AD9203_15 Datasheet, PDF (19/28 Pages) Analog Devices – 10-Bit, 40 MSPS, 3 V, 74 mW A/D Converter

ULTRASOUND APPLICATIONS
The AD9203 provides excellent performance in 10-bit
ultrasound 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 37. 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.
CONDITIONED
TRANSDUCER
SIGNAL
ANALOG
INPUT
AD604
TGC
AMPLIFIER
GAIN
CONTROL
SINGLE-
ENDED
3V
ANALOG
AD8138
AD9203
AINP
AINN
1.5V
3V
Figure 36. Ultrasound Connection for the AD9203
Figure 36 illustrates the AD604 variable gain amplifier
configured for time gain compensation (TGC). The low power
AD9203
AD9203 is powered from a 3 V supply rail while the high
performance 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.
10
0
–10
–20
–30
–40
–50
–60
–70
–80
–90
–100
–110
4.5E+6
4.7E+6
FUND
SNR = 59.9dB
THD = –75dB
SFDR = 82dB
4.9E+6
5.1E+6
f_IN
5.3E+6
5.5E+6
Figure 37. SFDR Performance Near the Fundamental Signal (8192 Point FFT,
fIN = 5 MHz, FS = 40 MSPS)
Rev. B | Page 19 of 28