Datasheet

LTC2389-16
24
238916f
applications inFormation
An alternate single-ended to differential topology em-
ploying the LT6231 followed by the LT6201 is shown in
Figure8a. This topology enables additional band-limiting
of the wideband noise of the single-ended to differential
conversion circuit using lowpass filters A without affect-
ing the settling at the inputs of the LTC2389-16 during
acquisition. This circuit achieves the full ADC data sheet
SNR specifications, as shown in the FFT plot in Figure 8b.
Figure 8b. 32k Point FFT f
SMPL
= 2.5Msps, f
IN
= 2kHz,
for Circuit Shown in Figure 8a
Figure 8a. LT6231 Converting a 0V to 4.096V Single-Ended Signal to a ±4.096V
Fully-Differential Signal Followed by LT6201 Buffering Fully-Differential Signal
238916 F08a
IN
–
IN
+
1nF
10Ω
10Ω
1/2 LT6201
LOWPASS FILTERS B
1/2 LT6201
LTC2389-16
1nF
+
–
+
–
10nF
50Ω
50Ω
LOWPASS FILTERS A
10nF
+
–
+
–
1k1k
1/2 LT6231
1/2 LT6231
+
–
4.096V
0V
4.096V
0V
4.096V
0V
V
CM
= 2.048V
49.9Ω
49.9Ω
FREQUENCY (kHz)
0
AMPLITUDE (dBFS)
–60
–40
–20
–80
–100
500250 750 1000 1250
–160
–180
–120
0
–140
238916 F08b
SNR = 96.0dB
THD = –116dB
SINAD = 96.0dB
SFDR = 117dB