Datasheet

5
LTC1409
Note 11: The falling CONVST edge starts a conversion. If CONVST returns
high at a critical point during the conversion it can create small errors. For
best results ensure that CONVST returns high either within 650ns after
conversion start or after BUSY rises.
TI I G CHARACTERISTICS
W
U
Note 12: Signal-to-noise ratio (SNR) is measured at 100kHz and distortion
is measured at 400kHz. These results are used to calculate signal-to-noise
plus distortion (SINAD).
TYPICAL PERFORMANCE CHARACTERISTICS
U
W
S/(N + D) vs Input Frequency
and Amplitude
INPUT FREQUENCY (Hz)
1k
SIGNAL/(NOISE + DISTORTION) (dB)
80
70
60
50
40
30
20
10
0
10k 100k
LTC1409 • TPC01
1M 10M
V
IN
= 0dB
V
IN
= 20dB
V
IN
= 60dB
INPUT FREQUENCY (Hz)
1k
SIGNAL/(NOISE + DISTORTION) (dB)
80
70
60
50
40
30
20
10
0
10k 100k
LTC1409 • TPC02
1M 10M
Signal-to-Noise Ratio vs
Input Frequency
Spurious-Free Dynamic Range vs
Input Frequency
INPUT FREQUENCY (Hz)
10k
SPURIOUS-FREE DYNAMIC RANGE (dB)
0
–10
–20
–30
–40
–50
–60
–70
–80
–90
–100
100k 1M 10M
LTC1409 • TPC04
Distortion vs Input Frequency
INPUT FREQUENCY (Hz)
AMPLITUDE (dB BELOW THE FUNDAMENTAL)
0
–10
–20
–30
–40
–50
–60
–70
–80
–90
–100
1k 100k 1M 10M
LTC1409 • TPC03
10k
THD
3RD
2ND
Intermodulation Distortion Plot
FREQUENCY (Hz)
0
AMPLITUDE (dB)
0

–20

–40

–60

–80

–100

–120
100k 200k 300k 400k
LTC1409 • TPC05
50k 150k 250k 350k
fb – fa
2fb – fa
2fa – fb
2fa
2fb
3fb
fa + 2fb
3fa
2fa + fb

f
SAMPLE
= 800kHz
f
IN1
= 88.19580078kHz
f
IN2
= 111.9995117kHz
fa + fb