LMP7717, LMP7718

SNOSAY7H – MARCH 2007 – REVISED MARCH 2013

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Figure 64. Rise Time

In Figure 63 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 CF 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 CF. 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 65 shows the response for a 1V output.

Figure 65. High Gain Response

A transimpedance amplifier is an excellent application for the LMP7717. Even with the high gain using a 100 k

Ω

feedback resistor, the bandwidth is still well over 1 MHz. Other than a little over compensation for the 10 k

Ω

feedback resistor configuration using the LMP7717 was quite easy. Of course a very good board layout was also

used for this test.

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