Datasheet

LMV793, LMV794
www.ti.com SNOSAX6D –MARCH 2007–REVISED MARCH 2013
Figure 59. Rise Time
In Figure 58 the ringing and the hump during the on time is from the laser. The higher drive levels for the laser
gave ringing in the light source as well as light changing from the thermal characteristics. The hump is due to the
thermal characteristics.
Solving for C
F
using a 100 kΩ feedback resistor, the calculated value is 0.54 pF. One of the problems with more
gain is the very small value for C
F
. A 0.5 pF capacitor was used, its measured value being 0.64 pF. For the 0.64
pF location the pole is at 2.5 MHz. Figure 60 shows the response for a 1V output.
Figure 60. High Gain Response
A transimpedance amplifier is an excellent application for the LMV793. Even with the high gain using a 100 kΩ
feedback resistor, the bandwidth is still well over 1 MHz. Other than a little over compensation for the 10 kΩ
feedback resistor configuration using the LMV793 was quite easy. Of course a very good board layout was also
used for this test. For information on photo diodes please contact OSI Optoelectronics, [phone]. For
further information on transimpedance amplifiers please contact your Texas Instruments representative.
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