OPA2652
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SBOS125A–JUNE 2000–REVISED MAY 2006
APPLICATIONS INFORMATION
Wideband Voltage Feedback Operation
Voltage swings reported in the specifications are
taken directly at the input and output pins, while
output powers (dBm) are at the matched 50Ω load.
For the circuit of Figure 28, the total effective load
will be 100Ω || 804Ω. Two optional components are
included in Figure 28.
The OPA2652 is a dual, low-power, wideband
voltage feedback operational amplifier. Each channel
is internally compensated to provide unity gain
stability. The OPA2652 voltage feedback architecture
features true differential and fully symmetrical inputs.
This architecture minimizes offset errors, making the
OPA2652 well-suited for implementing filter and
An additional resistor (174Ω) is included in series
with the noninverting input. Combined with the 25Ω
DC source resistance looking back towards the
signal generator, this additional resistor gives an
input bias current cancelling resistance that matches
the 201Ω source resistance seen at the inverting
input (see the DC Accuracy and Offset Control
section). In addition to the usual power-supply
decoupling capacitors to ground, a 0.1µF capacitor is
included between the two power-supply pins. In
practical printed circuit board (PCB) layouts, this
optional-added capacitor typically improves the
2nd-harmonic distortion performance by 3dB to 6dB.
instrumentation designs. As
a dual operational
amplifier, OPA2652 is an ideal choice for designs
that require multiple channels where reduction of
board space, power dissipation and cost are critical.
Its AC performance is optimized to provide a gain
bandwidth product of 200MHz and a fast rise time of
2.0ns, which is an important consideration in
high-speed data conversion applications. The low
DC input offset of ±1.5mV and drift of ±5µV/°C
support high accuracy requirements. In applications
requiring a higher slew rate and wider bandwidth,
such as video and high bit rate digital
communications, consider the dual current feedback
OPA2694, or the OPA2691.
Figure 29 shows the DC-coupled, gain of –1, bipolar
supply circuit configuration that is the basis of the
specifications and typical characteristics at G = –1.
The input impedance matching resistor (57.6Ω) used
for testing gives a 50Ω input load. A resistor (205Ω)
connects the noninverting input to ground. This
configuration provides the DC source resistance
matching to cancel outputs errors arising from input
bias current.
Figure 28 shows the DC-coupled, gain of +2, dual
power-supply circuit configuration used as the basis
of the ±5V specifications and typical characteristics.
This configuration is for one channel. The other
channel is connected similarly. For test purposes, the
input impedance is set to 50Ω with a resistor to
ground and the output impedance is set to 50Ω with
a series output resistor.
+5V
+5V
+
0.1mF
6.8mF
0.1mF
6.8mF
+
0.1mF
RO
49.9W
50W Source
174W
VO
1/2
OPA2652
RB
205W
50W Load
VO 49.9W
VI
50W Load
1/2
OPA2652
49.9W
VO
VI
= -1
50W
Source
VI
RG
402W
RF
402W
0.1mF
RF
402W
RM
57.6W
RG
0.1mF
6.8mF
402W
+
6.8mF
+
0.1mF
-5V
-5V
Figure 29. DC-Coupled, G = –1, Bipolar Supply,
Specification and Test Circuit
Figure 28. DC-Coupled, G = +2, Bipolar Supply,
Specification and Test Circuit
10
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