OPA4684M Datasheet, PDF (17/32 Pages) Texas Instruments – QUAD LOW-POWER CURRENT-FEEDBACK OPERATIONAL AMPLIFIER

OPA4684M
QUAD LOWĆPOWER CURRENTĆFEEDBACK
OPERATIONAL AMPLIFIER
SGLS145B − AUGUST 2003 − REVISED FEBRUARY 2004
Figure 46. Inverting Differential I/O Amplifier
The two noninverting inputs provide an easy common-mode control input. This is particularly useful if the source
is AC-coupled through either blocking caps or a transformer. In either case, the common-mode input voltages
on the two noninverting inputs again have a gain of 1 to the output pins, giving an easy common-mode control
for single-supply operation. The OPA4684 used in this configuration does constrain the feedback to the 800ý
region for best frequency response. With R_F fixed, the input resistors may be adjusted to the desired gain but
will also be changing the input impedance as well. The differential gain for this circuit is:
V_O
V_I
+
*
R_F
R_G
low-power video line driver applications
For low-power, video line driving, the OPA4684 provides the output current and linearity to support 4 channels
of either single video lines, or up to 4 video lines in parallel on each output. Figure 47 shows a typical ±5V supply
video line driver application where only one channel is shown and only a single line is being driven. The improved
2nd-harmonic distortion of the CFB_PLUS architecture, along with the OPA684’s high output current and voltage,
gives exceptional differential gain and phase performance for a low-power solution. As the Typical
Characteristics show, a single video load shows a dG/dP of 0.04%/0.02°. Multiple loads may be driven on each
output, with minimal x-talk, while the dG/dP is still < 0.1%/0.1° for up to 4 parallel video loads.
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