OPA4684 Datasheet, PDF (1/33 Pages) Burr-Brown (TI) – Quad, Low-Power, Current-Feedback OPERATIONAL AMPLIFIER

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OPA4684
OPA4684
OPA4684 ®
SBOS240G – JUNE 2002 – REVISED JULY 2008
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 ±2.5 TO ±6.0V SUPPLY OPERATION
q LOW SUPPLY CURRENT: 1.7mA/ch
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 INPUT
DRIVERS
q MULTIPLE POLE ACTIVE FILTERS
q OPA4658 LOW-POWER UPGRADE
DESCRIPTION
The OPA4684 provides a new level of performance in low-
power, wideband, current-feedback (CFB) amplifiers. This
CFB_PLUS amplifier is among the first to use an internally
closed-loop input buffer stage that enhances performance
significantly over earlier low-power CFB amplifiers. This new
architecture provides many of the benefits of a more ideal
CFB amplifier while retaining the benefits of very low power
operation. 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
high-gain applications, the OPA4684 CFB_PLUS amplifier per-
mits the gain setting element to be set with considerable
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 ±4V_PP 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.
V+
1 of 4 Channels
+
V_O
V–
I_ERR
Z_(S) I_ERR
R_F
R_G
Low-Power
Amplifier
(patented design)
6
3
0
–3
–6
–9
–12
–15
–18
–21
–24 ^{RF = 800Ω}
10
BW (MHz) vs GAIN
G=1
G=2
G=5
G = 10
G = 20
G = 50
G = 100
100
200
MHz
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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.
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