CLC431 datasheet(4/8 Pages) NSC

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Typical Performance plots are valid for both devices

under the specified conditions. Generally, lowering Rf

from its recommended value will peak the frequency

response and extend the bandwidth while increasing its

value will roll off the response. Reducing the value of Rf

too far below its recommended value will cause overshoot,

ringing and eventually oscillation. For more information

see Application Note OA-20 and OA-13.

In order to optimize the devices' frequency and phase

response for gains other than +2V/V it is recommended

to adjust the value of the feedback resistor. The two plots

found in the Typical Performance section entitled

"Recommended Rf vs. Gain" provide the means of

selecting the feedback-resistor value that optimizes

frequency and phase response over the CLC431/

CLC432's gain range. Both plots show the value of Rf

approaching a nonzero minimum at high non-inverting

gains, which is characteristic of current-feedback op

amps and yields best results. The linear portion of the

two Rf vs. Inverting-gain curves results from the limitation

placed on Rg (i.e. Rg

≥ 50Ω) in order to maintain an

adequate input impedance for the inverting configuration.

It should be noted that for stable operation a non-

inverting gain of +1 requires an Rf equal to 1k

Ω for both

the CLC431 and the CLC432.

CLC431 Disable Feature

The CLC431 disable feature can be operated either

single-endedly or differentially thereby accommodating a

wide range of logic families. There are three pins asso-

ciated with the disable feature of each of the CLC431's

two amplifiers: DIS DIS and V

RTTL

(please see pinout on

Introduction

The CLC431 and the CLC432 are dual wideband current-

feedback op amps that operate from single (+10V to

+33V) or dual (±5V to ±16.5) power supplies. The

CLC431 is equipped with a disable feature and is offered

in 14-pin DIP and SOIC packages. The CLC432 is

packaged in a standard 8-pin dual pinout and is offered

in an 8-pin DIP and SOIC. Evaluation boards are available

for each version of both devices. The evaluation boards

can assist in the device and/or application evaluation and

were used to generate the typical device performance

plots on the preceding pages.

Each of the CLC431/CLC432's dual channels provide

closely matched DC & AC electrical performance

characteristics making them ideal choices for wideband

signal processing. The CLC431, with its disable feature,

can easily be configured as a 2:1 mux or several can be

used to form a 10:1 mux without performance degradation.

The two closely-matched channels of the CLC432 can be

combined to form composite circuits for such applications

as filter blocks, integrators, transimpedance amplifiers

and differential line drivers and receivers.

Feedback Resistor Selection

The loop gain and frequency response for a current-

feedback operational amplifier is determined largely by

the feedback resistor (Rf). Package parasitics also

influence ac response. Since the package parasitics of

the CLC431 and the CLC432 are different, the optimum

frequency and phase responses are obtained with different

values of feedback resistor (for AV=+2; CLC431: Rf=866

Ω,

CLC432: Rf=750

Ω). The Electrical Characteristics and

Application Discussion

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