EL4452CS datasheet(10/12 Pages) ELANTEC

10 / 12 page

EL4452C

Wideband Variable-Gain Amplifier with Gain of 10

Applications Information

Contd

Most AGC’s deal with repetitive input signals

that are capacitively coupled It is generally de-

sirable to keep DC offsets from mixing with AC

signals and fooling the level detector into main-

taining the DC output offset level constant rath-

er than a smaller AC component To that end

either the level detector is AC-coupled or the ref-

erence voltage must be made greater than the

maximum multiplier gain times the input offset

For instance if the level detector output equaled

the reference voltage at 1V of EL4452 output the

8 mV of input offset would require a maximum

gain of 125 through the EL4452 Bias current-in-

duced offsets could increase this further

Depending on the nature of the signal different

level detector strategies will be employed If the

system goal is to prevent overload of subsequent

stages peak detectors are preferred Other strate-

gies use an RMS detector to maintain constant

output power Here is a simple AGC using peak

detection

4452 – 25

EL4452CS Datasheet(PDF) 10 Page - Elantec Semiconductor