TIME (1 Ps/DIV)

0.8

0.4

0.0

-0.4

-0.8

LMP7701

LMP7707 compensated

TIME (1 Ps/DIV)

0

0

0

uncompensated

compensated

overcompensated

LMP7707, LMP7708, LMP7709

SNOSAW5B – JUNE 2007 – REVISED MARCH 2013

www.ti.com

Figure 60 shows the results of the compensation of the LMP7707.

Figure 60. Bench Results for Lead- Lag Compensation

The top waveform shows the output response of a uncompensated LMP7707 using no external compensation

components. This trace shows ringing and is unstable (as expected). The middle waveform is the response of a

compensated LMP7707 using the compensation components calculated with the described procedure. The

response is reasonably well behaved. The bottom waveform shows the response of an overcompensated

LMP7707.

Finally, Figure 61 compares the step response of the compensated LMP7707 to that of the unity gain stable

LMP7701. The increase in dynamic performance is clear.

Figure 61. Bench Results for Comparison of LMP7701 and LMP7707

The application of input lead-lag compensation to a decompensated op amp enables the realization of circuit

gains of less than the minimum specified by the manufacturer. This is accomplished while retaining the

advantageous speed versus power characteristic of decompensated op amps.

28

Submit Documentation Feedback

Copyright © 2007–2013, Texas Instruments Incorporated

Product Folder Links: LMP7707 LMP7708 LMP7709