LTC6419
Dual 10GHz GBW,
1.1nV/√Hz Differential
Amplifier/ADC Driver
FEATURES
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DESCRIPTION
The
LTC
®
6419
is a dual very high speed, low distortion,
differential amplifier. Its input common mode range in-
cludes ground, so that a ground-referenced single-ended
or differential 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 LTC6419 is stable in a differential gain of 1. This al-
lows for low output noise in applications where gain is not
desired. Each amplifier draws 52mA of supply current and
has an independent shutdown pin which reduces current
consumption to 100µA per amplifier.
The LTC6419 is available in a compact 4mm × 3mm
20-pin LQFN 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 Analog
Devices, Inc. All other trademarks are the property of their respective owners.
10GHz Gain-Bandwidth Product
85dB SFDR at 100MHz, 2V
P-P
1.1nV/√Hz Input Noise Density
Channel Separation 95dB at 100MHz
Input Range Includes Ground
External Resistors Set Gain (Min 1V/V)
3300V/µs Differential Slew Rate
52mA Supply Current (Per Amplifier)
2.7V to 5.25V Supply Voltage Range
Fully Differential Input and Output
Adjustable Output Common Mode Voltage
Low Power Shutdown
Small 20-Lead 4mm × 3mm × 0.75mm LQFN Package
APPLICATIONS
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Broadband I/Q Amplifiers
Dual Differential ADC Driver
High-Speed Data-Acquisition Cards
Automated Test Equipment
Time Domain Reflectometry
Communications Receivers
TYPICAL APPLICATION
DC-Coupled Interface from a Ground-Referenced Single-Ended
Input to an LTC2175-14 ADC
1.3pF
V
IN
1/2 LTC6419 Driving 1/4 LTC2175-14
ADC, f
IN
= 45MHz, –1dBFS,
f
S
= 125MHz, 32768-Point FFT
0
V
S
= 3.3V
–10 V
OUTDIFF
= 1.8V
P-P
–20 HD2 = –86.8dBc
HD3 = –86.5dBc
–30
SFDR = 86.5dB
–40 SNR = 71.8dB
–50
–60
–70
–80
–90
–100
–110
–120
0
10
20
30
40
FREQUENCY (MHz)
50
60
6419 TA01b
150
150
1.8V
3.3V
39pF
33.2
10
A
IN+
A
IN–
V
DD
AMPLITUDE (dBFS)
– +
V
OCM
= 0.9V
1/2 LTC6419
+ –
150
150
33.2
10
39pF
1/4 LTC2175-14 ADC
GND
6419 TA01
1.3pF
6419fa
For more information
www.linear.com/LTC6419
1
LTC6419
ABSOLUTE MAXIMUM RATINGS
(Note 1)
PIN CONFIGURATION
TOP VIEW
–OUTA
17
16
21
V
–
21
V
–
15
14
13
12
11
7
+INB
8
–FBB
9
V
OCMB
10
–OUTB
+OUTA
V
+
A
V
–
V
–
V
+
B
+OUTB
V
OCMA
18
21
V
–
–FBA
19
21
V
–
+INA
20
–INA
+FBA
SHDNA
SHDNB
+FBB
–INB
1
2
3
4
5
6
Total Supply Voltage (V
+
A – V
–
), (V
+
B – V
–
) ............5.5V
Input Current (+INA, –INA, +INB, –INB,
V
OCMA
, V
OCMB
,
SHDNA, SHDNB)
(Note 2) ........... ±10mA
Output Current (Note 13) ................................ 50mA
RMS
Output Short-Circuit Duration
(Note 3) ...............................................Thermally Limited
Temperature Range (Notes 4, 5)
LTC6419I .............................................–40°C to 85°C
LTC6419H .......................................... –40°C to 125°C
Maximum Junction Temperature .......................... 150°C
Storage Temperature Range .................. –65°C to 150°C
Maximum Reflow (Package Body) Temperature ..... 260°C
LQFN PACKAGE
20-LEAD (4mm
×
3mm
×
0.75mm)
T
JMAX
= 150°C,
θ
JA
= 44°C/W,
θ
JC
= 12°C/W
EXPOSED PADS (PIN 21) CONNECTED TO V
–
ORDER INFORMATION
PART NUMBER
LTC6419IV#PBF
LTC6419HV#PBF
PART MARKING*
6419
6419
http://www.linear.com/product/LTC6419#orderinfo
FINISH CODE
e4
PAD FINISH
Au (RoHS)
PACKAGE**
TYPE
LQFN
MSL
RATING
3
TEMPERATURE RANGE
–40°C to 85°C
–40°C to 125°C
• Consult Marketing for parts specified with wider operating temperature ranges.
Pad or ball finish code is per IPC/JEDEC J-STD-609. *The temperature grade is
identified by a label on the shipping container.
• Terminal Finish Part Marking:
www.linear.com/leadfree
• Recommended PCB Assembly and Manufacturing Procedures:
www.linear.com/umodule/pcbassembly
• Package and Tray Drawings:
www.linear.com/packaging
Parts ending with PBF are RoHS and WEEE compliant. **The LTC6419 is a laminate package with the same dimensions as a standard 4mm × 3mm × 0.75mm
QFN package.
6419fa
2
For more information
www.linear.com/LTC6419
LTC6419
ELECTRICAL CHARACTERISTICS
SYMBOL PARAMETER
V
OSDIFF
Differential Offset Voltage (Input Referred)
The
l
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
+
= V
+
A = V
+
B = 5V, V
–
= 0V, V
CM
= V
ICM
= V
OCMA
= V
OCMB
= 1.25V,
V
SHDNA
= V
SHDNB
= 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
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
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
l
MIN
TYP
±300
±300
MAX
±1000
±1200
±1100
±1400
UNITS
µV
µV
µV
µV
µV/°C
µV/°C
l
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l
ΔV
OSDIFF
Differential Offset Voltage Drift (Input Referred)
ΔT
I
B
I
OS
R
IN
C
IN
e
n
i
n
e
nVOCM
V
ICMR
(Note 7)
CMRRI
(Note 8)
Input Bias Current (Note 6)
Input Offset Current (Note 6)
Input Resistance
Input Capacitance
Differential Input Noise Voltage Density
Input Noise Current Density
Common Mode Noise Voltage Density
Input Signal Common Mode Range
Input Common Mode Rejection Ratio
(Input Referred) ΔV
ICM
/ΔV
OSDIFF
2
2
–140
–160
–62
–70
±2
±2
165
860
0.5
1.1
8.8
12
0
0
75
75
55
60
60
55
2.7
1
1
±0.1
±0.1
–65
–70
±1
±1
4
0.5
0.5
30
0.9
40
0.85
1.25
1.5
3.5
50
1.6
±0.3
±0.3
–50
–50
±5
±6
90
90
80
85
85
70
5.25
1.5
3.5
0
0
±10
±10
µA
µA
µA
µA
kΩ
Ω
pF
nV/√Hz
pA/√Hz
nV/√Hz
V
V
dB
dB
dB
dB
dB
dB
V
V/V
V/V
%
%
dB
dB
mV
mV
µV/°C
V
V
KΩ
V
V
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
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
l
l
l
l
l
l
l
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V
OSCM
ΔV
OSCM
ΔT
V
OUTCMR
Output Signal Common Mode Range
(Note 7) (Voltage Range for the V
OCMA
/V
OCMB
Pins)
R
INVOCM
Input Resistance, V
OCMA
/V
OCMB
Pins
V
OCM
Self-Biased Voltage at the V
OCMA
/V
OCMB
Pins
V
S
= 3V
V
S
= 5V
V
S
= 3V, V
OCMA
= V
OCMB
= Open
V
S
= 5V, V
OCMA
= V
OCMB
= Open
l
l
l
l
6419fa
For more information
www.linear.com/LTC6419
3
LTC6419
ELECTRICAL CHARACTERISTICS
SYMBOL PARAMETER
V
OUT
Output Voltage, High, Either Output Pin
The
l
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
+
= V
+
A = V
+
B = 5V, V
–
= 0V, V
CM
= V
ICM
= V
OCMA
= V
OCMB
= 1.25V,
V
SHDNA
= V
SHDNB
= 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
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
MIN
1.85
1.8
3.85
3.8
TYP
2
1.95
4
3.95
0.06
0.2
MAX
UNITS
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
SR
Output Short-Circuit Current, Either Output Pin
(Note 11)
Large-Signal Open Loop Voltage Gain
Supply Current (Per Amplifier)
0.15
0.4
V
V
mA
mA
dB
±50
±70
±70
±95
65
52
56
58
500
185
0.6
l
mA
mA
µA
KΩ
V
V
ns
ns
V/µs
V/µs
V/µs
GHz
GHz
GHz
MHz
MHz
dB
Supply Current in Shutdown (Per Amplifier)
SHDNA/SHDNB
Pull-Up Resistor
SHDNA/SHDNB
Input Logic Low
SHDNA/SHDNB
Input Logic High
Turn-On Time
Turn-Off Time
Slew Rate
V
SHDNA
= V
SHDNB
≤ 0.6V
V
SHDNA
= V
SHDNB
= 0V to 0.5V
l
l
l
l
100
115
1.4
160
80
150
Differential Output, V
OUTDIFF
= 4V
P-P
+OUTA/+OUTB Rising (–OUTA/–OUTB Falling)
+OUTA/+OUTB Falling (–OUTA/–OUTB Rising)
R
I
= 25Ω, R
F
= 10kΩ, f
TEST
= 100MHz
l
3300
1720
1580
9.5
8
10
1.4
320
550
95
GBW
f
–3dB
f
0.1dB
FPBW
HD2
HD3
Gain-Bandwidth Product
–3dB Frequency
Frequency for 0.1dB Flatness
Full Power Bandwidth
Channel Separation (Note 12)
25MHz Distortion
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
f = 100MHz
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
–82
–106
dBc
dBc
100MHz Distortion
–85
–85
dBc
dBc
HD2
HD3
25MHz Distortion
–96
–105
dBc
dBc
100MHz Distortion
–83
–85
dBc
dBc
6419fa
4
For more information
www.linear.com/LTC6419
LTC6419
The
l
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
+
= V
+
A = V
+
B = 5V, V
–
= 0V, V
CM
= V
ICM
= V
OCMA
= V
OCMB
= 1.25V,
V
SHDNA
= V
SHDNB
= 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
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
t
S
Settling Time
CONDITIONS
V
OUTDIFF
= 1V
P-P
per Tone, R
I
= R
F
= 150Ω,
R
LOAD
= 400Ω
V
OUTDIFF
= 1V
P-P
per Tone, R
I
= R
F
= 150Ω,
R
LOAD
= 400Ω
V
OUTDIFF
= 1V
P-P
per Tone, R
I
= R
F
= 150Ω,
R
LOAD
= 400Ω
V
OUTDIFF
= 2V
P-P
Step, R
I
= R
F
= 150Ω,
R
LOAD
= 400Ω
1% Settling
MIN
TYP
–103
–87
–77
MAX
UNITS
dBc
dBc
dBc
ELECTRICAL CHARACTERISTICS
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 (+INA, –INA, +INB, –INB, V
OCMA
, V
OCMB
,
SHDNA,
SHDNB)
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 (+INA/–INA or +INB/–INB) 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 LTC6419I is guaranteed functional over the temperature
range of –40°C to 85°C. The LTC6419H is guaranteed functional over the
temperature range of –40°C to 125°C.
Note 5:
The LTC6419I is guaranteed to meet specified performance
from –40°C to 85°C. The LTC6419H 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 (–INA/+INA or –INB/+INB). Input offset current is
defined as the difference between the input currents (I
OS
= I
B+
– I
B–
).
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 (+INA/–INA or +INB/–INB) 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
OCMA
or V
OCMB
pins 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:
Channel separation (the inverse of crosstalk) is measured by
driving a signal into one input, while terminating the other input. Channel
separation is the ratio of the resulting output signal at the driven channel
to the channel that is not driven.
Note 13:
The LTC6419 is capable of producing peak output currents in
excess of 50mA. Current density limitations within the IC require the
continuous RMS current supplied by the output (sourcing or sinking)
over the operating lifetime of the part be limited to under 50mA (Absolute
Maximum). Proper heat sinking may be required to keep the junction
temperature below the absolute maximum rating.
6419fa
For more information
www.linear.com/LTC6419
5
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