Datasheet

OPA 836
Signal and bias to
next stage
Signal and bias
from previous stage
C
5 V
2.5 V
R
1
R
2
5 V
R
O
V
OUT
R
G
R
F
V
SIG
GV
SIG
2.5 V
OPA 836
V
OUT
Signal and bias to
next stage
Signal and bias
from previous stage
C
R
1
R
O
R
F
R
G
V
SIG
GV
SIG
5 V
5 V
2.5 V
REF
2.5 V
2.5 V
OPA836
OPA2836
www.ti.com SLOS712E –JANUARY 2011–REVISED SEPTEMBER 2013
Figure 65. Inverting Single Supply with Reference
Figure 66 shows a similar inverting single supply scenario with the reference generator replaced by the Thevenin
equivalent using resistors and the positive supply. R
1
and R
2
form a resistor divider from the 5 V supply and are
used to bias the positive side. To cancel the voltage offset that would otherwise be caused by the input bias
currents, set the parallel sum of R
1
and R
2
equal to the parallel sum of R
F
and R
G
. C should be added to limit
coupling of noise into the positive input. For example if gain of –2 is required and R
F
= 1 kΩ, select R
G
= 499 Ω
to set the gain. R
1
= R
2
= 665 Ω for mid supply voltage bias and for op amp input bias current cancellation. A
good value for C is 0.1 µF. This can be lower cost, but note the extra current draw required in the resistor divider.
Figure 66. Inverting Single Supply with Resistors
Pulse Application with Single-Supply
For pulsed applications, where the signal is at ground and pulses to some positive or negative voltage, the circuit
bias voltage considerations are different than with a signal that swings symmetrical about a reference point and
the circuit configuration should be adjusted accordingly. Figure 67 shows a pulsed situation where the signal is at
ground (0 V) and pulses to a positive value.
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