Datasheet

10k
100k 1M 10M
FREQUENCY (Hz)
50
55
60
65
70
75
80
85
90
95
100
GAIN (dB)
C
IN
= 50 pF, C
F
= 4.5 pF
C
IN
= 100 pF, C
F
= 6 pF
C
IN
= 200 pF, C
F
= 9 pF
10k
100k 1M 10M
FREQUENCY (Hz)
50
60
70
80
90
100
110
120
130
GAIN (dB)
C
IN
= 50 pF, C
F
= 1.5 pF
C
IN
= 100 pF, C
F
= 2 pF
C
IN
= 200 pF, C
F
= 3 pF
LMV791, LMV792
SNOSAG6F –SEPTEMBER 2005–REVISED MARCH 2013 www.ti.com
Figure 60. Frequency Response for A
TI
= 470000
Figure 61. Frequency Response for A
TI
= 47000
HIGH GAIN WIDEBAND TRANSIMPEDANCE AMPLIFIER USING THE LMV792
The LMV792, dual, low noise, wide bandwidth, CMOS input op amp IC can be used for compact, robust and
integrated solutions for sensing and amplifying wide-band signals obtained from sensitive photodiodes. One of
the two op amps available can be used to obtain transimpedance gain while the other can be used for amplifying
the output voltage to further enhance the transimpedance gain. The wide bandwidth of the op amps (17 MHz)
ensures that they are capable of providing high gain for a wide range of frequencies. The low input referred noise
(5.8 nV/√Hz) allows the amplifier to deliver an output with a high SNR (signal to noise ratio). The small VSSOP-
10 footprint saves space on printed circuit boards and allows ease of design in portable products.
The circuit shown in Figure 62, has the first op amp acting as a transimpedance amplifier with a gain of 47000,
while the second stage provides a voltage gain of 10. This provides a total transimpedance gain of 470000 with a
−3 dB bandwidth of about 1.5 MHz, for a total input capacitance of 50 pF. The frequency response for the circuit
is shown in Figure 63
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