targeted at processing signals from DC to 140MHz. 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 LTC6401-20 is easy to use, with minimal support
circuitry 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 20dB (10V/V).
The LTC6401-20 saves space and power compared to
alternative solutions using IF gain blocks and transform-
ers. The LTC6401-20 is packaged in a compact 16-lead
3mm
×
3mm QFN package and operates over the –40°C
to 85°C temperature range.
, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
■
■
■
1.3GHz –3dB Bandwidth
Fixed Gain of 10V/V (20dB)
–93dBc IMD
3
at 70MHz (Equivalent OIP
3
= 50.5dBm)
–74dBc IMD
3
at 140MHz (Equivalent OIP
3
= 41dBm)
1nV/√
⎯
H
⎯
z Internal Op Amp Noise
2.1nV/√
⎯
H
⎯
z Total Input Noise
6.2dB Noise Figure
Differential Inputs and Outputs
200Ω Input Impedance
2.85V to 3.5V Supply Voltage
50mA Supply Current (150mW)
1V to 1.6V Output Common Mode Voltage,
Adjustable
DC- or AC-Coupled Operation
Max Differential Output Swing 4.4V
P-P
Small 16-Lead 3mm
×
3mm
×
0.75mm QFN Package
APPLICATIONS
■
■
■
■
■
Differential ADC Driver
Differential Driver/Receiver
Single Ended to Differential Conversion
IF Sampling Receivers
SAW Filter Interfacing
TYPICAL APPLICATION
Single-Ended to Differential ADC Driver
3.3V
0.1μF + 1000pF
V
+
0.1μF
INPUT
66.5Ω
0.1μF
+IN
V
OCM
+OUT
+OUTF
LTC6401-20
–OUTF
–OUT
–IN
V–
ENABLE
20dB GAIN
10Ω
AIN
+
V
CM
LTC2208
AIN
–
10Ω
LTC2208 130Msps
16-Bit ADC
640120 TA01a
Equivalent Output IP3 vs Frequency
70
60
3.3V
OUTPUT IP3 (dBm)
50
40
30
20
10
0
0
50
100
150
FREQUENCY (MHz)
200
640120 TA01b
1.25V
0.1μF
(NOTE 7)
V
DD
29Ω
640120f
1
LTC6401-20
ABSOLUTE MAXIMUM RATINGS
(Note 1)
PIN CONFIGURATION
TOP VIEW
–IN
–IN
+IN
7
+OUTF
+IN
12 V–
17
11 ENABLE
10 V
+
9 V–
8
+OUT
16 15 14 13
V
+
V
+
1
UD PACKAGE
16-LEAD (3mm
×
3mm) PLASTIC QFN
T
JMAX
= 150°C,
θ
JA
= 68°C/W,
θ
JC
= 4.2°C/W
EXPOSED PAD (PIN 17) IS V
–
, MUST BE SOLDERED TO PCB
ORDER INFORMATION
LEAD FREE FINISH
LTC6401CUD-20#PBF
LTC6401IUD-20#PBF
TAPE AND REEL
LTC6401CUD-20#TRPBF
LTC6401IUD-20#TRPBF
PART MARKING*
LCDB
LCDB
PACKAGE DESCRIPTION
16-Lead (3mm
×
3mm) Plastic QFN
16-Lead (3mm
×
3mm) Plastic QFN
TEMPERATURE RANGE
0°C to 70°C
–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
LTC6400-20
LTC6401-20
GAIN
(dB)
20
20
GAIN
(V/V)
10
10
Please check each datasheet for complete details.
Z
IN
(DIFFERENTIAL)
(Ω)
200
200
I
CC
(mA)
90
50
In addition to the LTC6401 family of amplifiers, a lower distortion LTC6400 family is available. The LTC6400 is pin compatible to the LTC6401, and has the
same low noise performance. The low distortion of the LTC6400 comes at the expense of higher power consumption. Please refer to the separate LTC6400
data sheets for complete details. Other gain versions from 8dB to 26dB will follow.
–OUTF
–OUT
Supply Voltage (V
+
– V
–
)..........................................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
3
V– 4
5
6
640120f
2
LTC6401-20
DC ELECTRICAL CHARACTERISTICS
+
The
●
–
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,
⎯
E
⎯
N
⎯
A
⎯
B
⎯
L
⎯
E = 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
Input Capacitance
Output Resistance
Filtered Output Resistance
Filtered Output Capacitance
Common Mode Rejection Ratio
Common Mode Gain
Output Common Mode Range, MIN
●
SYMBOL
G
DIFF
G
TEMP
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
⎯
E
⎯
N
⎯
A
⎯
B
⎯
L
⎯
E Pin
V
IL
V
IH
I
IL
I
IH
Power Supply
V
S
I
S
I
SHDN
PSRR
CONDITIONS
V
IN
= ±100mV Differential
V
IN
= ±100mV Differential
Each Output, V
IN
= ±400mV Differential
Each Output, V
IN
= ±400mV Differential
1dB Compressed
Single-Ended
Differential
Differential
●
●
●
●
●
●
●
MIN
19.4
TYP
20
1
90
MAX
20.6
170
UNITS
dB
mdB/°C
mV
V
V
P-P
mA
Input/Output Characteristic
2.3
10
–2
2.44
4.4
2
1.4
1
mV
μV/°C
V
V
Ω
pF
Ω
Ω
pF
dB
V/V
1.6
Differential
Differential, Includes Parasitic
Differential
Differential
Differential, Includes Parasitic
Input Common Mode Voltage 1.1V to 1.4V
V
OCM
= 1V to 1.6V
●
●
●
●
170
18
85
45
200
1
25
100
2.7
66
1
230
32
115
Output Common Mode Voltage Control
1
1.1
1.6
1.5
–15
6
5
15
0.8
2.4
±0.5
1.2
2.85
38
55
3
50
1
84
3
3.5
62
3
15
V
V
V
V
mV
μV/°C
μA
V
V
μA
μA
V
mA
mA
dB
Output Common Mode Range, MAX
●
Common Mode Offset Voltage
Common Mode Offset Voltage Drift
V
OCM
Input Current
⎯
E
⎯
N
⎯
A
⎯
B
⎯
L
⎯
E Input Low Voltage
⎯
E
⎯
N
⎯
A
⎯
B
⎯
L
⎯
E Input High Voltage
⎯
E
⎯
N
⎯
A
⎯
B
⎯
L
⎯
E Input Low Current
⎯
E
⎯
N
⎯
A
⎯
B
⎯
L
⎯
E Input High Current
Operating Supply Range
Supply Current
Shutdown Supply Current
Power Supply Rejection Ratio
(Differential Outputs)
V
OCM
= 1.1V to 1.5V
●
●
●
●
●
⎯
EN
⎯
A
⎯
B
⎯
L
⎯
E = 0.8V
⎯
⎯
EN
⎯
A
⎯
B
⎯
L
⎯
E = 2.4V
⎯
●
●
●
⎯
E
⎯
N
⎯
A
⎯
B
⎯
L
⎯
E = 0.8V
⎯
EN
⎯
A
⎯
B
⎯
L
⎯
E = 2.4V
⎯
2.85V to 3.5V
●
●
●
640120f
3
LTC6401-20
AC ELECTRICAL CHARACTERISTICS
SYMBOL
–3dBBW
0.1dBBW
0.5dBBW
1/f
SR
t
S1%
t
OVDR
t
ON
t
OFF
–3dBBW
CM
10MHz Input Signal
HD
2,10M
/HD
3,10M
Second/Third Order Harmonic
Distortion
2V
P-P,OUT
, R
L
= 400Ω
2V
P-P,OUT
, No R
L
2V
P-P,OUTFILT
, No R
L
IMD
3,10M
Third-Order Intermodulation
(f1 = 9.5MHz f2 = 10.5MHz)
2V
P-P,OUT
Composite, R
L
= 400Ω
2V
P-P,OUT
Composite, No R
L
2V
P-P,OUTFILT
Composite, No R
L
OIP
3,10M
P
1dB,10M
NF
10M
e
IN,10M
e
ON,10M
70MHz Input Signal
HD
2,70M
/HD
3,70M
Second/Third Order Harmonic
Distortion
2V
P-P,OUT
, R
L
= 400Ω
2V
P-P,OUT
, No R
L
2V
P-P,OUTFILT
, No R
L
IMD
3,70M
Third-Order Intermodulation
(f1 = 69.5MHz f2 = 70.5MHz)
2V
P-P,OUT
Composite, R
L
= 400Ω
2V
P-P,OUT
Composite, No R
L
2V
P-P,OUTFILT
Composite, No R
L
OIP
3,70M
P
1dB,70M
NF
70M
e
IN,70M
e
ON,70M
140MHz Input Signal
HD
2,140M
/HD
3,140M
Second/Third Order Harmonic
Distortion
2V
P-P,OUT
, R
L
= 400Ω
2V
P-P,OUT
, No R
L
2V
P-P,OUTFILT
, No R
L
–80/–57
–81/–60
–80/–65
dBc
dBc
dBc
Third-Order Output Intercept Point
(f1 = 69.5MHz f2 = 70.5MHz)
1dB Compression Point
Noise Figure
Input Referred Voltage Noise Density
2V
P-P,OUT
Composite, No R
L
(Note 7)
R
L
= 375Ω (Notes 5, 7)
R
L
= 375Ω (Note 5)
Includes Resistors (Short Inputs)
–91/–80
–95/–88
–95/–88
–88
–93
–92
50.5
17.3
6.1
2.1
21
dBc
dBc
dBc
dBc
dBc
dBc
dBm
dBm
dB
nV/√
⎯
H
⎯
z
⎯
nV/√H
⎯
z
Third-Order Output Intercept Point
(f1 = 9.5MHz f2 = 10.5MHz)
1dB Compression Point
Noise Figure
Input Referred Voltage Noise Density
2V
P-P,OUT
Composite, No R
L
(Note 7)
R
L
= 375Ω (Notes 5, 7)
R
L
= 375Ω (Note 5)
Includes Resistors (Short Inputs)
–122/–92
–110/–103
–113/–102
–96
–108
–105
58
17.3
6.2
2.1
21
dBc
dBc
dBc
dBc
dBc
dBc
dBm
dBm
dB
⎯
nV/√H
⎯
z
⎯
nV/√H
⎯
z
PARAMETER
–3dB Bandwidth
Bandwidth for 0.1dB Flatness
Bandwidth for 0.5dB Flatness
1/f Noise Corner
Slew Rate
1% Settling Time
Output Overdrive Recovery Time
Turn-On Time
Turn-Off Time
Common Mode Small Signal –3dB
BW
Differential (Note 6)
2V
P-P,OUT
(Note 6)
1.9V
P-P,OUT
(Note 6)
+OUT, –OUT Within 10% of Final Values
I
CC
Falls to 10% of Nominal
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, +IN and –IN
floating, V
OCM
= 1.25V,
⎯
E
⎯
N
⎯
A
⎯
B
⎯
L
⎯
E = 0V, No R
L
unless otherwise noted.
CONDITIONS
200mV
P-P,OUT
(Note 6)
200mV
P-P,OUT
(Note 6)
200mV
P-P,OUT
(Note 6)
MIN
TYP
1.25
130
250
12.5
4500
2
7
78
146
15
MAX
UNITS
GHz
MHz
MHz
kHz
V/μs
ns
ns
ns
ns
MHz
Output Referred Voltage Noise Density Includes Resistors (Short Inputs)
Output Referred Voltage Noise Density Includes Resistors (Short Inputs)
640120f
4
LTC6401-20
AC ELECTRICAL CHARACTERISTICS
SYMBOL
IMD
3,140M
PARAMETER
Third-Order Intermodulation
(f1 = 139.5MHz f2 = 140.5MHz)
Specifications are at T
A
= 25°C. V
+
= 3V, V
–
= 0V, +IN and –IN
floating, V
OCM
= 1.25V,
⎯
E
⎯
N
⎯
A
⎯
B
⎯
L
⎯
E = 0V, No R
L
unless otherwise noted.
CONDITIONS
2V
P-P,OUT
Composite, R
L
= 400Ω
2V
P-P,OUT
Composite, No R
L
2V
P-P,OUTFILT
Composite, No R
L
2V
P-P,OUT
Composite, No R
L
(Note 7)
R
L
= 375Ω (Notes 5, 7)
R
L
= 375Ω (Note 5)
Includes Resistors (Short Inputs)
2V
P-P,OUT
Composite, R
L
= 375Ω (Note 5)
–61
MIN
TYP
–71
–74
–72
41
18
6.4
2.1
22
–69
MAX
UNITS
dBc
dBc
dBc
dBm
dBm
dB
⎯
nV/√H
⎯
z
⎯
nV/√H
⎯
z
dBc
OIP
3,140M
P
1dB,140M
NF
140M
e
IN,140M
e
ON,140M
IMD
3,130M/150M
Third-Order Output Intercept Point
(f1 = 139.5MHz f2 = 140.5MHz)
1dB Compression Point
Noise Figure
Input Referred Voltage Noise Density
Third-Order Intermodulation
(f1 = 130MHz f2 = 150MHz) Measure
at 170MHz
Output Referred Voltage Noise Density 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 LTC6401C and LTC6401I are guaranteed functional over the
operating temperature range of –40°C to 85°C.
Note 4:
The LTC6401C 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 LTC6401I 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.
Note 7:
Since the LTC6401-20 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
LTC6401-20 with amplifiers that require 50Ω output load, the LTC6401-20
output voltage swing driving a given R
L
is converted to OIP
3
and P
1dB
as
if it were driving a 50Ω load. Using this modified convention, 2V
P-P
is by
definition equal to 10dBm, regardless of the actual R
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