LTC6417 Datasheet, PDF (1/32 Pages) Linear Technology – 1.6GHz Low Noise High Linearity Differential Buffer/ 16-Bit ADC Driver with Fast Clamp

LTC6417
Features
n _{1.6GHz –3dB Small Signal Bandwidth}
n _{Low Distortion Driving 50Ω Load, 2.4VP-P Out}
–100dBc/–69dBc HD2/HD3 at 140MHz
–80dBc IM3 and 46dBm OIP3 at 140MHz
–100dBc/–66dBc HD2/HD3 at 380MHz
–68dBc IM3 and 39dBm OIP3 at 380MHz
n _{1.5nV/√Hz Output Noise}
n _{4.3pA/√Hz Input Current Noise}
n _{Programmable High Speed, Fast Recovery}
Output Clamping
n _{4.28VP-P Maximum Output Swing on a 50Ω}
Differential Load
n _{DC-Coupled Signal Path}
n _{Operates on Single 4.75V to 5.25V Supply}
n _{Power: 615mW on 5V, Can Be Reduced to 370mW,}
Shutdown Mode 120mW
n _{3mm × 4mm 20-Lead QFN Package}
Applications
n _{Differential ADC Driver}
n _{CCD Buffer}
n _{Cable Driver}
n _{50Ω Buffer}
L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear
Technology Corporation. All other trademarks are the property of their respective owners.
1.6GHz Low Noise High Linearity
Differential Buffer/16-Bit ADC
Driver with Fast Clamp
Description
The LTC^®6417 is a differential unity gain buffer that can
drive a 50Ω load with extremely low noise and excellent
linearity. It is well suited for driving high speed 14- and
16-bit pipeline ADCs with input signals from DC to beyond
600MHz. Differential input impedance is 18.5kΩ, allowing
1:4 and 1:8 transformers to be used at the input providing
additional system gain in 50Ω systems.
With no external biasing or gain setting components and
a flow-through pinout, the LTC6417 is very easy to use. It
can be DC-coupled and has a common mode output offset
of –60mV. The LTC6417 input pins are internally biased to
provide an output common mode voltage that is set by
the voltage on the V_CM pin for AC-coupled applications.
Supply current is typically 123mA and the LTC6417 operates
on supply voltages ranging from 4.75V to 5.25V. Power
consumption can be reduced to 74mA via the PWRADJ
pin. The LTC6417 also has a hardware shutdown feature
which reduces current consumption to 24mA.
The LTC6417 features fast, adjustable output voltage clamp-
ing to help protect subsequent circuitry. The CLHI pin sets
the maximum swing, while a symmetric minimum swing
is set up internally. LTC6417 V_OR pin will signal overrange
when the clamps limit output voltage.
The LTC6417 is packaged in a 20-lead 3mm × 4mm QFN
package. Pinout is optimized for placement directly adjacent
to Linear Technology’s high speed 14- and 16-bit ADCs.
Typical Application
LTC6417 Driving an LTC2209 16-Bit ADC at 140MHz IF
5V
3.3V
50Ω
+–
680pF
0.1µF
1,6,
11,16
2.2µF
T1
WBC4-14LB
4
3
2
••
6
1
0.01µF
100Ω
100Ω
0.01µF
V^{+ 5}
PWRADJ ²
8 _IN+
CLHI
19
OUT⁺
9
LTC6417
IN^–
OUT
V_CM^VOR
–
18
SHDN
14
GND ₁₂ 15 _1k
3, 7,10,
17, 20, 21
C43
27pF
E1
51nH
R36
60.4Ω
C41
12pF
R12
60.4Ω
C44
27pF
E2
51nH
2.2µF
E3
75nH
C45
18pF
E5
51nH
R42
300Ω
10Ω
C40
12pF
R53
120Ω
C10
R43
12pF 300Ω
10Ω
E3
75nH
C46
18pF
A_IN+
16
LTC2209
A_IN–
V_CM PGA = 0
CLOCK
(153.6MHz)
6417 TA01a
LTC6417 Driving LTC2209
16-Bit ADC 32K Point FFT,
f_IN = 140MHz, –1dBFS, PGA = 0
0
–10
–20
–30
–40
–50
–60
–70
–80
–90
–100
–110
–120
0
HD2 = –88dBc
HD3 = –94dBc
SFDR = 88dBc
SNR = 75.4dB
SEE FIGURE 1/TABLE 1
1:4 BALUN
f_S = 153.6Msps
DEMO BOARD DC1685A
10 20 30 40 50 60 70 80
FREQUENCY (MHz)
6417 TA01b
6417f
1