Datasheet
19
LTC1608
Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no represen-
tation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
Figure 22. Intermodulation Distortion Plot
FREQUENCY (kHz)
0
–40
–20
0
200
1608 F22
–60
–80
50 100 150 250
–100
–120
–140
AMPLITUDE (dB)
f
SAMPLE
= 500kHz
f
IN1
= 96.56kHz
f
IN2
= 99.98kHz
(fa ± fb). If the two input sine waves are equal in
magni
tude, the value (in decibels) of the 2nd order IMD
products can be expressed by the following formula:
IMD fa fb Log
Amplitude
±
()
=
±
20
at (fa fb)
Amplitude at fa
Peak Harmonic or Spurious Noise
The peak harmonic or spurious noise is the largest spec-
tral component excluding the input signal and DC. This
value is expressed in decibels relative to the RMS value of
a full-scale input signal.
Full-Power and Full-Linear Bandwidth
The full-power bandwidth is that input frequency at which
the amplitude of the reconstructed fundamental is
reduced by 3dB for a full-scale input signal.
The full-linear bandwidth is the input frequency at which
the S/(N + D) has dropped to 84dB (13.66 effective bits).
The LTC1608 has been designed to optimize input band-
width, allowing the ADC to undersample input signals with
frequencies above the converter’s Nyquist Frequency. The
noise floor stays very low at high frequencies; S/(N + D)
becomes dominated by distortion at frequencies far
beyond Nyquist.
APPLICATIO S I FOR ATIO
WUUU
INPUT FREQUENCY (Hz)
0
–10
–20
–30
–40
–50
–60
–70
–80
–90
–100
–110
AMPLITUDE (dB BELOW THE FUNDAMENTAL)
1608 F21
1k
10k
100k 1M
THD
3RD
2ND
Figure 21. Distortion vs Input Frequency
U
PACKAGE DESCRIPTIO
G Package
36-Lead Plastic SSOP (5.3mm)
(Reference LTC DWG # 05-08-1640)
G36 SSOP 0501
.13 – .22
(.005 – .009)
0
° – 8°
.55 – .95
(.022 – .037)
5.20 – 5.38**
(.205 – .212)
7.65 – 7.90
(.301 – .311)
1234
5
6
7
8 9 10 11 12 14 15 16 17 1813
12.67 – 12.93*
(.499 – .509)
2526 22 21 20 19232427282930313233343536
1.73 – 1.99
(.068 – .078)
.05 – .21
(.002 – .008)
.65
(.0256)
BSC
.25 – .38
(.010 – .015)
MILLIMETERS
(INCHES)
DIMENSIONS DO NOT INCLUDE MOLD FLASH. MOLD FLASH
SHALL NOT EXCEED .152mm (.006") PER SIDE
DIMENSIONS DO NOT INCLUDE INTERLEAD FLASH. INTERLEAD
FLASH SHALL NOT EXCEED .254mm (.010") PER SIDE
*
**
NOTE:
1. CONTROLLING DIMENSION: MILLIMETERS
2. DIMENSIONS ARE IN
3. DRAWING NOT TO SCALE