain, and very l ow noise and d istortion. This combination of active
and passive e l ements produces a fi l ter having high cutoff frequency accuracy ond
resettab i l ity, and exce l lent temperature and l ong tenm stabi l ity . Another resul t
o f pre cise control o f frequency-determining e lements is c l ose ampl i tude and phase
match between channe l s .
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Summary of Contents for 452
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