LTC6400CUD-8-PBF LINER [Linear Technology], LTC6400CUD-8-PBF Datasheet - Page 12

• Manufacturer Part Number: LTC6400CUD-8-PBF
• Description: 2.2GHz Low Noise, Low Distortion Differential ADC Driver for DC-300MHz
• Manufacturer: LINER [Linear Technology]

APPLICATIONS INFORMATION
LTC6400-8
Figure 8 summarizes the IMD3 performance of the whole
system as shown in Figure 7.
Test Circuits
Due to the fully-differential design of the LTC6400 and
its usefulness in applications with differing characteristic
specifi cations, two test circuits are used to generate the
information in this datasheet. Test Circuit A is DC987B,
a two-port demonstration circuit for the LTC6400 family.
The silkscreen is shown in Figure 9. This circuit includes
input and output transformers (baluns) for single-ended-
to-differential conversion and impedance transformation,
allowing direct hook-up to a 2-port network analyzer.
There are also series resistors at the output to present
the LTC6400 with a 375Ω differential load, optimizing
distortion performance. Due to the input and output trans-
formers, the –3dB bandwidth is reduced from 2.2GHz to
approximately 1.46GHz.
12
Figure 8. IMD3 for the Combination of LTC6400-8 and LTC2208
–100
–110
–40
–50
–60
–70
–80
–90
0
SINGLE-ENDED INPUT
F
DRIVER V
S
= 122.8Msps
50
OUT
FREQUENCY (MHz)
100
= 2V
P-P
150
COMPOSITE
200
250
64008 F08
300
Test Circuit B uses a 4-port network analyzer to measure
S-parameters and gain/phase response. This removes the
effects of the wideband baluns and associated circuitry,
for a true picture of the >1GHz S-parameters and AC
characteristics.
Figure 9. Top Silkscreen for DC987B. Test Circuit A
64008f