EL4451C

Wideband Variable-Gain Amplifier Gain of 2

Applications Information

Contd

Here is the EL4451 used as an oscillator with simple AGC

Low-Distortion Sinewave Oscillator

4451 – 33

The oscillation frequency is set by the resonance

of a series-tuned circuit which may be an L-C

combination or a crystal At resonance the series

impedance of the tuned circuit drops and its

phase lag is 0

so the EL4451 needs a gain just

gain in the EL4451 At such high gain the loop

mately reducing gain until a stable 05Vrms out-

put is produced

Using a 2 MHz crystal output distortion was

b

53 dBc or 022% Sideband modulation was

of the spectrum analyzer used

The circuit works up to 30 MHz A parallel-tuned

circuit can replace the 510

X resistor and the 510X

resistor moved in place of the series-tuned ele-

ment to allow grounding of the tuned compo-

nents

Filters

The EL4451 can be connected to act as a voltage-

variable integrator as shown

EL4451 Connected As Variable Integrator

4451 – 34

The input RC cancels a zero produced by the out-

put op-amp feedback connection at

This variable integrator may be used in networks

such as the Bi-quad In some applications the in-

put RC may be omitted If a negative gain is re-

exchanged

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