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 LTC6401-14 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 14dB (5V/V).
The LTC6401-14 saves space and power compared to
alternative solutions using IF gain blocks and transform-
ers. The LTC6401-14 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.
2GHz –3dB Bandwidth
Fixed Gain of 5V/V (14dB)
–91dBc IMD3 at 70MHz (Equivalent OIP3 = 49.3dBm)
–81dBc IMD3 at 140MHz (Equivalent OIP3 = 44.5dBm)
1.1nV/√
⎯
H
⎯
z Internal Op Amp Noise
7.3dB Noise Figure
Differential Inputs and Outputs
200Ω Input Impedance
2.85V to 3.5V Supply Voltage
45mA Supply Current (135mW)
1V to 1.6V Output Common Mode, Adjustable
DC- or AC-Coupled Operation
Max Differential Output Swing 4.6V
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
3.3V
3.3V
60
C2
0.1μF
C1
1000pF
C3
0.1μF
V
IN
R1
68.5Ω
C4
0.1μF
–IN
R2
29Ω
V–
1.25V
C5
0.1μF
R3
100Ω
V
+
+IN
+OUT
LTC6401-14
–OUT
V
OCM
COILCRAFT
0603CS
L1
R
S2
24nH
15Ω
C
F1
33pF R
S4
10Ω
C
F3
33pF
R
S1
15Ω
C
F2
33pF
OUTPUT IP3 (dBm)
R
S3
10Ω
50
40
30
20
10
640114 TA01a
Equivalent Output IP3 vs Frequency
(NOTE 7)
AIN
+
V
DD
LTC2208
AIN
–
V
CM
LTC2208
130Msps
16-Bit ADC
0
0
20 40 60 80 100 120 140 160 180 200
FREQUENCY (MHz)
640114 TA01b
640114f
1
LTC6401-14
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
+
+
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
1
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
= 4.2°C/W
EXPOSED PAD (PIN 17) IS V
–
, MUST BE SOLDERED TO PCB
ORDER INFORMATION
LEAD FREE FINISH
LTC6401CUD-14#PBF
LTC6401IUD-14#PBF
TAPE AND REEL
LTC6401CUD-14#TRPBF
LTC6401IUD-14#TRPBF
PART MARKING*
LCCZ
LCCZ
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 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 LTC6400 shows higher linearity especially at input frequencies above 140MHz at the expense of higher supply current.
Please refer to the separate LTC6400 data sheets for complete details.
640114f
2
LTC6401-14
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 (+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
●
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
⎯
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
= ±200mV Differential
V
IN
= ±200mV Differential
Each Output, V
IN
= ±800mV Differential
Each Output, V
IN
= ±800mV Differential
1dB Compressed
V
OUT
> 2V
P-P,DIFF
Differential
Differential
●
●
●
●
●
●
●
●
MIN
13.5
TYP
14
–0.3
93
MAX
14.5
170
UNITS
dB
mdB/°C
mV
V
V
P-P
mA
Input/Output Characteristic
2.3
10
–3
2.42
4.6
3
1.2
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~1.4V
V
OCM
= 1V to 1.6V
●
●
●
●
170
18
85
40
200
1
25
100
2.7
62
1
230
32
115
Output Common Mode Voltage Control
1
1.1
1.6
1.5
–15
–6
3.7
15
0.8
2.4
0.5
1.4
2.85
36
55
3
45
0.8
80
4
3.5
60
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
⎯
⎯
E
⎯
N
⎯
A
⎯
B
⎯
L
⎯
E = 2.4V
●
●
●
⎯
EN
⎯
A
⎯
B
⎯
L
⎯
E = 0.8V, Input and Output Floating
⎯
⎯
EN
⎯
A
⎯
B
⎯
L
⎯
E = 2.4V, Input and Output Floating
⎯
V
+
= 2.85V to 3.5V
●
●
●
640114f
3
LTC6401-14
AC ELECTRICAL CHARACTERISTICS
⎯
E
⎯
N
⎯
A
⎯
B
⎯
L
⎯
E = 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
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
L
= 375Ω (Note 5)
Includes Resistors (Short Inputs)
Includes Resistors (Short Inputs)
–95/–69
–101/–89
–80
–91
49.3
17.7
7.3
2.5
12.5
dBc
dBc
dBc
dBc
dBm
dBm
dB
⎯
nV/√H
⎯
z
⎯
nV/√H
⎯
z
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
L
= 375Ω (Note 5)
Includes Resistors (Short Inputs)
Includes Resistors (Short Inputs)
–106/–83
–118/–102
–88
–95
51.5
17.4
7.3
2.5
12.5
dBc
dBc
dBc
dBc
dBm
dBm
dB
⎯
nV/√H
⎯
z
⎯
nV/√H
⎯
z
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)
V
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, V
OCM
= 1.25V,
MIN
1
TYP
1.95
0.47
0.23
15
3600
1.8
18
87
150
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)
640114f
4
LTC6401-14
AC ELECTRICAL CHARACTERISTICS
⎯
EN
⎯
A
⎯
B
⎯
L
⎯
E = 0V, No R
L
unless otherwise noted.
⎯
PARAMETER
SYMBOL
140MHz Input Signal
HD2,140M/
HD3,140M
IMD3,140M
OIP3,140M
P1dB,140M
NF140M
e
IN,140M
e
ON,140M
IMD3,130M/150M
Second/Third Order Harmonic Distortion V
OUT
= 2V
P-P
, R
L
= 200Ω
V
OUT
= 2V
P-P
, No R
L
Third-Order Intermodulation
(f1 = 139.5MHz f2 = 140.5MHz)
Equivalent Third-Order Output Intercept
Point (f1 = 139.5MHz f2 = 140.5MHz)
1dB Compression Point
Noise Figure
Input Referred Voltage Noise Density
Output Referred Voltage Noise Density
Third-Order Intermodulation
(f1 = 130MHz f2 = 150MHz) Measure at
170MHz
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
L
= 375Ω (Note 5)
Includes Resistors (Short Inputs)
Includes Resistors (Short Inputs)
V
OUT
= 2V
P-P
Composite, R
L
= 375Ω
–79/–57
–87/–69
–70
–81
44.5
17.7
7.4
2.5
12.5
–70
–61
dBc
dBc
dBc
dBc
dBm
dBm
dB
⎯
nV/√H
⎯
z
nV/√
⎯
H
⎯
z
dBc
Specifications are at T
A
= 25°C. V
+
= 3V, V
–
= 0V, V
OCM
= 1.25V,
MIN
TYP
MAX
UNITS
CONDITIONS
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. R
L
= 87.5Ω per output.
Note 7:
Since the LTC6401-14 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
LTC6401-14 with amplifiers that require 50Ω output load, the LTC6401-14
output voltage swing driving a given R
L
is converted to OIP3 and P
1dB
as
if it were driving a 50Ω load. Using this modified convention, 2V
http://www.21ic.com/news/upload/2005_12/05120611543180.gif
This circuit was submitted by Graham Maynard from Newtownabbey, Northern Ireland. It has an exceptionally fast high freq ......
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