OPA3684 Datasheet, PDF (1/32 Pages) Burr-Brown (TI) – Low-Power, Triple Current-Feedback OPERATIONAL AMPLIFIER With Disable

OPA3684
OPA3684
www.ti.com
SBOS241C – MAY 2002 – REVISED JULY 2008
Low-Power, Triple Current-Feedback
OPERATIONAL AMPLIFIER With Disable
FEATURES
q MINIMAL BANDWIDTH CHANGE VERSUS GAIN
q 170MHz BANDWIDTH: G = +2
q > 120MHz BANDWIDTH TO GAIN > +10
q LOW DISTORTION: < –82dBc at 5MHz
q HIGH OUTPUT CURRENT: 120mA
q SINGLE +5V TO +12V SUPPLY OPERATION
q DUAL ±2.5V TO ±6.0V SUPPLY OPERATION
q LOW SUPPLY CURRENT: 1.7mA/ch
q LOW SHUTDOWN CURRENT: 100µA/ch
APPLICATIONS
q RGB LINE DRIVERS
q LOW-POWER BROADCAST VIDEO DRIVERS
q EQUALIZING FILTERS
q MULTICHANNEL SUMMING AMPLIFIERS
q PROFESSIONAL CAMERAS
q ADC INPUT DRIVERS
DESCRIPTION
The OPA3684 provides a new level of performance in low-power,
wideband, current-feedback (CFB) amplifiers. This CFB_PLUS am-
plifier among the first to use an internally 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 solu-
tions limited by inverting input linearity. Beyond simple high-gain
applications, the OPA3684 CFB_PLUS amplifier permits 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 requirements of studio cameras and broadcast video.
The output capability of the OPA3684 also sets a new mark in
performance for low-power current-feedback amplifiers. Delivering
a full ±4Vp-p swing on ±5V supplies, the OPA3684 also has the
output current to support > ±3Vp-p into 50Ω. This minimal output
headroom requirement is complemented by a similar 1.2V input
stage headroom giving exceptional capability for single +5V opera-
tion.
The OPA3684’s low 1.7mA/ch 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. System power may be further reduced by using the
optional disable control pin. Leaving this disable pin open, or holding
it HIGH, gives normal operation. If pulled LOW, the OPA3684 supply
current drops to less than 100µA/ch while the I/O pins go to a high
impedance state.
1 of 3 Channels
V+
+
V_O
V–
I_ERR
Z_(S) I_ERR
R_F
R_G
Low-Power
Amplifier
Patent Pending
6
3
0
–3
–6
–9
–12
–15
–18
–21 _{RF = 800Ω}
–24
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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