Datasheet

AD7609 Data Sheet
Rev. A | Page 20 of 36
Power Supply Rejection (PSR)
Variations in power supply affect the full-scale transition but
not the converter’s linearity. Power supply rejection is the
maximum change in full-scale transition point due to a change
in power supply voltage from the nominal value. The power
supply rejection ratio is defined as the ratio of the power in
the ADC output at full-scale frequency, f, to the power of a
200 mV p-p sine wave applied to the ADC V
DD
and V
SS
supplies
of Frequency f
S
.
PSRR (dB) = 10 log (Pf/Pf
S
)
where:
Pf is equal to the power at Frequency f in the ADC output.
Pf
S
is equal to the power at Frequency f
S
coupled onto the V
DD
and V
SS
supplies.
Channel-to-Channel Isolation
Channel-to-channel isolation is a measure of the level of crosstalk
between any two channels. It is measured by applying a full-scale,
10 kHz sine wave signal to all unselected input channels and
determining the degree to which the signal attenuates in the
selected channel with a 1 kHz signal.
Common-Mode Rejection Ratio (CMRR)
CMRR is defined as the ratio of the power in the ADC
common-mode input at full-scale frequency, f, to the power in
the output of a full-scale p-p sine wave applied to the common-
mode voltage of V
IN
X+ and V
IN
X− of frequency, f
S
,
CMRR (dB) = 20 log (Pf/Pf
S
)
where:
Pf is equal to the power at Frequency f in the ADC input.
Pf
S
is equal to the power at Frequency f
S
in the ADC output.