OPA4

684

®

OPA4

684

PRODUCTION DATA information is current as of publication date.

Products conform to specifications per the terms of Texas Instruments

standard warranty. Production processing does not necessarily include

testing of all parameters.

OPA4684

www.ti.com

Copyright © 2002, Texas Instruments Incorporated

Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of

Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.

SBOS240B – JUNE 2002 – REVISED AUGUST 2002

Quad, Low-Power, Current-Feedback

OPERATIONAL AMPLIFIER

FEATURES

q MINIMAL BANDWIDTH CHANGE VERSUS GAIN

q 170MHz BANDWIDTH AT G = +2

q > 120MHz BANDWIDTH TO GAIN > +10

q LOW DISTORTION: < –78dBc at 5MHz

q HIGH OUTPUT CURRENT: 120mA

q SINGLE +5V TO +12V SUPPLY OPERATION

q DUAL

q LOW SUPPLY CURRENT: 6.8mA Total

DESCRIPTION

The OPA4684 provides a new level of performance in low-

power, wideband, current-feedback (CFB) amplifiers. This

closed-loop input buffer stage that enhances performance

significantly over earlier low-power CFB amplifiers. While

retaining the benefits of very low power operation, this new

architecture provides many of the benefits of a more ideal

CFB amplifier. The closed-loop input stage buffer gives a

very low and linearized impedance path at the inverting input

to sense the feedback error current. This improved inverting

input impedance retains exceptional bandwidth to much

higher gains and improves harmonic distortion over earlier

solutions limited by inverting input linearity. Beyond simple

mits the gain setting element to be set with considerable

APPLICATIONS

q LOW-POWER BROADCAST VIDEO DRIVERS

q EQUALIZING FILTERS

q SAW FILTER HIGH-GAIN POST AMPLIFIERS

q MULTICHANNEL SUMMING AMPLIFIERS

q WIDEBAND DIFFERENTIAL CHANNELS

q ANALOG-TO-DIGITAL CONVERTERS (ADC)

INPUT DRIVERS

q MULTIPLE POLE ACTIVE FILTERS

q OPA4658 LOW-POWER UPGRADE

freedom from amplifier bandwidth interaction. This allows

frequency response peaking elements to be added, multiple

input inverting summing circuits to have greater bandwidth,

and low-power line drivers to meet the demanding require-

ments of studio cameras and broadcast video.

The output capability of the OPA4684 also sets a new mark

in performance for low-power current-feedback amplifiers.

Delivering a full

±4Vp-p swing on ±5V supplies, the OPA4684

also has the output current to support >

±3V swing into 50Ω.

This minimal output headroom requirement is complemented

by a similar 1.2V input stage headroom giving exceptional

capability for single +5V operation.

The OPA4684’s low 6.8mA supply current is precisely trimmed

at 25

°C. This trim, along with low shift over temperature and

supply voltage, gives a very robust design over a wide range

of operating conditions.

Patent Pending

V+

V

O

V–

I

ERR

R

G

R

F

Z

+

Low-Power

Amplifier

1 of 4 Channels

6

3

0

–3

–6

–9

–12

–15

–18

–21

–24

R

G = 100

G = 50

G = 20

G = 10

G = 2

G = 1

10

100

200

BW (MHz) vs GAIN

G = 5

MHz