geted at processing signals from DC to 300MHz. The part
has been specifically designed to drive 12-, 14- and 16-bit
ADCs with low noise and low distortion, but can also be
used as a general-purpose broadband gain block.
The LTC6400-8 is easy to use, with minimal support cir-
cuitry required. The output common mode voltage is set
using an external pin, independent of the inputs, which
eliminates the need for transformers or AC-coupling ca-
pacitors in many applications. The gain is internally fixed
at 8dB (2.5V/V).
The LTC6400-8 saves space and power compared to al-
ternative solutions using IF gain blocks and transformers.
The LTC6400-8 is packaged in a compact 16-lead 3mm
×
3mm QFN package and operates over the –40°C to 85°C
temperature range.
L,
LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
2.2GHz –3dB Bandwidth
Fixed Gain of 2.5V/V (8dB)
–99dBc IMD3 at 70MHz (Equivalent OIP3 = 53.4dBm)
–61dBc IMD3 at 300MHz (Equivalent OIP3 = 34.8dBm)
1nV/√Hz Internal Op Amp Noise
7.6dB Noise Figure
Differential Inputs and Outputs
400Ω Input Impedance
2.85V to 3.5V Supply Voltage
85mA Supply Current (255mW)
1V to 1.6V Output Common Mode, Adjustable
DC- or AC-Coupled Operation
Max Differential Output Swing 4.8V
P-P
Small 16-Lead 3mm
×
3mm
×
0.75mm QFN Package
APPLICATIONS
n
n
n
n
n
Differential ADC Driver
Differential Driver/Receiver
Single Ended to Differential Conversion
IF Sampling Receivers
SAW Filter Interfacing
TYPICAL APPLICATION
3.3V
3.3V
70
C2
0.1μF
C1
1000pF
C3
0.1μF
V
IN
R1
59.0Ω
C4
0.1μF
–IN
R2
27.4Ω
V–
1.25V
C5
0.1μF
R3
100Ω
V
+
+IN
+OUT
LTC6400-8
–OUT
V
OCM
L1
R
S2
24nH
15Ω
COILCRAFT
0603CS
C
F1
33pF R
S4
10Ω
C
F3
33pF
R
S1
15Ω
C
F2
33pF
OUTPUT IP3 (dBm)
R
S3
10Ω
60
50
40
30
20
10
64008 TA01a
Equivalent Output IP3 vs Frequency
(NOTE 7)
AIN
+
V
DD
LTC2208
AIN
–
V
CM
LTC2208
130Msps
16-Bit ADC
0
0
50
100
150
200
FREQUENCY (MHz)
250
300
64008 TA01b
64008f
1
LTC6400-8
ABSOLUTE MAXIMUM RATINGS
(Note 1)
PIN CONFIGURATION
TOP VIEW
–IN
–IN
+IN
+IN
12 V
–
17
11
ENABLE
10 V
+
9 V
–
5
–OUT
6
–OUTF
7
+OUTF
8
+OUT
16 15 14 13
V
+
1
Supply Voltage (V
CC
– V
EE
) ......................................3.6V
Input Current (Note 2)..........................................±10mA
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 150°C
Maximum Junction Temperature........................... 150°C
V
OCM
2
V
+
3
V
–
4
UD PACKAGE
16-LEAD (3mm 3mm) PLASTIC QFN
T
JMAX
= 150°C,
θ
JA
= 68°C/W,
θ
JC
= 7.5°C/W
EXPOSED PAD (PIN 17) IS V
–
, MUST BE SOLDERED TO PCB
ORDER INFORMATION
LEAD FREE FINISH
LTC6400CUD-8#PBF
LTC6400IUD-8#PBF
TAPE AND REEL
LTC6400CUD-8#TRPBF
LTC6400IUD-8#TRPBF
PART MARKING*
LCCQ
LCCQ
PACKAGE DESCRIPTION
SPECIFIED TEMPERATURE RANGE
16-Lead (3mm
×
3mm) Plastic QFN 0°C to 70°C
16-Lead (3mm
×
3mm) Plastic QFN –40°C to 85°C
Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container.
Consult LTC Marketing for information on non-standard lead based finish parts.
For more information on lead free part marking, go to:
http://www.linear.com/leadfree/
For more information on tape and reel specifications, go to:
http://www.linear.com/tapeandreel/
LTC6400 AND LTC6401 SELECTOR GUIDE
PART NUMBER
LTC6401-8
LTC6401-14
LTC6401-20
LTC6401-26
LTC6400-8
LTC6400-14
LTC6400-20
LTC6400-26
GAIN
(dB)
8
14
20
26
8
14
20
26
GAIN
(V/V)
2.5
5
10
20
2.5
5
10
20
Please check each datasheet for complete details.
Z
IN
(DIFFERENTIAL)
(Ω)
400
200
200
50
400
200
200
50
I
CC
(mA)
45
45
50
45
85
85
90
85
In addition to the LTC6400 family of amplifiers, a lower power LTC6401 family is available. The LTC6401 is pin compatible to the LTC6400, and has the
same low noise performance. The lower power consumption of the LTC6401 comes at the expense of slightly higher non-linearity, especially at input
frequencies above 140MHz. Please refer to the separate LTC6401 data sheets for complete details.
64008f
2
LTC6400-8
DC ELECTRICAL CHARACTERISTICS
+
The
l
–
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V = 3V, V = 0V, +IN = –IN = V
OCM
= 1.25V,
ENABLE
= 0V, No R
L
unless
otherwise noted.
PARAMETER
Gain
Gain Temperature Drift
Output Swing Low
Output Swing High
Maximum Differential Output Swing
Output Current Drive
Input Offset Voltage
Input Offset Voltage Drift
Input Common Mode Voltage Range, MIN
Input Common Mode Voltage Range, MAX
Input Resistance (+IN, –IN)
Input Capacitance (+IN, –IN)
Output Resistance (+OUT, –OUT)
Filtered Output Resistance (+OUTF –OUTF)
,
Filtered Output Capacitance (+OUTF –OUTF)
,
Common Mode Rejection Ratio
Common Mode Gain
Output Common Mode Range, MIN
Output Common Mode Range, MAX
Common Mode Offset Voltage
Common Mode Offset Voltage Drift
V
OCM
Input Current
ENABLE
Input Low Voltage
ENABLE
Input High Voltage
ENABLE
Input Low Current
ENABLE
Input High Current
Operating Supply Range
Supply Current
Shutdown Supply Current
Power Supply Rejection Ratio
(Differential Outputs)
ENABLE
= 0.8V, Input and Output Floating
ENABLE
= 2.4V, Input and Output Floating
V
+
= 2.85V to 3.5V
ENABLE
= 0.8V
ENABLE
= 2.4V
V
OCM
= 1.1V to 1.5V
Differential
Differential, Includes Parasitic
Differential
Differential
Differential, Includes Parasitic
Input Common Mode Voltage 1.1V~1.7V
V
OCM
= 1V to 1.6V
l
l
l
l
l
l
l
l
l
l
l
l
l
l
l
l
l
SYMBOL
G
DIFF
TC
GAIN
V
SWINGMIN
V
SWINGMAX
V
OUTDIFFMAX
I
OUT
V
OS
TCV
OS
I
VRMIN
I
VRMAX
R
INDIFF
C
INDIFF
R
OUTDIFF
R
OUTFDIFF
C
OUTFDIFF
CMRR
G
CM
V
OCMMIN
V
OCMMAX
V
OSCM
TCV
OSCM
IV
OCM
ENABLE
Pin
V
IL
V
IH
I
IL
I
IH
Power Supply
V
S
I
S
I
SHDN
PSRR
CONDITIONS
V
IN
= ±400mV Differential
V
IN
= ±400mV Differential
Each Output, V
IN
= ±1.6V Differential
Each Output, V
IN
= ±1.6V Differential
1dB Compressed
V
OUT
> 2V
P-P,DIFF
Differential
Differential
l
l
l
l
l
l
l
l
MIN
7.5
TYP
8
–0.13
74
MAX
8.5
170
UNITS
dB
mdB/°C
mV
V
V
P-P
mA
Input/Output Characteristic
2.3
20
–5
2.48
4.8
5
2
1
mV
μV/°C
V
V
Ω
pF
Ω
Ω
pF
dB
V/V
1.8
340
18
85
39
400
1
25
100
2.7
55
1
1
1.1
1.6
1.5
–15
6
4.5
15
0.8
2.4
0.5
1.3
2.85
70
50
3
85
0.9
68
4
3.5
95
3
15
32
115
460
Output Common Mode Voltage Control
V
V
V
V
mV
μV/°C
μA
V
V
μA
μA
V
mA
mA
dB
64008f
3
LTC6400-8
AC ELECTRICAL CHARACTERISTICS
ENABLE
= 0V, No R
L
unless otherwise noted.
SYMBOL
–3dBBW
0.5dBBW
0.1dBBW
1/f
SR
t
S1%
t
OVDR
t
ON
t
OFF
–3dBBW
VOCM
10MHz Input Signal
HD2,10M/HD3,10M Second/Third Order Harmonic Distortion V
OUT
= 2V
P-P
, R
L
= 200Ω
V
OUT
= 2V
P-P
, No R
L
IMD3,10M
OIP3,10M
P1dB,10M
NF10M
e
IN,10M
e
ON,10M
70MHz Input Signal
HD2,70M/HD3,70M Second/Third Order Harmonic Distortion V
OUT
= 2V
P-P
, R
L
= 200Ω
V
OUT
= 2V
P-P
, No R
L
IMD3,70M
OIP3,70M
P1dB,70M
NF70M
e
IN,70M
e
ON,70M
140MHz Input Signal
HD2,140M/
HD3,140M
IMD3,140M
OIP3,140M
Second/Third Order Harmonic Distortion 2V
P-P,OUT
, R
L
= 200Ω
2V
P-P,OUT
, No R
L
Third-Order Intermodulation
(f1 = 139.5MHz f2 = 140.5MHz)
Third-Order Output Intercept Point
(f1 = 139.5MHz f2 = 140.5MHz)
2V
P-P,OUT
Composite, R
L
= 200Ω
2V
P-P,OUT
Composite, No R
L
2V
P-P,OUT
Composite, No R
L
(Notes 7)
–86/–71
–91/–81
–79
–84
45.8
dBc
dBc
dBc
dBc
dBm
Third-Order Intermodulation
(f1 = 69.5MHz f2 = 70.5MHz)
Equivalent Third-Order Output Intercept
Point (f1 = 69.5MHz f2 = 70.5MHz)
1dB Compression Point
Noise Figure
Input Referred Voltage Noise Density
Output Referred Voltage Noise Density
V
OUT
= 2V
P-P
Composite, R
L
= 200Ω
V
OUT
= 2V
P-P
Composite, No R
L
V
OUT
= 2V
P-P
Composite, No R
L
(Note 7)
R
L
= 375Ω (Notes 5, 7)
R
S
= 400Ω, R
L
= 375Ω
Includes Resistors (Short Inputs)
Includes Resistors (Short Inputs)
–97/–85
–100/–98
–90
–99
53.4
19.2
7.6
3.7
9.3
dBc
dBc
dBc
dBc
dBm
dBm
dB
nV/√Hz
nV/√Hz
Third-Order Intermodulation
(f1 = 9.5MHz f2 = 10.5MHz)
Equivalent Third-Order Output Intercept
Point (f1 = 9.5MHz f2 = 10.5MHz)
1dB Compression Point
Noise Figure
Input Referred Voltage Noise Density
Output Referred Voltage Noise Density
V
OUT
= 2V
P-P
Composite, R
L
= 200Ω
V
OUT
= 2V
P-P
Composite, No R
L
V
OUT
= 2V
P-P
Composite, No R
L
(Note 7)
R
L
= 375Ω (Notes 5, 7)
R
S
= 400Ω, R
L
= 375Ω
Includes Resistors (Short Inputs)
Includes Resistors (Short Inputs)
–118/–98
–120/–109
–99
–112
60
18.2
7.6
3.7
9.3
dBc
dBc
dBc
dBc
dBm
dBm
dB
nV/√Hz
nV/√Hz
PARAMETER
–3dB Bandwidth
Bandwidth for 0.5dB Flatness
Bandwidth for 0.1dB Flatness
1/f Noise Corner
Slew Rate
1% Settling Time
Overdrive Recovery Time
Turn-On Time
Turn-Off Time
V
OCM
Pin Small Signal –3dB BW
V
OUT
= 2V Step (Note 6)
V
OUT
= 2V
P-P
(Note 6)
V
OUT
= 1.9V
P-P
(Note 6)
Differential Output Reaches 90% of
Steady State Value
Differential Output Drops to 10% of
Original Value
0.1V
P-P
at V
OCM
, Measured Single-Ended at
Output (Note 6)
Specifications are at T
A
= 25°C. V
+
= 3V, V
–
= 0V, V
OCM
= 1.25V,
MIN
1.2
TYP
2.2
0.43
0.2
16.5
3810
1.8
18
10
12
14
MAX
UNITS
GHz
GHz
GHz
kHz
V/μs
ns
ns
ns
ns
MHz
CONDITIONS
200mV
P-P,OUT
(Note 6)
200mV
P-P,OUT
(Note 6)
200mV
P-P,OUT
(Note 6)
64008f
4
LTC6400-8
AC ELECTRICAL CHARACTERISTICS
ENABLE
= 0V, No R
L
unless otherwise noted.
PARAMETER
1dB Compression Point
Noise Figure
Input Referred Voltage Noise Density
Output Referred Voltage Noise Density
Second-Order Harmonic Distortion
Third-Order Intermodulation
(f1 = 239.5MHz f2 = 240.5MHz)
Third-Order Output Intercept Point
(f1 = 239.5MHz f2 = 240.5MHz)
1dB Compression Point
Noise Figure
Input Referred Voltage Noise Density
Output Referred Voltage Noise Density
Second-Order Harmonic Distortion
Third-Order Intermodulation
(f1 = 299.5MHz f2 = 300.5MHz)
Third-Order Output Intercept Point
(f1 = 299.5MHz f2 = 300.5MHz)
1dB Compression Point
Noise Figure
Input Referred Voltage Noise Density
Output Referred Voltage Noise Density
Third-Order Intermodulation
(f1 = 280MHz f2 = 320MHz) Measured
at 360MHz
SYMBOL
P1dB,140M
NF140M
e
IN,140M
e
ON,140M
240MHz Input Signal
HD2,240M/
HD3,240M
IMD3,240M
OIP3,240M
P1dB,240M
NF240M
e
N, 240M
e
ON,240M
300MHz Input Signal
HD2,300M/
HD3,300M
IMD3,300M
OIP3,300M
P1dB,300M
NF300M
e
N,300M
e
ON,300M
IMD3,280M/320M
2V
P-P,OUT
, R
L
= 200Ω
2V
P-P,OUT
, No R
L
2V
P-P,OUT
Composite, R
L
= 200Ω
2V
P-P,OUT
Composite, No R
L
2V
P-P,OUT
Composite, No R
L
(Note 7)
R
L
= 375Ω (Notes 5, 7)
R
S
= 400Ω, R
L
= 375Ω
Includes Resistors (Short Inputs)
Includes Resistors (Short Inputs)
2V
P-P,OUT
Composite, R
L
= 375Ω
–67/–46
–69/–50
–57
–61
34.8
17.6
8.5
3.8
10
–59
–53
dBc
dBc
dBc
dBc
dBm
dBm
dB
nV/√Hz
nV/√Hz
dBc
2V
P-P,OUT
, R
L
= 200Ω
2V
P-P,OUT
, No R
L
2V
P-P,OUT
Composite, R
L
= 200Ω
2V
P-P,OUT
Composite, No R
L
2V
P-P,OUT
Composite, No R
L
(Note 7)
R
L
= 375Ω (Notes 5, 7)
R
S
= 400Ω, R
L
= 375Ω
Includes Resistors (Short Inputs)
Includes Resistors (Short Inputs)
–71/–53
–73/–59
–64
–68
37.8
18.2
8.1
3.7
9.6
dBc
dBc
dBc
dBc
dBm
dBm
dB
nV/√Hz
nV/√Hz
Specifications are at T
A
= 25°C. V
+
= 3V, V
–
= 0V, V
OCM
= 1.25V,
MIN
TYP
19.2
7.7
3.7
9.3
MAX
UNITS
dBm
dB
nV/√Hz
nV/√Hz
CONDITIONS
R
L
= 375Ω (Notes 5, 7)
R
S
= 400Ω, R
L
= 375Ω
Includes Resistors (Short Inputs)
Includes Resistors (Short Inputs)
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:
Input pins (+IN, –IN) are protected by steering diodes to either
supply. If the inputs go beyond either supply rail, the input current should
be limited to less than 10mA.
Note 3:
The LTC6400C and LTC6400I are guaranteed functional over the
operating temperature range of –40°C to 85°C.
Note 4:
The LTC6400C 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 to 85°C but is not tested or QA sampled at these
temperatures. The LTC6400I is guaranteed to meet specified performance
from –40°C to 85°C.
Note 5:
Input and output baluns used. See Test Circuit A.
Note 6:
Measured using Test Circuit B. R
L
= 87.5Ω per output.
Note 7:
Since the LTC6400-8 is a feedback amplifier with low output
impedance, a resistive load is not required when driving an AD converter.
Therefore, typical output power is very small. In order to compare the
LTC6400-8 with amplifiers that require 50Ω output load, the LTC6400-8
output voltage swing driving a given R
L
is converted to OIP3 and P1dB as
if it were driving a 50Ω load. Using this modified convention, 2V
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