V

to minimize noise.

V

be bypassed to a clean, quiet point in the analog ground

plane with a 0.1 µF capacitor. DO NOT allow this pin to float.

2.0 THE ANALOG INPUT

The analog input of the ADC08060 is a switch followed by an

integrator. The input capacitance changes with the clock

level, appearing as 3 pF when the clock is low, and 4 pF

when the clock is high. Since a dynamic capacitance is more

difficult to drive than is a fixed capacitance, choose an

amplifier that can drive this type of load. The LMH6702 has

been found to be a good amplifier to drive the ADC08060.

Figure 4 shows an example of an input circuit using the

LMH6702. Any input amplifier should incorporate some gain

as operational amplifiers exhibit better phase margin and

transient response with gains above 2 or 3 than with unity

gain. If an overall gain of less than 3 is required, attenuate

the input and operate the amplifier at a higher gain, as

shown in Figure 4.

20006233

FIGURE 3. Driving the reference to force desired values requires driving with a low impedance source.

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