FEATURES
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LT6411
650MHz Differential ADC
Driver/Dual Selectable
Gain Amplifier
DESCRIPTION
The LT
®
6411 is a dual amplifier with individually selectable
gains of +1, +2 and –1. The amplifiers have excellent dis-
tortion performance for driving ADCs as well as excellent
bandwidth and slew rate for video, data transmission and
other high speed applications. Single-ended to differential
conversion with a system gain of 2 is particularly straight-
forward by configuring one amplifier with a gain of +1
and the other amplifier with a gain of –1. The LT6411 can
be used on split supplies as large as ±6V and on a single
supply as low as 4.5V.
Each amplifier draws only 8mA of quiescent current when
enabled. When disabled, the output pins become high
impedance and each amplifier draws less than 350µA.
The LT6411 is manufactured on Linear Technology’s
proprietary, low voltage, complimentary, bipolar process
and is available in the ultra-compact, 3mm
×
3mm, 16pin
QFN package.
, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
650MHz –3dB Small-Signal Bandwidth
600MHz –3dB Large-Signal Bandwidth
High Slew Rate: 3300V/µs
Easily Configured for Single-Ended to Differential
Conversion
200MHz ±0.1dB Bandwidth
User Selectable Gain of +1, +2 and –1
No External Resistors Required
46.5dBm Equivalent OIP3 at 30MHz When Driving an
ADC
IM3 with 2V
P-P
Composite, Differential Output:
–87dBc at 30MHz, –83dBc at 70MHz
–77dB SFDR at 30MHz, 2V
P-P
Differential Output
6ns 0.1% Settling Time for 2V Step
Low Supply Current: 8mA per Ampifier
Differential Gain of 0.02%, Differential Phase of 0.01°
50dB Channel Separation at 100MHz
Wide Supply Range: ±2.25V (4.5V) to ±6.3V (12.6V)
3mm
×
3mm 16-Pin QFN Package
APPLICATIONS
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Differential ADC Driver
Single-Ended to Differential Conversion
Differential Video Line Driver
TYPICAL APPLICATION
Differential ADC Driver
5V
V
CC
LT6411
30MHz 2-Tone 32768 Point FFT, LT6411
Driving an LTC
®
2249 14-Bit ADC
0
–10
–20
–30
–40
–50
–60
–70
–80
–90
–100
–110
–120
–130
–140
0
32768 POINT FFT
TONE 1 AT 29.5MHz, –7dBFS
TONE 2 AT 30.5MHz, –7dBFS
IM3 = –87dBc
1.9V
DC
370Ω
30MHz
INPUT
1.9V
DC
370Ω
+
–
370Ω
370Ω
24Ω
A
IN–
LTC2249
14-BIT ADC
80Msps
A
IN+
6411 TA01a
–
+
DGND
EN
V
EE
24Ω
AMPLITUDE (dBFS)
5
10
15 20 25 30
FREQUENCY (MHz)
35
40
6411 TA01b
6411f
1
LT6411
ABSOLUTE MAXIMUM RATINGS
(Note 1)
PACKAGE/ORDER INFORMATION
TOP VIEW
IN2
+
IN2
–
15
Total Supply Voltage (V
CC
to V
EE
) ..........................12.6V
Input Current (Note 2)..........................................±10mA
Output Current (Continuous) ...............................±70mA
EN to DGND Voltage (Note 2) ..................................5.5V
Output Short-Circuit Duration (Note 3) ............ Indefinite
Operating Temperature Range (Note 4) ... –40°C to 85°C
Specified Temperature Range (Note 5) .... –40°C to 85°C
Storage Temperature Range................... –65°C to 125°C
Junction Temperature ........................................... 125°C
IN1
–
14
16
V
EE 1
V
EE 2
V
EE 3
NC
4
5
6
7
8
17
IN1
+
13
12
DGND
11
EN
10
V
CC
9
V
CC
OUT2
UD PACKAGE
16-LEAD (3mm
×
3mm) PLASTIC QFN
T
JMAX
= 125°C,
θ
JA
= 68°C/W,
θ
JC
= 4.2°C/W
EXPOSED PAD (PIN 17) IS V
EE
, MUST BE SOLDERED TO PCB
ORDER PART NUMBER
LT6411CUD
LT6411IUD
OUT1
V
CC
V
EE
UD PART MARKING*
LCGP
LCGP
Order Options
Tape and Reel: Add #TR
Lead Free: Add #PBF Lead Free Tape and Reel: Add #TRPBF
Lead Free Part Marking:
http://www.linear.com/leadfree/
Consult LTC Marketing for parts specified with wider operating temperature ranges.
*Temperature grade is identified by a label on the shipping container.
ELECTRICAL CHARACTERISTICS
SYMBOL
V
OS
I
IN
R
IN
C
IN
V
CMR
PSRR
I
PSRR
A
V
ERR
A
V
MATCH
V
OUT
PARAMETER
Input Referred Offset Voltage
Input Current
Input Resistance
Input Capacitance
Maximum Input Common Mode Voltage
Minimum Input Common Mode Voltage
Power Supply Rejection Ratio
Input Current Power Supply Rejection
Gain Error
Gain Matching
Maximum Output Voltage Swing
The
●
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
S
= ±5V, A
V
= 2, R
L
= 150Ω, C
L
= 1.5pF, V
EN
= 0.4V, V
DGND
= 0V,
unless otherwise noted.
CONDITIONS
V
IN
= 0V, V
OS
= V
OUT
/2
●
●
●
MIN
TYP
3
–17
MAX
±10
±20
±50
UNITS
mV
mV
µA
kΩ
pF
V
V
dB
V
IN
= ±1V
f = 100kHz
150
500
1
V
CC
– 1
V
EE
+ 1
V
S
(Total) = 4.5V to 12V (Note 6)
V
S
(Total) = 4.5V to 12V (Note 6)
V
OUT
= ±2V
V
OUT
= ±2V
R
L
= 1k
R
L
= 150Ω
R
L
= 150Ω
●
●
●
56
62
1
–1.2
±1
±4
±5
µA/V
%
%
V
V
V
●
●
±3.70
±3.25
±3.10
±3.95
±3.6
8
22
0.5
11
14
350
350
50
I
S
Supply Current, Per Amplifier
Supply Current, Disabled, per Amplifier
V
EN
= 4V
V
EN
= Open
V
EN
= 0.4V
V
EN
= V
+
mA
mA
µA
µA
µA
µA
6411f
●
●
●
●
I
EN
Enable Pin Current
–200
–95
0.5
2
LT6411
ELECTRICAL CHARACTERISTICS
SYMBOL
I
SC
SR
–3dB BW
0.1dB BW
FPBW
PARAMETER
Output Short-Circuit Current
Slew Rate
Small-Signal –3dB Bandwidth
Gain Flatness ±0.1dB Bandwidth
Full Power Bandwidth 2V Differential
Full Power Bandwidth 2V
Full Power Bandwidth 4V
All Hostile Crosstalk
t
s
t
r
, t
f
dG
dP
Settling Time
Small-Signal Rise and Fall Time
Differential Gain
Diffierential Phase
The
●
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
S
= ±5V, A
V
= 2, R
L
= 150Ω, C
L
= 1.5pF, V
EN
= 0.4V, V
DGND
= 0V,
unless otherwise noted.
CONDITIONS
R
L
= 0Ω, V
IN
= ±1V
±1V on ±2V Output Step (Note 9)
V
OUT
= 200mV
P-P
, Single Ended
V
OUT
= 200mV
P-P
, Single Ended
V
OUT
= 2V
P-P
Differential, –3dB
V
OUT
= 2V
P-P
(Note 7)
V
OUT
= 4V
P-P
(Note 7)
f = 10MHz, V
OUT
= 2V
P-P
f = 100MHz, V
OUT
= 2V
P-P
0.1% to V
FINAL
, V
STEP
= 2V
10% to 90%, V
OUT
= 200mV
P-P
(Note 8)
(Note 8)
270
●
MIN
±50
1700
TYP
±105
3300
650
200
600
525
263
–75
–50
6
550
0.02
0.01
MAX
UNITS
mA
V/µs
MHz
MHz
MHz
MHz
MHz
dB
dB
ns
ps
%
Deg
The
●
denotes the specifications which apply over the full operating temperature range, otherwise specifications are at T
A
= 25°C.
V
CC
= 5V, V
EE
= 0V, A
V
= 2, No R
LOAD
, V
EN
= 0.4V, V
DGND
= 0V, unless otherwise noted.
SYMBOL
1MHz Signal
HD
IMD3
1M
Second/Third Harmonic Distortion
Third-Order IMD
2V
P-P
Differential
2V
P-P
Differential, R
L
= 200Ω Differential
2V
P-P
Differential Composite, f1 = 0.95MHz,
f2 = 1.05MHz
2V
P-P
Differential Composite, f1 = 0.95MHz,
f2 = 1.05MHz, R
L
= 200Ω Differential
OIP3
1M
NF
e
n1M
P1dB
HD
IMD3
10M
Output Third-Order Intercept
Noise Figure
Input Referred Noise Voltage Density
1dB Compression Point
Second/Third Harmonic Distortion
Third-Order IMD
(Note 10)
2V
P-P
Differential
2V
P-P
Differential, R
L
= 200Ω Differential
2V
P-P
Differential Composite, R
L
= 1k,
f1 = 9.5MHz, f2 = 10.5MHz
2V
P-P
Differential Composite, f1 = 9.5MHz,
f2 = 10.5MHz, R
L
= 200Ω Differential
OIP3
10M
NF
e
n10M
P1dB
Output Third-Order Intercept
Noise Figure
Input Referred Noise Voltage Density
1dB Compression Point
(Note 10)
Differential, f1 = 9.5MHz, f2 = 10.5MHz (Note 10)
Single Ended
Differential, f1 = 0.95MHz, f2 = 1.05MHz (Note 10)
Single Ended
–88
–87
–93
–91
49.5
25.1
8
19.5
–85
–76
–92
–89
49
24.7
7.7
19.5
dBc
dBc
dBc
dBc
dBm
dB
nV/√Hz
dBm
dBc
dBc
dBc
dBc
dBm
dB
nV/√Hz
dBm
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
Noise/Harmonic Performance Input/Output Characteristics
10MHz Signal
6411f
3
LT6411
ELECTRICAL CHARACTERISTICS
SYMBOL
HD
IMD3
30M
PARAMETER
Second/Third Harmonic Distortion
Third-Order IMD
30MHz Signal
2V
P-P
Differential
2V
P-P
Differential, R
L
= 200Ω Differential
2V
P-P
Differential Composite, f1 = 29.5MHz,
Differential, f2 = 30.5MHz
2V
P-P
Differential Composite, f1 = 29.5MHz,
f2 = 30.5MHz, R
L
= 200Ω Differential
OIP3
30M
NF
e
n30M
P1dB
HD
IMD3
70M
Output Third-Order Intercept
Noise Figure
Input Referred Noise Voltage Density
1dB Compression Point
Second/Third Harmonic Distortion
Third-Order IMD
(Note 10)
2V
P-P
Differential
2V
P-P
Differential, R
L
= 200Ω Differential
2V
P-P
Differential Composite, f1 = 69.5MHz,
Differential, f2 = 70.5MHz
2V
P-P
Differential Composite, f1 = 69.5MHz,
f2 = 70.5MHz, R
L
= 200Ω Differential
OIP3
70M
NF
e
n70M
P1dB
Output Third-Order Intercept
Noise Figure
Input Referred Noise Voltage Density
1dB Compression Point
(Note 10)
Differential, f1 = 69.5MHz, f2 = 70.5MHz (Note 10)
Single Ended
Differential, f1 = 29.5MHz, f2 = 30.5MHz (Note 10)
Single Ended
–77
–64
–87
–75
46.5
24.6
7.6
19.5
–63
–52
–83
–64
44.5
24.7
7.7
19.5
dBc
dBc
dBc
dBc
dBm
dB
nV/√Hz
dBm
dBc
dBc
dBc
dBc
dBm
dB
nV/√Hz
dBm
The
●
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
CC
= 5V, V
EE
= 0V, A
V
= 2, No R
LOAD
, V
EN
= 0.4V, V
DGND
= 0V,
unless otherwise noted.
CONDITIONS
MIN
TYP
MAX
UNITS
70MHz Signal
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:
This parameter is guaranteed to meet specified performance
through design and characterization. It is not production tested.
Note 3:
As long as output current and junction temperature are kept
below the Absolute Maximum Ratings, no damage to the part will occur.
Depending on the supply voltage, a heat sink may be required.
Note 4:
The LT6411C is guaranteed functional over the operating
temperature range of –40°C to 85°C.
Note 5:
The LT6411C is guaranteed to meet specified performance from
0°C to 70°C. The LT6411C is designed, characterized and expected to
meet specified performance from –40°C and 85°C but is not tested or
QA sampled at these temperatures. The LT6411I is guaranteed to meet
specified performance from –40°C to 85°C.
Note 6:
The two supply voltage settings for power supply rejection
are shifted from the typical ±V
S
points for ease of testing. The first
measurement is taken at V
CC
= 3V, V
EE
= –1.5V to provide the required 3V
headroom for the enable circuitry to function with EN, DGND and all inputs
connected to 0V. The second measurement is taken at V
CC
= 8V, V
EE
= –4V.
Note 7:
Full power bandwidth is calculated from the slew rate:
FPBW = SR/(π • V
P-P
)
Note 8:
Differential gain and phase are measured using a Tektronix
TSG120YC/NTSC signal generator and a Tektronix 1780R video
measurement set. The resolution of this equipment is better than 0.05%
and 0.05°. Ten identical amplifier stages were cascaded giving an effective
resolution of better than 0.005% and 0.005°.
Note 9:
Slew rate is 100% production tested on channel 1. Slew rate of
channel 2 is guaranteed through design and characterization.
Note 10:
Since the LT6411 is a feedback amplifier with low output
impedance, a resistive load is not required when driving an ADC.
Therefore, typical output power is very small. In order to compare the
LT6411 with typical g
m
amplifiers that require 50Ω output loading, the
LT6411 output voltage swing driving an ADC is converted to OIP3 and
P1dB as if it were driving a 50Ω load.
6411f
4
LT6411
TYPICAL PERFORMANCE CHARACTERISTICS
All measurements are per amplifier with single-ended outputs unless otherwise noted.
Supply Current per Amplifier
vs Temperature
12
10
SUPPLY CURRENT (mA)
8
6
4
2
0
–55 –35 –15
V
EN
= 0V
V
EN
= 0.4V
V
S
=
±5V
R
L
=
∞
V
IN+
, V
IN–
= 0V
SUPPLY CURRENT (mA)
12
Supply Current per Ampifier
vs Supply Voltage
V
CC
= –V
EE
V
EN
, V
DGND
, V
IN+
, V
IN–
= 0V
10 T
A
= 25°C
SUPPLY CURRENT (mA)
8
6
4
2
0
12
10
8
6
4
2
0
0
1
2
3 4 5 6 7 8 9 10 11 12
TOTAL SUPPLY VOLTAGE (V)
6411 G02
Supply Current per Amplifier
vs EN Pin Voltage
V
S
=
±5V
V
DGND
= 0V
V
IN+
, V
IN–
= 0V
T
A
= –55°C
T
A
= 25°C
T
A
= 125°C
5 25 45 65
TEMPERATURE (°C)
85 105 125
6411 G01
0
0.5
1.0 1.5 2.0 2.5 3.0
EN PIN VOLTAGE (V)
3.5
4.0
6411 G03
Output Offset Voltage
vs Temperature
20
V
S
=
±5V
15 V
IN
= 0V
A
V
= 2
10
5
0
–5
–10
–15
–20
–55 –35 –15
5 25 45 65 85 105 125
TEMPERATURE (°C)
6411 G04
Positive Input Bias Current
vs Input Voltage
20
V
S
=
±5V
A
V
= 2
EN PIN CURRENT (µA)
T
A
= 125°C
–20
0
–20
–40
–60
–80
EN Pin Current vs EN Pin Voltage
V
S
=
±5V
V
DGND
= 0V
IN
+
BIAS CURRENT (µA)
OFFSET VOLTAGE (mV)
0
T
A
= 125°C
T
A
= –55°C
T
A
= 25°C
T
A
= 25°C
T
A
= –55°C
–40
–100
–120
–60
–2.5
–1.5
0.5
–0.5
INPUT VOLTAGE (V)
1.5
2.5
6411 G05
–140
0
1
3
2
EN PIN VOLTAGE (V)
4
5
6411 G06
Output Voltage vs Input Voltage
5
V
S
=
±5V
4 R
L
= 1k
A
V
= 1
3
OUTPUT VOLTAGE (V)
OUTPUT VOLTAGE (V)
2
1
0
–1
–2 T
A
= –55°C
–3
–4
T
A
= 125°C
–5
–4.5 –3.5 –2.5 –1.5 –0.5 0.5 1.5 2.5 3.5 4.5
INPUT VOLTAGE (V)
6411 G07
Output Voltage Swing vs I
LOAD
(Output High)
5
V
S
=
±5V
A
V
= 2
V
IN
= 2V
OUTPUT VOLTAGE (V)
T
A
= –55°C
T
A
= 25°C
2
T
A
= 125°C
1
0
Output Voltage Swing vs I
LOAD
(Output Low)
V
S
=
±5V
A
V
= 2
V
IN
= –2V
T
A
= 25°C
–2
T
A
= 125°C
–3
T
A
= –55°C
4
T
A
= 25°C
–1
3
–4
0
0
10 20 30 40 50 60 70 80 90 100
SOURCE CURRENT (mA)
6411 G08
–5
0
10 20 30 40 50 60 70 80 90 100
SINK CURRENT (mA)
6411 G09
6411f
5
