OPA2684IDCNT Datasheet, PDF (1/34 Pages) Texas Instruments – Low-Power, Dual Current-Feedback OPERATIONAL AMPLIFIER

OPA2684
OPA2684
www.ti.com
SBOS239D – APRIL 2002 – REVISED JULY 2008
Low-Power, Dual 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: < –82dBc 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: 3.4mA Total
DESCRIPTION
The OPA2684 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. 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
high-gain applications, the OPA2684 CFB_PLUS amplifier per-
mits the gain setting element to be set with considerable
APPLICATIONS
q SHORT-LOOP ADSL CO DRIVER
q LOW-POWER BROADCAST VIDEO DRIVERS
q DIFFERENTIAL EQUALIZING FILTERS
q DIFFERENTIAL SAW FILTER POST AMPLIFIER
q MULTICHANNEL SUMMING AMPLIFIERS
q PROFESSIONAL CAMERAS
q ADC INPUT DRIVERS
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 OPA2684 also sets a new mark
in performance for low-power, current-feedback amplifiers.
Delivering a full ±4Vp-p swing on ±5V supplies, the OPA2684
also has the output current to support > ±3Vp-p into 50Ω
loads. This minimal output headroom requirement is comple-
mented by a similar 1.2V input stage headroom giving
exceptional capability for single +5V operation.
The OPA2684’s low 3.4mA 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 2 Channels
+
V_O
V–
I_ERR
Z_(S) I_ERR
R_F
R_G
Low-Power
Amplifier
US Patent #6,724,260
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
MHz
100
200
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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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