Datasheet
1/2
OPA2695
+5V
+V
S
-V
S
DIS
-5V
50 LoadW
50W
20W
R
T
562W
R
G
54.9W
+
6.8 Fm0.1 Fm
+
6.8 Fm0.1 Fm
Optional
0.01 Fm
V
I
50 SourceW
R
F
442W
V
O
1/2
OPA2695
+5V
+V
S
DIS
50 LoadW
50W
R
G
50W
806W
806W
57.6W
0.1 Fm1000pF
+
6.8 Fm0.1 Fm
0.1 Fm
0.1 Fm
V
I
50 SourceW
R
F
348W
V
O
1000pF
1000pF
OPA2695
SBOS354A – APRIL 2008 – REVISED AUGUST 2008 ......................................................................................................................................................
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ranges at both the input and the output. The circuit of
Figure 70 establishes an input midpoint bias using a
simple resistive divider from the +5V supply (two
806 Ω resistors) to the noninverting input. The input
signal is then ac-coupled into this midpoint voltage
bias. The input voltage can swing to within 1.6V of
either supply pin, giving a 1.8V
PP
input signal range
centered between the supply pins. The input
impedance matching resistor (57.6 Ω ) used in
Figure 70 is adjusted to give a 50 Ω input match when
the parallel combination of the biasing divider network
is included. The gain resistor (R
G
) is ac-coupled,
giving the circuit a dc gain of +1. This configuration
puts the input dc bias voltage (2.5V) on the output as
well. The feedback resistor value has been adjusted
from the bipolar supply condition to re-optimize for a
flat frequency response in +5V only, gain of +8
operation (see Setting Resistor Values to Optimize
Bandwidth ). On a single +5V supply, the output
voltage can swing to within 1.0V of either supply pin
while delivering more than 90mA output current,
giving 3V output swing into 100 Ω (7dBm maximum at
the matched load). The circuit of Figure 70 shows a
Figure 69. DC-Coupled, G = – 8V/V, Bipolar Supply
blocking capacitor driving into a 50 Ω output resistor,
Specifications and Test Circuit
then into a 50 Ω load. Alternatively, the blocking
capacitor could be removed with the load tied to a
Figure 70 shows the ac-coupled, single +5V supply,
supply midpoint or to ground if the dc current required
gain of +8V/V circuit configuration used as a basis for
by this grounded load is acceptable.
the +5V only Electrical Characteristics and Typical
Characteristics . The key requirement for broadband
single-supply operation is to maintain input and
output signal swings within the useable voltage
Figure 70. AC-Coupled, G = +8V/V, Single-Supply Specifications and Test Circuit
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