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PDF LT1993-10 Data sheet ( Hoja de datos )
| Número de pieza | LT1993-10 | |
| Descripción | 700MHz Low Distortion - Low Noise Differential Amplifier/ADC Driver | |
| Fabricantes | Linear Technology | |
| Logotipo |  |
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FEATURES
■ 700MHz –3dB Bandwidth
■ Fixed Gain of 10V/V (20dB)
■ Low Distortion:
40dBm OIP3, –70dBc HD3 (70MHz 2VP-P)
50.5dBm OIP3, –91dBc (10MHz 2VP-P)
■ Low Noise: 12.7dB NF, en = 1.9nV/√Hz
■ Differential Inputs and Outputs
■ Additional Filtered Outputs
■ Adjustable Output Common Mode Voltage
■ DC- or AC-Coupled Operation
■ Minimal Support Circuitry Required
■ Small 0.75mm Tall 16-Lead 3 × 3 QFN Package
U
APPLICATIO S
■ Differential ADC Driver for:
Imaging
Communications
■ Differential Driver/Receiver
■ Single Ended to Differential Conversion
■ Differential to Single Ended Conversion
■ Level Shifting
■ IF Sampling Receivers
■ SAW Filter Interfacing/Buffering
, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
LT1993-10www.DataSheet4U.com
700MHz Low Distortion, Low
Noise Differential Amplifier/
ADC Driver (AV = 10V/V)
DESCRIPTIO
The LT®1993-10 is a low distortion, low noise Differential
Amplifier/ADC driver for use in applications from DC to
700MHz. The LT1993-10 has been designed for ease of
use, with minimal support circuitry required. Exception-
ally low input-referred noise and low distortion products
(with either single-ended or differential inputs) make the
LT1993-10 an excellent solution for driving high speed
12-bit and 14-bit ADCs. In addition to the normal unfiltered
outputs (+OUT and –OUT), the LT1993-10 has a built-in
175MHz differential lowpass filter and an additional pair
of filtered outputs (+OUTFILTERED, –OUTFILTERED) to
reduce external filtering components when driving high
speed ADCs. The output common mode voltage is easily set
via the VOCM pin, eliminating either an output transformer
or AC-coupling capacitors in many applications.
The LT1993-10 is designed to meet the demanding require-
ments of communications transceiver applications. It can
be used as a differential ADC driver, a general-purpose
differential gain block, or in any other application requir-
ing differential drive. The LT1993-10 can be used in data
acquisition systems required to function at frequencies
down to DC.
The LT1993-10 operates on a 5V supply and consumes
100mA. It comes in a compact 16-lead 3 × 3 QFN package
and operates over a –40°C to 85°C temperature range.
TYPICAL APPLICATIO
4-Channel WCDMA Receive Channel
70MHz
IF IN
1:1
Z-RATIO
MA/COM
ETC 1-1-13
–INB
–INA
–OUT
–OUTFILTERED
LT1993-10
+INB
+INA
+OUTFILTERED
+OUT
VOCM
ENABLE
2.2V
82nH 52.3pF
AIN–
LTC2255
ADC
AIN+
20dB Gain
LTC2255 125Msps
14-BIT ADC SAMPLING
AT 92.16Msps
199310 TA01
4-Tone WCDMA Waveform,
LT1993-10 Driving LTC2255
14-Bit ADC at 92.16Msps
0
–10
32768 POINT FFT
TONE CENTER FREQUENCIES
–20 AT 62.5MHz, 67.5MHz,
–30 72.5MHz, 77.5MHz
–40
–50
–60
–70
–80
–90
–100
–110
–120
0
5 10 15 20 25 30 35 40 45
FREQUENCY (MHz)
199310 • TA02
199310fb
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LT1993-10www.DataSheet4U.com
AC ELECTRICAL CHARACTERISTICS TA = 25°C, VCCA = VCCB = VCCC = 5V, VEEA = VEEB = VEEC = 0V,
ENABLE = 0.8V, +INA shorted to +INB (+IN), –INA shorted to –INB (–IN), VOCM = 2.2V, Input common mode voltage = 2.2V, no RLOAD
unless otherwise noted.
SYMBOL
PARAMETER
CONDITIONS
MIN TYP MAX UNITS
Third-Order IMD
3.2VP-P Differential (+OUT, –OUT), RL = 100Ω
2VP-P Differential Composite (+OUTFILTERED,
–OUTFILTERED), f1 = 49.5MHz, f2 = 50.5MHz
–63 dBc
–82 dBc
2VP-P Differential Composite (+OUT, –OUT),
RL = 100Ω, f1 = 49.5MHz, f2 = 50.5MHz
3.2VP-P Differential Composite (+OUTFILTERED,
–OUTFILTERED), f1 = 49.5MHz, f2 = 50.5MHz
–81 dBc
–72 dBc
OIP350M
Output Third-Order Intercept
Differential (+OUTFILTERED, –OUTFILTERED),
f1 = 49.5MHz, f2 = 50.5MHz
44 dBm
NF Noise Figure
Measured Using DC800A Demo Board
12.3 dB
en50M
Input Referred Noise Voltage Density
1dB Compression Point
1.8 nV/√Hz
19.7 dBm
70MHz Signal
Second/Third Harmonic Distortion
Third-Order IMD
2VP-P Differential (+OUTFILTERED, –OUTFILTERED)
2VP-P Differential (+OUT, –OUT)
2VP-P Differential (+OUT, –OUT), RL = 100Ω
2VP-P Differential Composite (+OUTFILTERED,
–OUTFILTERED), f1 = 69.5MHz, f2 = 70.5MHz
–70
–67
–66
–74
dBc
dBc
dBc
dBc
OIP370M
Output Third-Order Intercept
2VP-P Differential Composite (+OUT, –OUT),
RL = 100Ω, f1 = 69.5MHz, f2 = 70.5MHz
Differential (+OUTFILTERED, –OUTFILTERED),
f1 = 69.5MHz, f2 = 70.5MHz
–71 dBc
40 dBm
NF Noise Figure
Measured Using DC800A Demo Board
12.7 dB
en70M
Input Referred Noise Voltage Density
1dB Compression Point
1.9 nV/√Hz
18.5 dBm
100MHz Signal
Second/Third Harmonic Distortion
Third-Order IMD
2VP-P Differential (+OUTFILTERED, –OUTFILTERED)
2VP-P Differential (+OUT, –OUT)
2VP-P Differential (+OUT, –OUT), RL = 100Ω
2VP-P Differential Composite (+OUTFILTERED,
–OUTFILTERED), f1 = 99.5MHz, f2 = 100.5MHz
–60
–55
–52
–61
dBc
dBc
dBc
dBc
OIP3100M
Output Third-Order Intercept
2VP-P Differential Composite (+OUT, –OUT),
RL = 100Ω, f1 = 99.5MHz, f2 = 100.5MHz
Differential (+OUTFILTERED, –OUTFILTERED),
f1 = 99.5MHz, f2 = 100.5MHz
–60 dBc
33.5 dBm
NF Noise Figure
Measured Using DC800A Demo Board
13.2 dB
en100M
Input Referred Noise Voltage Density
1dB Compression Point
2.0 nV/√Hz
17.8 dBm
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: As long as output current and junction temperature are kept below
the Absolute Maximum Ratings, no damage to the part will occur.
Note 3: The LT1993C-10 is guaranteed functional over the operating
temperature range of –40°C to 85°C.
Note 4: The LT1993C-10 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 and 85°C but is not tested or QA
sampled at these temperatures. The LT1993I-10 is guaranteed to meet
specified performance from –40°C to 85°C.
Note 5: This parameter is pulse tested.
Note 6: This parameter is guaranteed to meet specified performance
through design and characterization. It has not been tested.
199310fb
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LT1993-10www.DataSheet4U.com
APPLICATIO S I FOR ATIO
Circuit Description
The LT1993-10 is a low noise, low distortion differential
amplifier/ADC driver with:
• DC to 700MHz –3dB bandwidth
• Fixed gain of 10V/V (20dB) independent of RLOAD
• 100Ω differential input impedance
• Low output impedance
• Built-in, user adjustable output filtering
• Requires minimal support circuitry
Referring to the block diagram, the LT1993-10 uses a
closed-loop topology which incorporates 3 internal am-
plifiers. Two of the amplifiers (A and B) are identical and
drive the differential outputs. The third amplifier (C) is
used to set the output common mode voltage. Gain and
input impedance are set by the 100Ω/500Ω resistors in
the internal feedback network. Output impedance is low,
determined by the inherent output impedance of amplifiers
A and B, and further reduced by internal feedback.
The LT1993-10 also includes built-in single-pole output
filtering. The user has the choice of using the unfiltered
outputs, the filtered outputs (175MHz –3dB lowpass), or
modifying the filtered outputs to alter frequency response
by adding additional components. Many lowpass and
bandpass filters are easily implemented with just one or
two additional components.
The LT1993-10 has been designed to minimize the need
for external support components such as transformers or
AC-coupling capacitors. As an ADC driver, the LT1993-10
requires no external components except for power-supply
bypass capacitors. This allows DC-coupled operation for
applications that have frequency ranges including DC. At
the outputs, the common mode voltage is set via the VOCM
pin, allowing the LT1993-10 to drive ADCs directly. No
output AC-coupling capacitors or transformers are needed.
At the inputs, signals can be differential or single-ended
with virtually no difference in performance. Furthermore,
DC levels at the inputs can be set independently of the
output common mode voltage. These input characteristics
often eliminate the need for an input transformer and/or
AC-coupling capacitors.
Input Impedance and Matching Networks
Because of the internal feedback network, calculation of
the LT1993-10’s input impedance is not straightforward
from examination of the block diagram. Furthermore, the
input impedance when driven differentially is different than
when driven single-ended. When driven differentially, the
LT1993-10’s input impedance is 100Ω (differential); when
driven single-ended, the input impedance is 85.9Ω.
For single-ended 50Ω applications, a 121Ω shunt match-
ing resistor to ground will result in the proper input
termination (Figure 1). For differential inputs there are
several termination options. If the input source is 50Ω
differential, then input matching can be accomplished by
either a 100Ω shunt resistor across the inputs (Figure 3),
or a 49.9Ω shunt resistor on each of the inputs to ground
(Figure 2).
0.1mF
IF IN
121W
ZIN = 50W
SINGLE-ENDED
13 –INB
14 –INA
–OUT 8
LT1993-10
15 +INB
16 +INA
+OUT
5
199310 F01
Figure 1. Input Termination for Single-Ended 50Ω
Input Impedance
IF IN–
ZIN = 509
DIFFERENTIAL
IF IN+
49.99
49.99
13 –INB
14 –INA
–OUT 8
LT1993-10
15 +INB
16 +INA
+OUT
5
199310 F02
Figure 2. Input Termination for Differential 50Ω Input Impedance
IF IN–
ZIN = 509
DIFFERENTIAL
IF IN+
13 –INB
14 –INA
–OUT 8
1009
LT1993-10
15 +INB
16 +INA
+OUT
5
199310 F03
Figure 3. Alternate Input Termination for Differential
50Ω Input Impedance
199310fb
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11 Page | ||
| Páginas | Total 16 Páginas | |
| PDF Descargar | [ Datasheet LT1993-10.PDF ] | |
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