AD7873
Data Sheet
0
Figure 23 shows the power supply rejection ratio vs. VDD supply
frequency for the AD7873. 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 100 mV sine wave applied to the
ADC VCC supply of frequency fS
V
= 3V
CC
100mV p-p SINE WAVE ON +V
CC
–20
–40
V
= 2.5V EXT REFERENCE
REF
fSAMPLE = 125kHz, fIN = 20kHz
PSSR (dB) = 10log(Pf/Pfs)
–60
where:
–80
Pf is power at frequency, f, in ADC output.
Pfs is power at frequency, fs, coupled onto the ADC VCC supply.
–100
–120
Here a 100 mV p-p sine wave is coupled onto the VCC supply.
Decoupling capacitors of 10 µF and 0.1 µF were used on the supply.
0
10
20
30
CC
40
50
60
70
80
90
100
V
RIPPLE FREQUENCY (kHz)
Figure 23. AC PSRR vs. Supply Ripple Frequency
Rev. F | Page 12 of 28
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