Rainbow Electronics ADC14061 - Manual (Page 19)

Applications Information
(Continued)
put alternates between 12 pF and 28 pF, depending upon the
phase of the clock. This dynamic loaad is more difficult to
drive than is a fixed capacitance.
If the amplifier exhibits overshoot, ringing, or any evidence of
instability, even at a very low level, it will degrade perfor-
mance. Amplifiers that have been used sucessfully to dirve
the analog inputs of the ADC14061 include the CLC427,
CLC440, LM6152, LM6154, LM6181 and the LM6182. A
small series reistor at each amplifier output and a capacitor
across the analog inputs (as shown in
Figure 7 ) will often im-
prove performance.
Operating with the reference pins outside of the speci-
fied range. As mentioned in section 1.2, V
REF
should be in
the range of
1.8V ≤ V
REF
≤ 2.2V
with V
REF
−
IN
≤
1.0V. Operating outside of these limits could
lead to signal distortion.
Using a clock source with excessive jitter, using exces-
sively long clock signal trace, or having other signals
coupled to the clock signal trace. This will cause the sam-
pling interval to vary, causing excessive output noise and a
reduction in SNR performance.
Connecting pins marked ″ NC ″ to any potential. Some of
these pins are used for factory testing. They should all be left
floating. Connecting them to ground, power supply, or some
other voltage could result in a non-functional device.
www.national.com 19