FeaTures
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LTC6409
10GHz GBW, 1.1nV/√Hz
Differential Amplifier/ADC
Driver
DescripTion
The LTC
®
6409 is a very high speed, low distortion, dif-
ferential amplifier. Its input common mode range includes
ground, so that a ground-referenced input signal can be
DC-coupled, level-shifted, and converted to drive an ADC
differentially.
The gain and feedback resistors are external, so that the
exact gain and frequency response can be tailored to each
application. For example, the amplifier could be externally
compensated in a no-overshoot configuration, which is
desired in certain time-domain applications.
The LTC6409 is stable in a differential gain of 1. This al-
lows for a low output noise in applications where gain is
not desired. It draws 52mA of supply current and has a
hardware shutdown feature which reduces current con-
sumption to 100µA.
The LTC6409 is available in a compact 3mm
×
2mm 10-pin
leadless QFN package and operates over a –40°C to 125°C
temperature range.
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.
10GHz Gain-Bandwidth Product
88dB SFDR at 100MHz, 2V
P-P
1.1nV/√Hz Input Noise Density
Input Range Includes Ground
External Resistors Set Gain (Min 1V/V)
3300V/µs Differential Slew Rate
52mA Supply Current
2.7V to 5.25V Supply Voltage Range
Fully Differential Input and Output
Adjustable Output Common Mode Voltage
Low Power Shutdown
Small 10-Lead 3mm
×
2mm
×
0.75mm QFN Package
applicaTions
n
n
n
n
n
Differential Pipeline ADC Driver
High-Speed Data-Acquisition Cards
Automated Test Equipment
Time Domain Reflexometry
Communications Receivers
Typical applicaTion
DC-Coupled Interface from a Ground-Referenced Single-Ended
Input to an LTC2262-14 ADC
1.3pF
0
V
IN
LTC6409 Driving LTC2262-14 ADC,
f
IN
= 70MHz, –1dBFS,
f
S
= 150MHz, 4096-Point FFT
V
S
= 3.3V
–10 V
OUTDIFF
= 1.8V
P-P
–20 HD2 = –86.5dBc
HD3 = –89.4dBc
–30
SFDR = 81.6dB
–40 SNR = 71.1dB
–50
–60
–70
–80
–90
–100
–110
–120
0
10
20
30
40
50
FREQUENCY (MHz)
60
70
6409 TA01b
150
150
1.8V
3.3V
39pF
33.2
10
A
IN+
A
IN–
V
DD
AMPLITUDE (dBFS)
– +
V
OCM
= 0.9V
LTC6409
+ –
150
150
33.2
10
39pF
LTC2262-14 ADC
GND
6409 TA01
1.3pF
6409fa
1
LTC6409
absoluTe MaxiMuM raTings
(Note 1)
pin conFiguraTion
TOP VIEW
V
–
10
–OUT
+IN
1
2
3
SHDN
4
V
+
5
V
OCM
V
+
9
11,V
–
V
–
8
7
6
+OUT
–IN
Total Supply Voltage (V
+
– V
–
) .................................5.5V
Input Current (+IN, –IN, V
OCM
,
SHDN)
(Note 2) ................................................................ ±10mA
Output Short-Circuit Duration (Note 3) ............ Indefinite
Operating Temperature Range
(Note 4).................................................. –40°C to 125°C
Specified Temperature Range
(Note 5).................................................. –40°C to 125°C
Maximum Junction Temperature .......................... 150°C
Storage Temperature Range .................. –65°C to 150°C
UDB PACKAGE
10-LEAD (3mm
×
2mm) PLASTIC QFN
T
JMAX
= 150°C,
θ
JA
= 138°C/W,
θ
JC
= 5.2°C/W
EXPOSED PAD (PIN 11) CONNECTED TO V
–
orDer inForMaTion
Lead Free Finish
TAPE AND REEL (MINI)
LTC6409CUDB#TRMPBF
LTC6409IUDB#TRMPBF
LTC6409HUDB#TRMPBF
TAPE AND REEL
LTC6409CUDB#TRPBF
LTC6409IUDB#TRPBF
LTC6409HUDB#TRPBF
PART MARKING*
LFPF
LFPF
LFPF
PACKAGE DESCRIPTION
10-Lead (3mm
×
2mm) Plastic QFN
10-Lead (3mm
×
2mm) Plastic QFN
SPECIFIED TEMPERATURE RANGE
0°C to 70°C
–40°C to 85°C
–40°C to 125°C
10-Lead (3mm
×
2mm) Plastic QFN
TRM = 500 pieces. *Temperature grades are identified by a label on the shipping container.
Consult LTC Marketing for parts specified with wider operating temperature ranges.
Consult LTC Marketing for information on 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/
The
l
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
+
= 5V, V
–
= 0V, V
CM
= V
OCM
= V
ICM
= 1.25V, V
SHDN
= open. V
S
is
defined as (V
+
– V
–
). V
OUTCM
is defined as (V
+OUT
+ V
–OUT
)/2. V
ICM
is defined as (V
+IN
+ V
–IN
)/2. V
OUTDIFF
is defined as (V
+OUT
– V
–OUT
).
SYMBOL PARAMETER
V
OSDIFF
Differential Offset Voltage (Input Referred)
CONDITIONS
V
S
= 3V
V
S
= 3V
V
S
= 5V
V
S
= 5V
V
S
= 3V
V
S
= 5V
V
S
= 3V
V
S
= 5V
V
S
= 3V
V
S
= 5V
Common Mode
Differential Mode
Differential Mode
f = 1MHz, Not Including R
I
/R
F
Noise
f = 1MHz, Not Including R
I
/R
F
Noise
Shunt-Terminated to 50Ω, R
S
= 50Ω, R
I
= 25Ω,
R
F
= 10kΩ
l
elecTrical characTerisTics
MIN
TYP
±300
±300
MAX
±1000
±1200
±1100
±1400
UNITS
µV
µV
µV
µV
µV/°C
µV/°C
l
l
l
l
l
l
l
ΔV
OSDIFF
Differential Offset Voltage Drift (Input Referred)
ΔT
I
B
I
OS
R
IN
C
IN
e
n
i
n
NF
Input Bias Current (Note 6)
Input Offset Current (Note 6)
Input Resistance
Input Capacitance
Differential Input Noise Voltage Density
Input Noise Current Density
Noise Figure at 100MHz
2
2
–140
–160
–62
–70
±2
±2
165
860
0.5
1.1
8.8
6.9
0
0
±10
±10
µA
µA
µA
µA
kΩ
Ω
pF
nV/√Hz
pA/√Hz
dB
6409fa
2
LTC6409
elecTrical characTerisTics
SYMBOL PARAMETER
e
nVOCM
V
ICMR
(Note 7)
CMRRI
(Note 8)
Common Mode Noise Voltage Density
Input Signal Common Mode Range
Input Common Mode Rejection Ratio
(Input Referred) ΔV
ICM
/ΔV
OSDIFF
The
l
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
+
= 5V, V
–
= 0V, V
CM
= V
OCM
= V
ICM
= 1.25V, V
SHDN
= open. V
S
is
defined as (V
+
– V
–
). V
OUTCM
is defined as (V
+OUT
+ V
–OUT
)/2. V
ICM
is defined as (V
+IN
+ V
–IN
)/2. V
OUTDIFF
is defined as (V
+OUT
– V
–OUT
).
CONDITIONS
f = 10MHz
V
S
= 3V
V
S
= 5V
V
S
= 3V, V
ICM
from 0V to 1.5V
V
S
= 5V, V
ICM
from 0V to 3.5V
V
S
= 3V, V
OCM
from 0.5V to 1.5V
V
S
= 5V, V
OCM
from 0.5V to 3.5V
V
S
= 2.7V to 5.25V
V
S
= 2.7V to 5.25V
l
l
l
l
l
l
l
l
l
MIN
0
0
75
75
55
60
60
55
2.7
TYP
12
MAX
1.5
3.5
UNITS
nV/√Hz
V
V
dB
dB
dB
dB
dB
dB
90
90
80
85
85
70
5.25
1
1
±0.1
±0.1
–65
–70
±1
±1
4
±0.3
±0.3
–50
–50
±5
±6
CMRRIO Output Common Mode Rejection Ratio (Input
(Note 8) Referred) ΔV
OCM
/ΔV
OSDIFF
PSRR
(Note 9)
Differential Power Supply Rejection (ΔV
S
/ΔV
OSDIFF
)
PSRRCM Output Common Mode Power Supply Rejection
(Note 9) (ΔV
S
/ΔV
OSCM
)
Supply Voltage Range (Note 10)
V
S
G
CM
ΔG
CM
BAL
Common Mode Gain (ΔV
OUTCM
/ΔV
OCM
)
Common Mode Gain Error, 100
×
(G
CM
– 1)
Output Balance
(ΔV
OUTCM
/ ΔV
OUTDIFF
)
Common Mode Offset Voltage (V
OUTCM
– V
OCM
)
Common Mode Offset Voltage Drift
V
V/V
V/V
%
%
dB
dB
mV
mV
µV/°C
V
S
= 3V, V
OCM
from 0.5V to 1.5V
V
S
= 5V, V
OCM
from 0.5V to 3.5V
V
S
= 3V, V
OCM
from 0.5V to 1.5V
V
S
= 5V, V
OCM
from 0.5V to 3.5V
ΔV
OUTDIFF
= 2V
Single-Ended Input
Differential Input
V
S
= 3V
V
S
= 5V
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l
l
l
l
l
l
l
l
V
OSCM
ΔV
OSCM
ΔT
V
OUTCMR
Output Signal Common Mode Range
(Note 7) (Voltage Range for the V
OCM
Pin)
R
INVOCM
Input Resistance, V
OCM
Pin
V
OCM
V
OUT
Self-Biased Voltage at the V
OCM
Pin
Output Voltage, High, Either Output Pin
V
S
= 3V
V
S
= 5V
V
S
= 3V, V
OCM
= Open
V
S
= 5V, V
OCM
= Open
V
S
= 3V, I
L
= 0
V
S
= 3V, I
L
= –20mA
V
S
= 5V, I
L
= 0
V
S
= 5V, I
L
= –20mA
V
S
= 3V, 5V; I
L
= 0
V
S
= 3V, 5V; I
L
= 20mA
V
S
= 3V
V
S
= 5V
l
l
l
l
l
l
l
l
l
l
l
l
0.5
0.5
30
0.9
1.85
1.8
3.85
3.8
40
0.85
1.25
2
1.95
4
3.95
0.06
0.2
±50
±70
±70
±95
65
52
1.5
3.5
50
1.6
V
V
KΩ
V
V
V
V
V
V
Output Voltage, Low, Either Output Pin
I
SC
A
VOL
I
S
I
SHDN
R
SHDN
V
IL
V
IH
t
ON
t
OFF
Output Short-Circuit Current, Either Output Pin
(Note 11)
Large-Signal Open Loop Voltage Gain
Supply Current
0.15
0.4
V
V
mA
mA
dB
l
56
58
500
185
0.6
mA
mA
µA
KΩ
V
V
ns
ns
Supply Current in Shutdown
SHDN
Pull-Up Resistor
SHDN
Input Logic Low
SHDN
Input Logic High
Turn-On Time
Turn-Off Time
V
SHDN
≤ 0.6V
V
SHDN
= 0V to 0.5V
l
l
l
l
100
115
1.4
160
80
150
6409fa
3
LTC6409
elecTrical characTerisTics
SYMBOL PARAMETER
SR
Slew Rate
The
l
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
+
= 5V, V
–
= 0V, V
CM
= V
OCM
= V
ICM
= 1.25V, V
SHDN
= open. V
S
is
defined as (V
+
– V
–
). V
OUTCM
is defined as (V
+OUT
+ V
–OUT
)/2. V
ICM
is defined as (V
+IN
+ V
–IN
)/2. V
OUTDIFF
is defined as (V
+OUT
– V
–OUT
).
CONDITIONS
Differential Output, V
OUTDIFF
= 4V
P-P
+OUT Rising (–OUT Falling)
+OUT Falling (–OUT Rising)
R
I
= 25Ω, R
F
= 10kΩ, f
TEST
= 100MHz
l
MIN
TYP
3300
1720
1580
MAX
UNITS
V/µs
V/µs
V/µs
GHz
GHz
GHz
MHz
MHz
GBW
f
–3dB
f
0.1dB
FPBW
HD2
HD3
Gain-Bandwidth Product
–3dB Frequency
Frequency for 0.1dB Flatness
Full Power Bandwidth
25MHz Distortion
9.5
8
10
2
600
550
R
I
= R
F
= 150Ω, R
LOAD
= 400Ω, C
F
= 1.3pF
R
I
= R
F
= 150Ω, R
LOAD
= 400Ω , C
F
= 1.3pF
V
OUTDIFF
= 2V
P-P
Differential Input, V
OUTDIFF
= 2V
P-P
,
R
I
= R
F
= 150Ω, R
LOAD
= 400Ω
2nd Harmonic
3rd Harmonic
Differential Input, V
OUTDIFF
= 2V
P-P
,
R
I
= R
F
= 150Ω, R
LOAD
= 400Ω
2nd Harmonic
3rd Harmonic
Single-Ended Input, V
OUTDIFF
= 2V
P-P
,
R
I
= R
F
= 150Ω, R
LOAD
= 400Ω
2nd Harmonic
3rd Harmonic
Single-Ended Input, V
OUTDIFF
= 2V
P-P
,
R
I
= R
F
= 150Ω, R
LOAD
= 400Ω
2nd Harmonic
3rd Harmonic
V
OUTDIFF
= 2V
P-P
Envelope, R
I
= R
F
= 150Ω,
R
LOAD
= 400Ω
V
OUTDIFF
= 2V
P-P
Envelope, R
I
= R
F
= 150Ω,
R
LOAD
= 400Ω
V
OUTDIFF
= 2V
P-P
Envelope, R
I
= R
F
= 150Ω,
R
LOAD
= 400Ω
–104
–106
dBc
dBc
100MHz Distortion
–93
–88
dBc
dBc
HD2
HD3
25MHz Distortion
–101
–103
dBc
dBc
100MHz Distortion
–88
–93
–110
–98
–88
59
53
48
dBc
dBc
dBc
dBc
dBc
dBm
dBm
dBm
IMD3
3rd Order IMD at 25MHz
f1 = 24.9MHz, f2 = 25.1MHz
3rd Order IMD at 100MHz
f1 = 99.9MHz, f2 = 100.1MHz
3rd Order IMD at 140MHz
f1 = 139.9MHz, f2 = 140.1MHz
OIP3
Equivalent OIP3 at 25MHz (Note 12)
Equivalent OIP3 at 100MHz (Note 12)
Equivalent OIP3 at 140MHz (Note 12)
Settling Time
V
OUTDIFF
= 2V
P-P
Step, R
I
= R
F
= 150Ω,
R
LOAD
= 400Ω
1% Settling
t
S
1.9
ns
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, V
OCM
, and
SHDN)
are protected by steering
diodes to either supply. If the inputs should exceed either supply voltage,
the input current should be limited to less than 10mA. In addition, the
inputs +IN, –IN are protected by a pair of back-to-back diodes. If the
differential input voltage exceeds 1.4V, the input current should be limited
to less than 10mA.
Note 3:
A heat sink may be required to keep the junction temperature
below the absolute maximum rating when the output is shorted
indefinitely.
Note 4:
The LTC6409C/LTC6409I are guaranteed functional over the
temperature range of –40°C to 85°C. The LTC6409H is guaranteed
functional over the temperature range of –40°C to 125°C.
Note 5:
The LTC6409C is guaranteed to meet specified performance from
0°C to 70°C. The LTC6409C 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 LTC6409I is guaranteed to meet
specified performance from –40°C to 85°C. The LTC6409H is guaranteed
to meet specified performance from –40°C to 125°C.
Note 6:
Input bias current is defined as the average of the input currents
flowing into the inputs (–IN and +IN). Input offset current is defined as the
difference between the input currents (I
OS
= I
B+
– I
B–
).
6409fa
4
LTC6409
elecTrical characTerisTics
Note 7:
Input common mode range is tested by testing at both V
ICM
= 1.25V
and at the Electrical Characteristics table limits to verify that the differential
offset (V
OSDIFF
) and the common mode offset (V
OSCM
) have not deviated by
more than ±1mV and ±2mV respectively from the V
ICM
= 1.25V case.
The voltage range for the output common mode range is tested by
applying a voltage on the V
OCM
pin and testing at both V
OCM
= 1.25V and
at the Electrical Characteristics table limits to verify that the common
mode offset (V
OSCM
) has not deviated by more than ±6mV from the
V
OCM
= 1.25V case.
Note 8:
Input CMRR is defined as the ratio of the change in the input
common mode voltage at the pins +IN or –IN to the change in differential
input referred offset voltage. Output CMRR is defined as the ratio of
the change in the voltage at the V
OCM
pin to the change in differential
input referred offset voltage. This specification is strongly dependent on
feedback ratio matching between the two outputs and their respective
inputs and it is difficult to measure actual amplifier performance (See
Effects of Resistor Pair Mismatch in the Applications Information section
of this data sheet). For a better indicator of actual amplifier performance
independent of feedback component matching, refer to the PSRR
specification.
Note 9:
Differential power supply rejection (PSRR) is defined as the ratio
of the change in supply voltage to the change in differential input referred
offset voltage. Common mode power supply rejection (PSRRCM) is
defined as the ratio of the change in supply voltage to the change in the
output common mode offset voltage.
Note 10:
Supply voltage range is guaranteed by power supply rejection
ratio test.
Note 11:
Extended operation with the output shorted may cause the
junction temperature to exceed the 150°C limit.
Note 12:
Refer to Relationship Between Different Linearity Metrics in the
Applications Information section of this data sheet for information on how
to calculate an equivalent OIP3 from IMD3 measurements.
Typical perForMance characTerisTics
Differential Input Offset Voltage
vs Temperature
1.5
2.0
Differential Input Offset Voltage
vs Input Common Mode Voltage
COMMON MODE OFFSET VOLTAGE (mV)
V
S
= 5V
V
OCM
= 1.25V
1.5 R
I
= R
F
= 150
0.1% FEEDBACK NETWORK RESISTORS
REPRESENTATIVE UNIT
1.0
0.5
0
–0.5
2.5
2.0
1.5
1.0
0.5
0
Common Mode Offset Voltage
vs Temperature
DIFFERENTIAL V
OS
(mV)
DIFFERENTIAL V
OS
(mV)
1.0
0.5 V
S
= 5V
V
OCM
= V
ICM
= 1.25V
R
I
= R
F
= 150
FIVE REPRESENTATIVE UNITS
0
V
S
= 5V
V
OCM
= V
ICM
= 1.25V
R
I
= R
F
= 150
FIVE REPRESENTATIVE UNITS
–0.5
–50
–25
0
25
50
75
TEMPERATURE (°C)
100
125
–1.0
T
A
= 85°C
T
A
= 70°C
T
A
= 25°C
T
A
= 0°C
T
A
= –40°C
0
0.5 1 1.5 2 2.5 3 3.5
INPUT COMMON MODE VOLTAGE (V)
4
–0.5
–50
–25
6409 G01
6409 G02
0
25
50
75
TEMPERATURE (°C)
100
125
6409 G03
Supply Current vs Supply Voltage
60
55
TOTAL SUPPLY CURRENT (mA)
50
45
40
35
30
25
20
15
10
5
0
T
A
= 125°C
T
A
= 85°C
T
A
= 70°C
T
A
= 25°C
T
A
= 0°C
T
A
= –40°C
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5
SUPPLY VOLTAGE (V)
6409 G04
Supply Current vs
SHDN
Voltage
60
55
TOTAL SUPPLY CURRENT (mA)
50
45
40
35
30
25
20
15
10
5
0
0
0.5
1
1.5 2 2.5 3 3.5
SHDN
VOLTAGE (V)
T
A
= 125°C
T
A
= 85°C
T
A
= 70°C
T
A
= 25°C
T
A
= 0°C
T
A
= –40°C
4
4.5
5
V
S
= 5V
SHUTDOWN SUPPLY CURRENT (µA)
140
120
100
80
60
40
20
0
Shutdown Supply Current vs
Supply Voltage
T
A
= 125°C
T
A
= 85°C
T
A
= 70°C
T
A
= 25°C
T
A
= 0°C
T
A
= –40°C
V
SHDN
= OPEN
V
SHDN
= V
–
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5
SUPPLY VOLTAGE (V)
6409 G06
6409 G05
6409fa
5
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