ADCMP608

Rev. 0 | Page 8 of 12

Q OUTPUT

INPUT VOLTAGE

500mV OVERDRIVE

10mV OVERDRIVE

DISPERSION

CROSSOVER BIAS POINT

Rail-to-rail inputs of this type, in both op amps and comparators,

have a dual front-end design. Certain devices are active near the

mined point in the common-mode range, a crossover occurs. At

and there are changes in measured offset voltages and currents.

The ADCMP608 slightly elaborates on this scheme. Crossover

points can be found at approximately 0.8 V and 1.6 V.

Figure 10. Propagation Delay—Overdrive Dispersion

MINIMUM INPUT SLEW RATE REQUIREMENT

With the rated load capacitance and normal good PC board

design practice, as discussed in the

Q OUTPUT

INPUT VOLTAGE

10V/ns

1V/ns

DISPERSION

Optimizing Performance

section, these comparators should be stable at any input slew

rate with no hysteresis. Broadband noise from the input stage is

observed in place of the violent chattering seen with most other

high speed comparators. With additional capacitive loading or

poor bypassing, oscillation may be encountered. These oscilla-

tions are due to the high gain bandwidth of the comparator in

combination with feedback through parasitics in the package

and PC board. In many applications, chattering is not harmful.

Figure 11. Propagation Delay—Slew Rate Dispersion