AD7490 datasheet(9/29 Pages) AD

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AD7490

Data Sheet

Rev. D | Page 8 of 28

TYPICAL PERFORMANCE CHARACTERISTICS

Figure 5 shows a typical FFT plot for the AD7490 at 1 MSPS sample rate and 50 kHz input frequency.

Figure 7 shows the power supply rejection ratio vs. supply ripple frequency for the AD7490. 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 VDD supply

of frequency fS.

( )













PSRR

log

where:

Pf is equal to the power at frequency f in ADC output.

PfS is equal to power at frequency fS coupled onto the ADC VDD supply input.

Here, a 200 mV p-p sine wave is coupled onto the VDD supply. 10 nF decoupling was used on the supply, and a 1 µF decoupling capacitor

was used on the REFIN pin.

–95

–75

–55

–35

–15

100

150

200

250

300

350

400

500

450

8192 POINT FFT

fSAMPLE = 1MSPS

fIN = 50kHZ

SINAD = 70.697dB

THD = –79.171dB

SFDR = –79.93dB

FREQUENCY (kHz)

Figure 5. Dynamic Performance at 1 MSPS

100

1000

INPUT FREQUENCY (kHz)

fS = MAX THROUGHPUT

TA = 25°C

RANGE = 0V TO REFIN

VDD = VDRIVE = 5.25V

VDD = VDRIVE = 4.75V

VDD = VDRIVE = 3.6V

VDD = VDRIVE = 2.7V

Figure 6. SINAD vs. Analog Input Frequency

for Various Supply Voltages at 1 MSPS

–20

–90

–80

–70

–60

–50

–40

–30

100k 200k 300k 400k 500k 600k 700k 800k 900k

INPUT FREQUENCY (Hz)

VDD = 5V

VDD = 3V

VDD = 3V/5V, 10nF CAP

200mV p-p SINE WAVE ON VDD

REFIN = 2.5V, 1µF CAP

TA = 25°C

Figure 7. PSRR vs. Supply Ripple Frequency

–50

–90

–85

–80

–75

–70

–65

–60

–55

100

1000

INPUT FREQUENCY (kHz)

VDD = VDRIVE = 2.7V

VDD = VDRIVE = 3.6V

VDD = VDRIVE = 4.75V

VDD = VDRIVE = 5.25V

fS = MAX THROUGHPUT

TA = 25°C

RANGE = 0V TO REFIN

Figure 8. THD vs. Analog Input Frequency

for Various Supply Voltages at 1 MSPS

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