Datasheet

ADA4075-2 Data Sheet
Rev. C | Page 20 of 24
LOW NOISE PARAMETRIC EQUALIZER
The circuit in Figure 69 is a reciprocal parametric equalizer
yielding ±20 dB of cut or boost with variable bandwidth and
frequency. The frequency control range is 6.9:1, with the geometric
mean center frequency conveniently occurring at the midpoint
of the potentiometer setting. The center frequency is equal to
48 Hz/Ct, where Ct is the value of C1 and C2 in microfarads.
The bandwidth control adjusts the Q from 0.9 to about 11. The
overall noise is setting dependent, but with all controls centered,
it is about −104 dBV in a 20 kHz bandwidth. Such a low noise
level can obviate the need for a bypass switch in many applications.
07642-074
1/2
C2*
100Ω
1kΩ
BANDWIDTH
*THE CENTER FREQUENCY
IS AFFECTED BY THE VALUE OF C1 AND C2
(SEE THE LOW NOISE PARAMETRIC EQUALIZER SECTION FOR MORE DE TAILS).
1.3kΩ
1/2
1/2
C1*
2.5kΩ
620Ω
2.5kΩ
620Ω
1.5kΩ
1.3kΩ
2.5kΩ
1/2
ADA4075-2
ADA4075-2
ADA4075-2ADA4075-2
6.2kΩ
6.2kΩ
47µF
5k
Ω
BOOST
CUT
1.5kΩ
IN
OUT
2.5kΩ
2.7kΩ
620
Ω
FREQUENCY (GANGED POTENTIOMETER)
Figure 69. Low Noise Parametric Equalizer