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PDF LTC6419 Data sheet ( Hoja de datos )
| Número de pieza | LTC6419 | |
| Descripción | Differential Amplifier/ADC Driver | |
| Fabricantes | Linear Technology | |
| Logotipo |  |
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Hay una vista previa y un enlace de descarga de LTC6419 (archivo pdf) en la parte inferior de esta página. Total 22 Páginas | ||
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FEATURES
n 10GHz Gain-Bandwidth Product
n 85dB SFDR at 100MHz, 2VP-P
n 1.1nV/√Hz Input Noise Density
n Channel Separation 95dB at 100MHz
n Input Range Includes Ground
n External Resistors Set Gain (Min 1V/V)
n 3300V/µs Differential Slew Rate
n 52mA Supply Current (Per Amplifier)
n 2.7V to 5.25V Supply Voltage Range
n Fully Differential Input and Output
n Adjustable Output Common Mode Voltage
n Low Power Shutdown
n Small 20-Lead 4mm × 3mm × 0.75mm LGA Package
APPLICATIONS
n Broadband I/Q Amplifiers
n Dual Differential ADC Driver
n High-Speed Data-Acquisition Cards
n Automated Test Equipment
n Time Domain Reflectometry
n Communications Receivers
LTC6419
Dual 10GHz GBW,
1.1nV/√Hz Differential
Amplifier/ADC Driver
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 LGA 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.
TYPICAL APPLICATION
DC-Coupled Interface from a Ground-Referenced Single-Ended
Input to an LTC2175-14 ADC
1.3pF
VIN 150Ω
VOCM = 0.9V
150Ω
150Ω
3.3V
–+
1/2 LTC6419
+–
150Ω
1.3pF
33.2Ω
33.2Ω
39pF
10Ω
10Ω
39pF
1.8V
AIN+ VDD
1/4 LTC2175-14 ADC
AIN– GND
6419 TA01
For more information www.linear.com/LTC6419
1/2 LTC6419 Driving 1/4 LTC2175-14
ADC, fIN = 45MHz, –1dBFS,
fS = 125MHz, 32768-Point FFT
0
–10
VS = 3.3V
VOUTDIFF = 1.8V P-P
–20 HD2 = –86.8dBc
–30
HD3 = –86.5dBc
SFDR = 86.5dB
–40 SNR = 71.8dB
–50
–60
–70
–80
–90
–100
–110
–120
0
10 20 30 40 50 60
FREQUENCY (MHz)
6419 TA01b
6419f
1
1 page  
ELECTRICAL CHARACTERISTICS
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 VOCMA or VOCMB 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.
LTC6419
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.
TYPICAL PERFORMANCE CHARACTERISTICS
Differential Input Offset Voltage
vs Temperature
1.5
1.0
0.5 VS = 5V
VOCM = VICM = 1.25V
RI = RF = 150Ω
FIVE REPRESENTATIVE UNITS
0
–0.5
–50 –25
0 25 50 75
TEMPERATURE (°C)
100 125
6419 G01
Differential Input Offset Voltage
vs Input Common Mode Voltage
2.0 VS = 5V
VOCM = 1.25V
1.5 RI = RF = 150Ω
0.1% FEEDBACK NETWORK RESISTORS
REPRESENTATIVE UNIT
1.0
0.5
0
–0.5
–1.0
0
TA = 85°C
TA = 70°C
TA = 25°C
TA = 0°C
TA = –40°C
0.5 1 1.5 2 2.5 3 3.5 4
INPUT COMMON MODE VOLTAGE (V)
6419 G02
Supply Current (per Amplifier) vs
Supply Voltage
60
55
VSHDN = OPEN
50
45
40
35
30
25
20
15
TA = 125°C
TA = 85°C
TA = 70°C
10 TA = 25°C
5
0
TA = 0°C
TA = –40°C
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5
SUPPLY VOLTAGE (V)
6419 G04
Supply Current (per Amplifier) vs
SHDN Voltage
60
55
VS = 5V
50
45
40
35
30
25
20
15
TA = 125°C
TA = 85°C
TA = 70°C
10 TA = 25°C
5
0
TA = 0°C
TA = –40°C
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5
SHDN VOLTAGE (V)
6419 G05
For more information www.linear.com/LTC6419
Common Mode Offset Voltage
vs Temperature
2.5
2.0
1.5
VS = 5V
VOCM = VICM = 1.25V
RI = RF = 150Ω
1.0 FIVE REPRESENTATIVE UNITS
0.5
0
–0.5
–50 –25
0 25 50 75
TEMPERATURE (°C)
100 125
6419 G03
Shutdown Supply Current (per
Amplifier) vs Supply Voltage
140 TA = 125°C
120
TA = 85°C
TA = 70°C
TA = 25°C
100 TA = 0°C
TA = –40°C
80
60
40
20
0 VSHDN = V–
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5
SUPPLY VOLTAGE (V)
6419 G06
6419f
5
5 Page 
LTC6419
APPLICATIONS INFORMATION
capable of driving the 40k input resistance presented by the
VOCM pin. The Electrical Characteristics table specifies the
valid range that can be applied to the VOCM pin (VOUTCMR).
Input Common Mode Voltage Range
The LTC6419’s input common mode voltage (VICM) is
defined as the average of the two input pins, V+IN and
V–IN. The valid range that can be used for VICM has been
specified in the Electrical Characteristics table (VICMR).
However, due to external resistive divider action of the
gain and feedback resistors, the effective range of signals
that can be processed is even wider. The input common
mode range at the op amp inputs depends on the circuit
configuration (gain), VOCM and VCM (refer to Figure 1). For
fully differential input applications, where VINP = –VINM,
the common mode input is approximately:
VICM
=
V+IN
+
2
V–IN
≈
VOCM
•
RI
RI + RF
+
VCM
•
RF
RI + RF
With single-ended inputs, there is an input signal com-
ponent to the input common mode voltage. Applying
only VINP (setting VINM to zero), the input common mode
voltage is approximately:
VICM
=
V+IN
+
2
V–IN
≈
VOCM
•
RI
RI + RF
+
VCM
•
RI
RF
+ RF
+
VINP
2
•
RF
RI + RF
(2)
This means that if, for example, the input signal (VINP)
is a sine, an attenuated version of that sine signal also
appears at the op amp inputs.
Input Impedance and Loading Effects
The low frequency input impedance looking into the VINP
or VINM input of Figure 1 depends on how the inputs are
driven. For fully differential input sources (VINP = –VINM),
the input impedance seen at either input is simply:
RINP = RINM = RI
For single-ended inputs, because of the signal imbalance
at the input, the input impedance actually increases over
the balanced differential case. The input impedance looking
into either input is:
RINP
=
RINM
=
1–
1
2
RI
•
RF
RI + RF
Input signal sources with non-zero output impedances can
also cause feedback imbalance between the pair of feedback
networks. For the best performance, it is recommended
that the input source output impedance be compensated.
If input impedance matching is required by the source, a
termination resistor RT should be chosen (see Figure 2)
such that:
RT
=
RINM
RINM
• RS
– RS
According to Figure 2, the input impedance looking into
the differential amp (RINM) reflects the single-ended source
case, given above. Also, R2 is chosen as:
R2
=
RT
||RS
=
RT
RT
• RS
+ RS
RINM
RS RI RF
VS RT
RT CHOSEN SO THAT RT || RINM = RS
R2 CHOSEN TO BALANCE RT || RS
RI
R2 = RS || RT
–+
+–
RF
6419 F02
Figure 2. Optimal Compensation for Signal Source Impedance
Effects of Resistor Pair Mismatch
Figure 3 shows a circuit diagram which takes into consid-
eration that real world resistors will not match perfectly.
For more information www.linear.com/LTC6419
6419f
11
11 Page | ||
| Páginas | Total 22 Páginas | |
| PDF Descargar | [ Datasheet LTC6419.PDF ] | |
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