Datasheet

25 mV/DIV
1 Ps/DIV
V
+
= 1V
25 mV/DIV
1 Ps/DIV
V
+
= 1V
LMV951
www.ti.com SNOSAI3C –OCTOBER 2006–REVISED APRIL 2013
The chart below gives recommended values for some common values of large capacitors. For these values R
L
=
2 kΩ;
C
L
R
S
C
S
500 pF 330Ω 6800 pF
680 pF 270Ω 8200 pF
1000 pF 220Ω .015 μF
Figure 49. 1000 pF and no Snubber Figure 50. 1000 pF with Snubber
BRIDGE CONFIGURATION AMPLIFIER
Some applications may benefit from doubling the voltage across the load. With V
+
= 1V a bridge configuration
can provide a 2 V
PP
output to the load with a resistance as low as 300Ω. The output stage of the LMV951
enables it to drive a load of 120Ω and still swing at least 70% of the supply rails.
The bridge configuration shown in Figure 51 enables the amplifier to maintain a low dropout voltage thus
maximizing its dynamic range. It has been configured in a gain of 1 and uses the fewest number of parts.
Resistor values have been selected to keep the current consumption to a minimum and voltage errors due to
bias currents negligible. Using the selected resistor values makes this circuit quite practical in a battery operated
design. R
1
, R
2
and R
5
, R
6
set up a virtual ground that is half of V
+
. Note that the accuracy of the resistor values
will establish how well the two virtual grounds match. Any errors in the virtual grounds will show as current
across R
L
when there is no input signal.
AC coupling the input signal sets the DC bias point of this signal to the virtual ground of the circuit. Using the
large resistor values with a 1 µF capacitor (C
1
) sets the frequency rolloff of this circuit below 10 Hz.
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