FEATURES
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LT6402-20
300MHz Low Distortion, Low
Noise Differential Amplifier/
ADC Driver (A
V
= 20dB)
DESCRIPTIO
The LT
®
6402-20 is a low distortion, low noise differential
amplifier/ADC driver for use in applications from DC to
300MHz. The LT6402-20 has been designed for ease of
use, with minimal support circuitry required. Exceptionally
low input-referred noise and low distortion (with either
single-ended or differential inputs) make the LT6402-20
an excellent solution for driving high speed 12-bit and
14-bit ADCs. In addition to the normal unfiltered outputs
(+OUT and –OUT), the LT6402-20 has a built-in 75MHz
differential low pass filter and an additional pair of filtered
outputs (+OUTFILTERED, –OUTFILTERED) to reduce
external filtering components when driving high speed
ADCs. The output common mode voltage is easily set via
the V
OCM
pin, eliminating an output transformer or AC-
coupling capacitors in many applications.
The LT6402-20 is designed to meet the demanding require-
ments of communications transceiver applications. It can
be used as a differential ADC driver, a general-purpose
differential gain block, or in other applications requiring
differential drive. The LT6402-20 can be used in data
acquisition systems required to function at frequencies
down to DC.
The LT6402-20 operates on a 5V supply and consumes
30mA. It comes in a compact 16-lead 3mm
×
3mm QFN pack-
age and operates over a –40°C to 85°C temperature range.
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300 MHz –3dB Bandwidth
Fixed Gain of 20dB
Low Distortion:
51dBm OIP3, –81dBc HD3 (20MHz, 2V
P-P
)
Low Noise:
12.4dB NF, e
n
= 1.9nV/√Hz (20MHz)
Differential Inputs and Outputs
Additional Filtered Outputs
Adjustable Output Common Mode Voltage
DC- or AC-Coupled Operation
Minimal Support Circuitry Required
Small 0.75mm Profile 16-Lead 3mm
×
3mm QFN
Package
APPLICATIO S
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Differential ADC Driver for:
Imaging
Communications
Differential Driver/Receiver
Single Ended to Differential Conversion
Differential to Single Ended Conversion
Level Shifting
IF Sampling Receivers
SAW Filter Interfacing/Buffering
, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
TYPICAL APPLICATIO
5V
0.1µF
Distortion vs Frequency, Differential
Input, No R
LOAD
–40
–50
DISTORTION (dBc)
–60
–70
–80
–90
–100
6402 TA01a
0.1µF
–INB
–INA
0.1µF
0.1µF
IF IN
+INB
+INA
V
EE
V
CC
V
OCM
+OUT
LT6402-20
–OUT
10Ω
10Ω
AIN
+
LTC
®
2249
AIN
–
V
CM
1
U
U
U
FILTERED OUTPUTS
V
OUT
= 2V
P-P
HD3
HD2
10
FREQUENCY (MHz)
100
64022 G08
640220fa
1
LT6402-20
ABSOLUTE
(Note 1)
AXI U RATI GS
PACKAGE/ORDER I FOR ATIO
TOP VIEW
+INA
+INB
–INA
–INB
Total Supply Voltage (V
CCA
/V
CCB
/V
CCC
to
V
EEA
/V
EEB
/V
EEC
) ...................................................5.5V
Input Current (+INA, –INA, +INB, –INB,
V
OCM
, ENABLE)................................................±10mA
Output Current (Continuous)
+OUT, –OUT ...................................................±100mA
+OUTFILTERED, –OUTFILTERED......................±30mA
Output Short Circuit Duration (Note 2) ............ Indefinite
Operating Temperature Range (Note 3) ... –40°C to 85°C
Specified Temperature Range (Note 4) .... –40°C to 85°C
Storage Temperature Range................... –65°C to 125°C
Junction Temperature ........................................... 125°C
Lead Temperature Range (Soldering 10 sec) ........ 300°C
16 15 14 13
V
CCC
1
V
OCM
2
V
CCA
3
V
EEA
4
5
+OUT
6
+OUTFILTERED
7
–OUTFILTERED
8
–OUT
17
12 V
EEC
11 ENABLE
10 V
CCB
9
V
EEB
UD PACKAGE
16-LEAD (3mm
×
3mm) PLASTIC QFN
T
JMAX
= 125°C,
θ
JA
= 68°C/W,
θ
JC
= 4.2°C/W
EXPOSED PAD IS V
EE
(PIN 17)
MUST BE SOLDERED TO THE PCB
ORDER PART NUMBER
LT6402CUD-20
LT6402IUD-20
UD PART MARKING*
LCBC
LCBC
Order Options
Tape and Reel: Add #TR
Lead Free: Add #PBF Lead Free Tape and Reel: Add #TRPBF
Lead Free Part Marking:
http://www.linear.com/leadfree/
Consult LTC Marketing for parts specified with wider operating temperature ranges.
*The temperature grade is identified by a label on the shipping container.
DC ELECTRICAL CHARACTERISTICS
SYMBOL
GDIFF
V
SWINGMIN
V
SWINGMAX
V
SWINGDIFF
I
OUT
V
OS
TCV
OS
Output Voltage Swing
Output Current Drive
Input Offset Voltage
PARAMETER
Gain
CONDITIONS
The
●
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
CCA
= V
CCB
= V
CCC
= 5V, V
EEA
= V
EEB
= V
EEC
= 0V,
⎯
E
⎯
N
⎯
A
⎯
B
⎯
L
⎯
E = 0.8V, +INA
shorted to +INB (+IN), –INA shorted to –INB (–IN), V
OCM
= 2.2V, Input common mode voltage = 2.2V, no R
LOAD
unless otherwise noted.
MIN
●
TYP
20
0.25
MAX
20.9
0.35
0.5
UNITS
dB
V
V
V
V
V
P-P
V
P-P
mA
Input/Output Characteristics (+INA, +INB, –INA, –INB, +OUT, –OUT, +OUTFILTERED, –OUTFILTERED)
Differential (+OUT, –OUT), V
IN
= ±160mV
Differential
Single-Ended +OUT, –OUT, +OUTFILTERED,
–OUTFILTERED, V
IN
= ±600mV Differential
Single-Ended +OUT, –OUT, +OUTFILTERED,
–OUTFILTERED, V
IN
= ±600mV Differential
Differential (+OUT, –OUT), V
IN
= ±600mV
Differential
18.9
●
●
●
●
●
3.4
3.3
6.1
5.6
±30
–6.5
–10
3.6
7
±35
1
2.5
6.5
10
Input Offset Voltage Drift
T
MIN
to T
MAX
●
µV/°C
640220fa
2
U
mV
mV
W
U
U
W W
W
LT6402-20
DC ELECTRICAL CHARACTERISTICS
SYMBOL
I
VRMIN
I
VRMAX
R
INDIFF
C
INDIFF
CMRR
R
OUTDIFF
C
OUTDIFF
GCM
V
OCMMIN
V
OCMMAX
V
OSCM
I
BIASCM
R
INCM
C
INCM
⎯
E
⎯
N
⎯
A
⎯
B
⎯
L
⎯
E Pin
V
IL
V
IH
I
IL
I
IH
Power Supply
V
S
I
S
I
SDISABLED
PSRR
Operating Range
Supply Current
Supply Current (Disabled)
Power Supply Rejection Ratio
⎯
E
⎯
N
⎯
A
⎯
B
⎯
L
⎯
E = 0.8V
⎯
EN
⎯
A
⎯
B
⎯
L
⎯
E = 2V
⎯
4V to 5.5V
●
●
●
●
The
●
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
CCA
= V
CCB
= V
CCC
= 5V, V
EEA
= V
EEB
= V
EEC
= 0V,
⎯
E
⎯
N
⎯
A
⎯
B
⎯
L
⎯
E = 0.8V, +INA
shorted to +INB (+IN), –INA shorted to –INB (–IN), V
OCM
= 2.2V, Input common mode voltage = 2.2V, no R
LOAD
unless otherwise noted.
PARAMETER
Input Voltage Range, MIN
Input Voltage Range, MAX
Input Resistance
Input Capacitance
Common Mode Rejection Ratio
Output Resistance
Output Capacitance
Common Mode Gain
Output Common Mode Voltage
Adjustment Range, MIN
Output Common Mode Voltage
Adjustment Range, MAX
Output Common Mode Offset
Voltage
V
OCM
Input Bias Current
V
OCM
Input Resistance
V
OCM
Input Capacitance
⎯
EN
⎯
A
⎯
B
⎯
L
⎯
E Input Low Voltage
⎯
⎯
EN
⎯
A
⎯
B
⎯
L
⎯
E Input High Voltage
⎯
⎯
E
⎯
N
⎯
A
⎯
B
⎯
L
⎯
E Input Low Current
⎯
EN
⎯
A
⎯
B
⎯
L
⎯
E Input High Current
⎯
⎯
E
⎯
N
⎯
A
⎯
B
⎯
L
⎯
E = 0.8V
⎯
EN
⎯
A
⎯
B
⎯
L
⎯
E = 2V
⎯
●
●
●
●
CONDITIONS
Single-Ended
Single-Ended
●
●
●
MIN
3.9
77
45
TYP
MAX
0.9
UNITS
V
V
Ω
pF
dB
Ω
pF
100
1
70
0.3
0.8
122
Input Common Mode 0.9V to 3.9V
●
Common Mode Voltage Control (V
OCM
Pin)
Differential (+OUT, –OUT), V
OCM
= 1.2V to 3.6V
Differential (+OUT, –OUT), V
OCM
= 1.4V to 3.4V
●
●
0.9
0.9
1
1.1
1.1
1.2
1.4
V/V
V/V
V
V
V
V
Single-Ended
●
3.6
3.4
–30
4
5
0.8
3
1
0.8
2
0.5
1
4
24
55
5
30
250
90
3
5.5
37
500
30
15
Measured from V
OCM
to Average of +OUT and –OUT
●
●
mV
µA
MΩ
pF
V
V
µA
µA
V
mA
µA
dB
640220fa
3
LT6402-20
AC ELECTRICAL CHARACTERISTICS
SYMBOL
–3dBBW
0.1dBBW
0.5dBBW
SR
t
s1%
t
ON
t
OFF
–3dBBW
CM
SR
CM
10MHz Signal
Second/Third Harmonic Distortion
Third-Order IMD
OIP3
10M
NF
e
n10M
20MHz Signal
Second/Third Harmonic Distortion
Third-Order IMD
2V
P-P
Differential (+OUTFILTERED, –OUTFILTERED)
2V
P-P
Differential (+OUT, –OUT)
2V
P-P
Differential Composite (+OUTFILTERED,
–OUTFILTERED), f1 = 19.5MHz, f2 = 20.5MHz
2V
P-P
Differential Composite (+OUT, –OUT),
R
L
= 400Ω, f1 = 19.5MHz, f2 = 20.5MHz
OIP3
20M
NF
e
n20M
Output Third-Order Intercept
Noise Figure
Input Referred Noise Voltage Density
1dB Compression Point
R
L
= 100Ω (Note 5)
Differential (+OUTFILTERED, –OUTFILTERED),
f1 = 19.5MHz, f2 = 20.5MHz (Note 5)
Measured Using DC954A Demo Board
–81
–81
–96
–91
51
12.4
1.9
18
dBc
dBc
dBc
dBc
dBm
dB
nV/√Hz
dBm
Output Third-Order Intercept
Noise Figure
Input Referred Noise Voltage Density
1dB Compression Point
R
L
= 100Ω (Note 5)
2V
P-P
Differential (+OUTFILTERED, –OUTFILTERED)
2V
P-P
Differential (+OUT, –OUT)
2V
P-P
Differential Composite (+OUTFILTERED,
–OUTFILTERED), f1 = 9.5MHz, f2 = 10.5MHz
Differential (+OUTFILTERED, –OUTFILTERED),
f1 = 9.5MHz, f2 = 10.5MHz (Note 5)
Measured Using DC954A Demo Board
–85
–85
–93
49.5
12.3
1.85
19.5
dBc
dBc
dBc
dBm
dB
nV/√Hz
dBm
PARAMETER
–3dB Bandwidth
Bandwidth for 0.1dB Flatness
Bandwidth for 0.5dB Flatness
Slew Rate
1% Settling
Turn-On Time
Turn-Off Time
Common Mode Small-Signal –3dB
Bandwidth
Common Mode Slew Rate
0.1V
P-P
at V
OCM
, Measured Single-Ended at +OUT
and –OUT
1.3V to 3.4V Step at V
OCM
Input/Output Characteristics
20mV
P-P
Differential (+OUT, –OUT)
20mV
P-P
Differential (+OUT, –OUT)
20mV
P-P
Differential (+OUT, –OUT)
3.2V
P-P
Differential (+OUT, –OUT)
1% Settling for a 1V
P-P
Differential Step
(+OUT, –OUT)
200
300
30
80
400
8
100
1
200
250
MHz
MHz
MHz
V/µs
ns
ns
µs
MHz
V/µs
T
A
= 25°C, V
CCA
= V
CCB
= V
CCC
= 5V, V
EEA
= V
EEB
= V
EEC
= 0V,
⎯
E
⎯
N
⎯
A
⎯
B
⎯
L
⎯
E = 0.8V, +INA shorted to +INB (+IN), –INA shorted to –INB (–IN), V
OCM
= 2.2V, Input common mode voltage = 2.2V, no R
LOAD
unless otherwise noted.
CONDITIONS
MIN
TYP
MAX
UNITS
Common Mode Voltage Control (V
OCM
Pin)
Noise/Harmonic Performance Input/Output Characteristics
640220fa
4
LT6402-20
AC ELECTRICAL CHARACTERISTICS
SYMBOL
25MHz Signal
Second/Third Harmonic Distortion
Third-Order IMD
2V
P-P
Differential (+OUTFILTERED, –OUTFILTERED)
2V
P-P
Differential (+OUT, –OUT)
2V
P-P
Differential Composite (+OUTFILTERED,
–OUTFILTERED), f1 = 24.5MHz, f2 = 25.5MHz
2V
P-P
Differential Composite (+OUT, –OUT),
R
L
= 400Ω, f1 = 24.5MHz, f2 = 25.5MHz
OIP3
25M
NF
e
n25M
Output Third-Order Intercept
Noise Figure
Input Referred Noise Voltage Density
1dB Compression Point
R
L
= 100Ω (Note 5)
Differential (+OUTFILTERED, –OUTFILTERED),
f1 = 24.5MHz, f2 = 25.5MHz (Note 5)
Measured Using DC954A Demo Board
–80
–80
–86
–84
46
12.5
1.9
16.6
dBc
dBc
dBc
dBc
dBm
dB
nV/√Hz
dBm
PARAMETER
T
A
= 25°C, V
CCA
= V
CCB
= V
CCC
= 5V,V
EEA
= V
EEB
= V
EEC
= 0V,
⎯
E
⎯
N
⎯
A
⎯
B
⎯
L
⎯
E = 0.8V, +INA shorted to +INB (+IN), –INA shorted to –INB (–IN), V
OCM
= 2.2V, Input common mode voltage = 2.2V, no R
LOAD
unless otherwise noted.
CONDITIONS
MIN
TYP
MAX
UNITS
Note 1:
Stresses beyond those listed under Absolute Maximum Ratings
may cause permanent damage to the device. Exposure to any Absolute
Maximum Rating condition for extended periods may affect device
reliability and lifetime.
Note 2:
As long as output current and junction temperature are kept below
the Absolute Maximum Ratings, no damage to the part will occur.
Note 3:
The LT6402 is guaranteed functional over the operating
temperature range of –40°C to 85°C.
Note 4:
The LT6402C is guaranteed to meet specified performance from
0°C to 70°C. It is designed, characterized and expected to meet specified
performance from –40°C and 85°C but is not tested or QA sampled
at these temperatures. The LT6402I is guaranteed to meet specified
performance from –40°C to 85°C.
Note 5:
Since the LT6402-20 is a feedback amplifier with low output
impedance, a resistive load is not required when driving an ADC.
Therefore, typical output power is very small. In order to compare the
LT6402-20 with typical g
m
amplifiers that require 50Ω output loading, the
LT6402-20 output voltage swing driving an ADC is converted to OIP3 and
P1dB as if it were driving a 50Ω load.
TYPICAL PERFORMANCE CHARACTERISTICS
Frequency Response
R
LOAD
= 400Ω
30
25
20
GAIN (dB)
15
10
5
V
IN
= 20mV
P-P
UNFILTERED: R
LOAD
= 400Ω
–5
FILTERED: R
LOAD
= 300Ω (EXTERNAL)
+ 100Ω (INTERNAL, FILTERED OUTPUTS)
–10
10
100
1000
1
FREQUENCY (MHz)
64022 G01
Frequency Response vs
C
LOAD
, R
LOAD
= 400Ω
35
30
V
IN
= 20mV
P-P
UNFILTERED OUTPUTS
30
25
20
GAIN (dB)
15
Frequency Response
R
LOAD
= 100Ω
UNFILTERED
25
GAIN (dB)
FILTERED
20
15
10
5
0
1
0pF
1.6pF
5pF
10pF
10
100
FREQUENCY (MHz)
1000
34022 G02
UNFILTERED
FILTERED
10
5
V
IN
= 20mV
P-P
UNFILTERED: R
LOAD
= 100Ω
–5
FILTERED: R
LOAD
= 100Ω
(INTERNAL, FILTERED OUTPUTS)
–10
10
100
1
FREQUENCY (MHz)
0
0
1000
64022 G03
640220fa
5
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