LMC6482-MIL Datasheet, PDF (21/31 Pages) Texas Instruments – CMOS Dual Rail-to-Rail Input and Output Operational Amplifier

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Typical Applications (continued)
LMC6482-MIL
SNOSD61 – JUNE 2017
Figure 61. Pulse Response of the LMC6482-MIL Circuit in Figure 60
8.2.1.2.1.1 Capacitive Load Tolerance
The LMC6482-MIL can typically directly drive a 100-pF load with V_S = 15 V at unity gain without oscillating. The
unity gain follower is the most sensitive configuration. Direct capacitive loading reduces the phase margin of op-
amps. The combination of the output impedance of the op-amp and the capacitive load induces phase lag. This
results in either an underdamped pulse response or oscillation.
Improved frequency response is achieved by indirectly driving capacitive loads, as shown in Figure 62.
Compensated to handle a 330pF capacitive load.
Figure 62. LMC6482-MIL Noninverting Amplifier
R1 and C1 serve to counteract the loss of phase margin by feeding forward the high-frequency component of the
output signal back to the amplifiers inverting input, thereby preserving phase margin in the overall feedback loop.
The values of R1 and C1 are experimentally determined for the desired pulse response. The resulting pulse
response is shown in Figure 63.
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