Datasheet

LTC6252/LTC6253/LTC6254
16
625234fc
Figure 3. 5V Single Supply 16-Bit ADC Driver
TYPICAL APPLICATIONS
5V Single-Supply 16-Bit ADC Driver
Figure 3 shows the LTC6253 driving an LTC2393-16 16-bit
A/D converter on a single 5V supply. The low wideband
noise of the LTC6253 helps to achieve better than 93dB
SNR. A gain of 1.17V/V is taken in the first amplifier, giv-
ing an input voltage range of 3.5V
P-P
for a full-scale input
to the ADC. By taking a small amount of gain, a –1dBFS
Figure 4. LTC6253 Driving LTC2393-16
16b ADC 5V Single-Supply Performance
5V
0.1µF10µF
5V
5V
~2.08V
0.1µF10µF
SER/PAR
BYTESWAP
OB/2C
CS
RD
BUSY
PARALLEL
OR
SERIAL
INTERFACE
OGND
625234 F03
IN
–
IN
+
3900pF
249Ω
249Ω
100Ω
100Ω
V
IN
27.4mV TO
(3.5V + 27.4mV)
GNDRESETCNVST PD
SAMPLE CLOCK
REFOUTREFIN
AVP DVP
LTC2393-16
OVP
1.8V TO 5V
16 BIT
VCM
1µF10µF
2.5k2.5k143Ω
845Ω
4.7µF
–
+
½ LTC6253
5V
–
+
½ LTC6253
FREQUENCY (kHz)
0
AMPLITUDE (dBFS)
0
–80
–20
–40
–60
–100
–120
–140
–160
200 400100 300
624678 F04
500
f
S
= 1Msps
F1 = 20.111kHz
F1 AMPLITUDE
= –1.032dBFS
SNR = 93.28dB
THD = –100.50dB
SINAD = 92.53dB
SFDR = 104.7dB
F2 = –106.39dBc
F3 = –104.70dBc
F4 = –114.13dBc
F5 = –105.48dBc
output can be easily obtained without the amplifier transi-
tioning between input regions, thus minimizing crossover
distortion. Furthermore, by driving VCM with 2.08V from
the ADC’s VCM pin, the LTC6253 is capable of driving the
LTC2393-16 to within 0.1dB of full scale. Figure 4 shows
an FFT obtained with a sampling rate of 1Msps and a
20kHz input waveform. Spurious free dynamic range is
an excellent 104.7dB.