AD9203-EB datasheet(16/19 Pages) AD

16 / 19 page

REV. 0

AD9203

–16–

ULTRASOUND APPLICATIONS

The AD9203 provides excellent performance in 10-bit ultra-

sound applications. This is demonstrated by its high SNR with

analog input frequencies up to and including Nyquist. The

presence of spurs near the base of a fundamental frequency bin

is demonstrated by Figure 35. Note that the spurs near the noise

floor are more than 80 dB below fIN. This is especially valuable

in Doppler ultrasound applications where low frequency shifts

from the fundamental are important.

AD8138

+3V

AINP

AINN

AD9203

1.5V

+3V

SINGLE-

ENDED

ANALOG

AD604

TGC

AMPLIFIER

ANALOG

INPUT

GAIN

CONTROL

CONDITIONED

TRANSDUCER

SIGNAL

Figure 34. Ultrasound Connection for the AD9203

Figure 34 illustrates the AD604 variable gain amplifier con-

figured for time gain compensation (TGC). The low power

AD9203 is powered from a 3 V supply rail while the high per-

formance AD604 is powered from 5 V supply rails. An AD8138

is used to drive the AD9203. This is implemented due to the

ability of differential drive techniques to cancel common mode

noise and input anomalies.

The 74 mW power consumption gives the 40 MSPS AD9203

an order of magnitude improvement over older generation

components.

FIN

–10

–20

–30

–40

–50

–60

–70

–80

–90

–100

–110

4.5E+6

4.7E+6

4.9E+6

5.1E+6

5.3E+6

5.5E+6

FUND

SNR = 59.9dB

THD = –75dB

SFDR = 82dB

Figure 35. SFDR Performance Near the Fundamental

Signal (8192 Point FFT, fIN = 5 MHz, FS = 40 MSPS)

EVALUATION BOARD

The AD9203 evaluation board is shipped wired for 2 V differen-

tial operation. The board should be connected to power and test

equipment as shown in Figure 36. It is easily configured for

single ended and differential operation as well as 1 V and 2 V

spans. Refer to schematic on next page.

DSP

EQUIPMENT

ANTI-

ALIASING

FILTER

SYNTHESIZER

1MHz 1.9V p-p

HP8644

SYNTHESIZER

40MHz 1V p-p

HP8644

DRVDD

GND

+3-5d

AVDD

GND

AVEE

ANALOG

INPUT

EXTERNAL

CLOCK

AD9203

EVALUATION BOARD

OUTPUT

WORD

+–

+3V

–+

+3V

+–

+3V

+–

Figure 36. Evaluation Board Connection

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