LT1993-4 900MHz Distortion, Noise Differential Amplifier/ Driver 4V/V)
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LT1993-4 900MHz Distortion, Noise Differential Amplifier/ Driver 4V/V) DESCRIPTIO
LT®1993-4 distortion, noise Differential Amplifier/ADC driver applications from 900MHz. LT1993-4 been designed ease use, with minimal support circuitry required. Exceptionally input-referred noise distortion products (with either single-ended differential inputs) make LT1993-4 excellent solution driving high speed 12bit 14-bit ADCs. addition normal unfiltered outputs (+OUT -OUT), LT1993-4 built-in 175MHz differential lowpass filter additional pair filtered outputs (+OUTFILTERED, -OUTFILTERED) reduce external filtering components when driving high speed ADCs. output common mode voltage easily VOCM pin, eliminating either output transformer AC-coupling capacitors many applications. LT1993-4 designed meet demanding requirements communications transceiver applications. used differential driver, general-purpose differential gain block, other application requiring differential drive. LT1993-4 used data acquisition systems required function frequencies down LT1993-4 operates supply consumes 100mA. comes compact 16-lead package operates over -40°C 85°C temperature range.
4-Tone WCDMA Waveform, LT1993-4 Driving LTC2255 14-Bit 92.16Msps
32768 POINT TONE CENTER FREQUENCIES 62.5MHz, 67.5MHz, 72.5MHz, 77.5MHz
900MHz -3dB Bandwidth Fixed Gain 4V/V (12dB) Distortion: 40dBm OIP3, -73dBc (70MHz 2VP-P) 51dBm OIP3, -94dBc (10MHz 2VP-P) Noise: 14.5dB 2.35nV/Hz (70MHz) Differential Inputs Outputs Additional Filtered Outputs Adjustable Output Common Mode Voltage AC-Coupled Operation Minimal Support Circuitry Required Small 0.75mm Tall 16-Lead Package
APPLICATIO
Differential Driver for: Imaging Communications Differential Driver/Receiver Single Ended Differential Conversion Differential Single Ended Conversion Level Shifting Sampling Receivers Filter Interfacing/Buffering
registered trademarks Linear Technology Corporation. other trademarks property their respective owners.
TYPICAL APPLICATIO
Z-RATIO
Driver with Single-Ended Differential Conversion
0.1µF -OUT 82nH AMPLITUDE (dBFS) -INB -INA 12.2 AIN- 52.3pF LTC2255 AIN+ 12.2 LTC2255 125Msps 14-BIT SAMPLING 92.16Msps
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-100 -110 -120
70MHz
MA/COM ETC1-1-13
0.1µF
-OUTFILTERED LT1993-4 +OUTFILTERED +INB +OUT +INA VOCM ENABLE 2.2V
12dB GAIN
FREQUENCY (MHz)
LT19934 TA02
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LT1993-4 ABSOLUTE
(Note
RATI
PACKAGE/ORDER ATIO
VIEW +INA +INB -INA -INB VCCC VOCM VCCA VEEA +OUT +OUTFILTERED -OUTFILTERED -OUT VEEC ENABLE VCCB VEEB
Total Supply Voltage (VCCA/VCCB/VCCC VEEA/VEEB/VEEC) .5.5V Input Current (+INA, -INA, +INB, -INB, VOCM, ENABLE).±10mA Output Current (Continuous) (Note +OUT, -OUT (DC) .±100mA (AC) .±100mA +OUTFILTERED, -OUTFILTERED (DC) .±15mA (AC) .±45mA Output Short Circuit Duration (Note Indefinite Operating Temperature Range (Note -40°C 85°C Specified Temperature Range (Note -40°C 85°C Storage Temperature Range. -65°C 125°C Junction Temperature 125°C Lead Temperature Range (Soldering sec) 300°C
PACKAGE 16-LEAD (3mm 3mm) PLASTIC TJMAX 125°C, 68°C/W, 4.2°C/W EXPOSED (PIN MUST SOLDERED
ORDER PART NUMBER LT1993CUD-4 LT1993IUD-4
PART MARKING* LBNS LBNS
Order Options Tape Reel: Lead Free: #PBF Lead Free Tape Reel: #TRPBF Lead Free Part Marking: http://www.linear.com/leadfree/ Consult Marketing parts specified with wider operating temperature ranges. *The temperature grade identified label shipping container.
ELECTRICAL CHARACTERISTICS
SYMBOL GDIFF VSWINGMIN VSWINGMAX VSWINGDIFF IOUT TCVOS IVRMIN IVRMAX RINDIFF CINDIFF Output Voltage Swing Output Current Drive Input Offset Voltage PARAMETER Gain CONDITIONS
denotes specifications which apply over full operating temperature range, otherwise specifications 25°C. VCCA VCCB VCCC VEEA VEEB VEEC ENABLE 0.8V, +INA shorted +INB (+IN), -INA shorted -INB (-IN), VOCM 2.2V, Input common mode voltage 2.2V, RLOAD unless otherwise noted.
11.9 0.25
12.4 0.35
UNITS VP-P VP-P
Input/Output Characteristics (+INA, +INB, -INA, -INB, +OUT, -OUT, +OUTFILTERED, -OUTFILTERED) Differential (+OUT, -OUT), ±0.4V Differential Single-Ended +OUT, -OUT, +OUTFILTERED, -OUTFILTERED. ±1.2V Differential Single-Ended +OUT, -OUT, +OUTFILTERED, -OUTFILTERED. ±1.2V Differential Differential (+OUT, -OUT), ±1.2VP-P Differential (Note 11.6
-6.5
3.75
Input Offset Voltage Drift Input Voltage Range, Input Voltage Range, Differential Input Resistance Differential Input Capacitance
TMIN TMAX Single-Ended Single-Ended
µV/°C
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LT1993-4 ELECTRICAL CHARACTERISTICS
SYMBOL CMRR ROUTDIFF COUTDIFF VOCMMIN VOCMMAX VOSCM IBIASCM RINCM CINCM ENABLE Power Supply ISDISABLED PSRR Operating Range Supply Current Supply Current (Disabled) Power Supply Rejection Ratio ENABLE 0.8V ENABLE 5.5V
denotes specifications which apply over full operating temperature range, otherwise specifications 25°C. VCCA VCCB VCCC VEEA VEEB VEEC ENABLE 0.8V, +INA shorted +INB (+IN), -INA shorted -INB (-IN), VOCM 2.2V, Input common mode voltage 2.2V, RLOAD unless otherwise noted.
PARAMETER Common Mode Rejection Ratio Output Resistance Output Capacitance Common Mode Gain Output Common Mode Voltage Adjustment Range, Output Common Mode Voltage Adjustment Range, Output Common Mode Offset Voltage VOCM Input Bias Current VOCM Input Resistance VOCM Input Capacitance ENABLE Input Voltage ENABLE Input High Voltage ENABLE Input Current ENABLE Input High Current ENABLE 0.8V ENABLE
CONDITIONS Input Common Mode 0.5V 4.3V
UNITS
Common Mode Voltage Control (VOCM Pin) Differential (+OUT, -OUT), VOCM 1.2V 3.6V Differential (+OUT, -OUT), VOCM 1.4V 3.4V Measured Single-Ended +OUT -OUT
Measured Single-Ended +OUT -OUT
Measured from VOCM Average +OUT -OUT
ELECTRICAL CHARACTERISTICS
SYMBOL -3dBBW 0.1dBBW 0.5dBBW ts1% tOFF PARAMETER -3dB Bandwidth Bandwidth 0.1dB Flatness Bandwidth 0.5dB Flatness Slew Rate Settling Time Turn-On Time Turn-Off Time Input/Output Characteristics
25°C, VCCA VCCB VCCC VEEA VEEB VEEC ENABLE 0.8V, +INA shorted +INB (+IN), -INA shorted -INB (-IN), VOCM 2.2V, Input common mode voltage 2.2V, RLOAD unless otherwise noted.
CONDITIONS 200mVP-P Differential (+OUT, -OUT) 200mVP-P Differential (+OUT, -OUT) 200mVP-P Differential (+OUT, -OUT) 3.2VP-P Differential (+OUT, -OUT) Settling 1VP-P Differential Step (+OUT, -OUT) 1100 UNITS V/µs
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LT1993-4 ELECTRICAL CHARACTERISTICS
SYMBOL -3dBBWCM SRCM 1kHz Signal Second/Third Harmonic Distortion 2VP-P Differential (+OUTFILTERED, -OUTFILTERED) 2VP-P Differential (+OUT, -OUT) 2VP-P Differential (+OUT, -OUT), 3.2VP-P Differential (+OUTFILTERED, -OUTFILTERED) 3.2VP-P Differential (+OUT, -OUT) 3.2VP-P Differential (+OUT, -OUT), Third-Order 2VP-P Differential Composite (+OUTFILTERED, -OUTFILTERED), 0.95kHz, 1.05kHz 2VP-P Differential Composite (+OUT, -OUT), 100, 0.95kHz, 1.05kHz 3.2VP-P Differential Composite (+OUTFILTERED, -OUTFILTERED), 0.95kHz, 1.05kHz Differential (+OUTFILTERED, -OUTFILTERED), 0.95kHz, 1.05kHz -100 -100 -100 -102 -102 2.15 22.7 2VP-P Differential (+OUTFILTERED, -OUTFILTERED) 2VP-P Differential (+OUT, -OUT) 2VP-P Differential (+OUT, -OUT), 3.2VP-P Differential (+OUTFILTERED, -OUTFILTERED) 3.2VP-P Differential (+OUT, -OUT) 3.2VP-P Differential (+OUT, -OUT), Third-Order 2VP-P Differential Composite (+OUTFILTERED, -OUTFILTERED), 9.5MHz, 10.5MHz 2VP-P Differential Composite (+OUT, -OUT), 100, 9.5MHz, 10.5MHz 3.2VP-P Differential Composite (+OUTFILTERED, -OUTFILTERED), 9.5MHz, 10.5MHz Differential (+OUTFILTERED, -OUTFILTERED), 9.5MHz, 10.5MHz Measured Using DC800A Demo Board 13.7 2.15 22.6 2VP-P Differential (+OUTFILTERED, -OUTFILTERED) 2VP-P Differential (+OUT, -OUT) 2VP-P Differential (+OUT, -OUT), nV/Hz nV/Hz
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25°C, VCCA VCCB VCCC VEEA VEEB VEEC ENABLE 0.8V, +INA shorted +INB (+IN), -INA shorted -INB (-IN), VOCM 2.2V, Input common mode voltage 2.2V, RLOAD unless otherwise noted.
PARAMETER Common Mode Small-Signal -3dB Bandwidth Common Mode Slew Rate CONDITIONS 0.1VP-P VOCM, Measured Single-Ended +OUT -OUT 1.2V 3.6V Step VOCM UNITS V/µs Common Mode Voltage Control (VOCM Pin)
Noise/Harmonic Performance Input/output Characteristics
OIP31k en1k 10MHz Signal
Output Third-Order Intercept Input Referred Noise Voltage Density Compression Point Second/Third Harmonic Distortion
OIP310M en10M 50MHz Signal
Output Third-Order Intercept Noise Figure Input Referred Noise Voltage Density Compression Point Second/Third Harmonic Distortion
LT1993-4 ELECTRICAL CHARACTERISTICS
SYMBOL PARAMETER
25°C, VCCA VCCB VCCC VEEA VEEB VEEC ENABLE 0.8V, +INA shorted +INB (+IN), -INA shorted -INB (-IN), VOCM 2.2V, Input common mode voltage 2.2V, RLOAD unless otherwise noted.
CONDITIONS 3.2VP-P Differential (+OUTFILTERED, -OUTFILTERED) 3.2VP-P Differential (+OUT, -OUT) 3.2VP-P Differential (+OUT, -OUT), Third-Order 2VP-P Differential Composite (+OUTFILTERED, -OUTFILTERED), 49.5MHz, 50.5MHz 2VP-P Differential Composite (+OUT, -OUT), 100, 49.5MHz, 50.5MHz 3.2VP-P Differential Composite (+OUTFILTERED, -OUTFILTERED), 49.5MHz, 50.5MHz Differential (+OUTFILTERED, -OUTFILTERED), 49.5MHz, 50.5MHz Measured Using DC800A Demo Board 14.1 2.25 19.7 2VP-P Differential (+OUTFILTERED, -OUTFILTERED) 2VP-P Differential (+OUT, -OUT) 2VP-P Differential (+OUT, -OUT), Third-Order 2VP-P Differential Composite (+OUTFILTERED, -OUTFILTERED), 69.5MHz, 70.5MHz 2VP-P Differential Composite (+OUT, -OUT), 100, 69.5MHz, 70.5MHz Differential (+OUTFILTERED, -OUTFILTERED), 69.5MHz, 70.5MHz Measured Using DC800A Demo Board 14.5 2.35 18.5 2VP-P Differential (+OUTFILTERED, -OUTFILTERED) 2VP-P Differential (+OUT, -OUT) 2VP-P Differential (+OUT, -OUT), Third-Order 2VP-P Differential Composite (+OUTFILTERED, -OUTFILTERED), 99.5MHz, 100.5MHz 2VP-P Differential Composite (+OUT, -OUT), 100, 99.5MHz, 100.5MHz Differential (+OUTFILTERED, -OUTFILTERED), 99.5MHz, 100.5MHz Measured Using DC800A Demo Board 33.5 15.1 2.55 17.8 UNITS nV/Hz nV/Hz nV/Hz
OIP350M en50M 70MHz Signal
Output Third-Order Intercept Noise Figure Input Referred Noise Voltage Density Compression Point Second/Third Harmonic Distortion
OIP370M en70M 100MHz Signal
Output Third-Order Intercept Noise Figure Input Referred Noise Voltage Density Compression Point Second/Third Harmonic Distortion
OIP3100M en100M
Output Third-Order Intercept Noise Figure Input Referred Noise Voltage Density Compression Point
Note Absolute Maximum Ratings those values beyond which life device impaired. Note long output current junction temperature kept below Absolute Maximum Ratings, damage part will occur. Note LT1993C-4 guaranteed functional over operating temperature range -40°C 85°C.
Note LT1993C-4 guaranteed meet specified performance from 70°C. designed, characterized expected meet specified performance from -40°C 85°C tested sampled these temperatures. LT1993I-4 guaranteed meet specified performance from -40°C 85°C. Note This parameter pulse tested. Note This parameter guaranteed meet specified performance through design characterization. been tested.
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LT1993-4 TYPICAL PERFOR CHARACTERISTICS
Frequency Response RLOAD
GAIN (dB) GAIN (dB) 50mVP-P UNFILTERED: RLOAD FILTERED: RLOAD (EXTERNAL) (INTERNAL FILTERED OUTPUTS) 1000 FREQUENCY (MHz) FILTERED OUTPUTS UNFILTERED OUTPUTS 1.8pF 10000
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GAIN (dB)
Third Order Intermodulation Distortion Frequency Differential Input, RLOAD
THIRD ORDER (dBc) -100 -110 FREQUENCY (MHz) UNFILTERED OUTPUTS FILTERED OUTPUTS TONES, 2VP-P COMPOSITE 1MHz TONE SPACING THIRD ORDER (dBc)
THIRD ORDER (dBc)
Output Third Order Intercept Frequency, Differential Input RLOAD
OUTPUT (dBm) OUTPUT (dBm) FREQUENCY (MHz) FILTERED OUTPUTS UNFILTERED OUTPUTS TONES, 2VP-P COMPOSITE 1MHz TONE SPACING
OUTPUT (dBm)
Frequency Response CLOAD RLOAD
50mVP-P UNFILTERED OUTPUTS 10pF
Frequency Response RLOAD
UNFILTERED OUTPUTS
FILTERED OUTPUTS
1000 FREQUENCY (MHz)
10000
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50mVP-P UNFILTERED: RLOAD FILTERED: RLOAD (EXTERNAL) (INTERNAL FILTERED OUTPUTS) 1000 FREQUENCY (MHz)
10000
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Third Order Intermodulation Distortion Frequency Differential Input, RLOAD
TONES, 2VP-P COMPOSITE 1MHz TONE SPACING FILTERED OUTPUTS -100 -110 FREQUENCY (MHz)
Third Order Intermodulation Distortion Frequency Differential Input, RLOAD
TONES, 2VP-P COMPOSITE 1MHz TONE SPACING FILTERED OUTPUTS
UNFILTERED OUTPUTS
UNFILTERED OUTPUTS
-100 -110
FREQUENCY (MHz)
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Output Third Order Intercept Frequency, Differential Input RLOAD
TONES, 2VP-P COMPOSITE 1MHz TONE SPACING UNFILTERED OUTPUTS FILTERED OUTPUTS FREQUENCY (MHz)
Output Third Order Intercept Frequency, Differential Input RLOAD
TONES, 2VP-P COMPOSITE 1MHz TONE SPACING
UNFILTERED OUTPUTS
FILTERED OUTPUTS
FREQUENCY (MHz)
19334
19334
19334
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LT1993-4 TYPICAL PERFOR CHARACTERISTICS
Distortion (Filtered) Frequency Differential Input, RLOAD
FILTERED OUTPUTS VOUT 2VP-P DISTORTION (dBc) DISTORTION (dBc) -100 -110 FREQUENCY (MHz) 1000
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-100 -110 FREQUENCY (MHz)
DISTORTION (dBc)
Output Compression Frequency
OUTPUT COMPRESSION (dBm) FREQUENCY (MHz) 1000
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RLOAD RLOAD NOISE FIGURE (dB)
INPUT REFERRED NOISE VOLTAGE (nV/Hz)
UNFILTERED OUTPUTS
Reverse Isolation Frequency
INPUT IMPEDANCE (MAGNITUDE PHASE°) ISOLATION (dB) -100 -110 1000 FREQUENCY (MHz) 10000
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UNFILTERED OUTPUTS
IMPEDANCE MAGNITUDE
IMPEDANCE PHASE
OUTPUT IMPEDANCE
Distortion (Unfiltered) Frequency, Differential Input, RLOAD
UNFILTERED OUTPUTS VOUT 2VP-P 1000
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Distortion Output Amplitude 70MHz Differential Input RLOAD
UNFILTERED OUTPUTS FILTERED OUTPUTS UNFILTERED OUTPUTS FILTERED OUTPUTS OUTPUT AMPLITUDE (dBm)
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-100
Noise Figure Frequency
MEASURED USING DC800A DEMO BOARD FREQUENCY (MHz) 1000
''!"
Input Referred Noise Voltage Frequency
FREQUENCY (MHz)
1000
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Differential Input Impedance Frequency
Differential Output Impedance Frequency
UNFILTERED OUTPUTS
-100 FREQUENCY (MHz) 1000
''!"
FREQUENCY (MHz) 1000
''!"
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LT1993-4 TYPICAL PERFOR CHARACTERISTICS
Input Reflection Coefficient Frequency
INPUT REFLECTION COEFFICIENT (S11) FREQUENCY (MHz) 1000
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OUTPUT REFLECTION COEFFICIENT (S22)
MEASURED USING DC800A DEMO BOARD
PSRR, CMRR (dB)
Small-Signal Transient Response
2.28 2.26 OUTPUT VOLTAGE OUTPUT VOLTAGE 2.24 2.22 2.20 2.18 2.16 2.14 2.12 TIME (ns)
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RLOAD OUTPUT
OUTPUT VOLTAGE
Distortion Output Common Mode Voltage, LT1993-4 Driving LTC2249 14-Bit
DISTORTION (dBc) OUTPUT COMMON MODE VOLTAGE
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FILTERED OUTPUTS, RLOAD VOUT 70MHz 2VP-P
VOLTAGE
VOLTAGE
Output Reflection Coefficient Frequency
FREQUENCY (MHz) 1000
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PSRR, CMRR Frequency
FREQUENCY (MHz) 1000
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MEASURED USING DC800A DEMO BOARD
UNFILTERED OUTPUTS
CMRR
PSRR
Large-Signal Transient Response
TIME (ns)
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Overdrive Recovery Time
TIME (ns)
''!"
RLOAD OUTPUT
+OUT
RLOAD OUTPUT
-OUT
Turn-On Time
+OUT -OUT RLOAD OUTPUT ENABLE TIME (ns)
''!"
Turn-Off Time
+OUT -OUT
ENABLE
RLOAD OUTPUT TIME (ns)
''!"
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LT1993-4 TYPICAL PERFOR CHARACTERISTICS
30MHz 8192 Point FFT, LT1993-4 Driving LTC2249 14-Bit
AMPLITUDE (dBFS) AMPLITUDE (dBFS) -100 -110 -120 FREQUENCY (MHz) 8192 POINT 30MHz, -1dBFS FILTERED OUTPUTS AMPLITUDE (dBFS) -100 -110 -120 FREQUENCY (MHz) 8192 POINT 50MHz, -1dBFS FILTERED OUTPUTS
70MHz 2-Tone 32768 Point LT1993-4 Driving LTC2249 14-Bit
AMPLITUDE (dBFS) -100 -110 -120 FREQUENCY (MHz) 32768 POINT TONE 69.5MHz, -7dBFS TONE 70.5MHz, -7dBFS FILTERED OUTPUTS AMPLITUDE (dBFS) -100 -110 -120
AMPLITUDE (dBFS)
CTIO
VOCM (Pin This sets output common mode voltage. Without additional biasing, both inputs bias this voltage well. This input high impedance. VCCA, VCCB, VCCC (Pins Positive Power Supply (Normally Tied 5V). three pins must tied same voltage. Bypass each with 1000pF 0.1µF capacitors close package possible. Split supplies possible long voltage between VEEA, VEEB, VEEC (Pins 12): Negative Power Supply (Normally Tied Ground). three pins must tied same voltage. Split supplies possible long voltage between these pins tied ground, bypass each with 1000pF 0.1µF capacitors close package possible. +OUT, -OUT (Pins Outputs (Unfiltered). These pins high bandwidth, low-impedance outputs. output voltage these pins voltage applied VOCM.
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50MHz 8192 Point FFT, LT1993-4 Driving LTC2249 14-Bit
-100 -110 -120
70MHz 8192 Point FFT, LT1993-4 Driving LTC2249 14-Bit
8192 POINT 70MHz, -1dBFS FILTERED OUTPUTS
FREQUENCY (MHz)
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2-Tone WCDMA Waveform LT1993-4 Driving LTC2255 14-Bit 92.16Msps
32768 POINT TONE CENTER FREQUENCIES 67.5MHz, 72.5MHz -100 -110 FREQUENCY (MHz) -120
4-Tone WCDMA Waveform LT1993-4 Driving LTC2255 14-Bit 92.16Msps
32768 POINT TONE CENTER FREQUENCIES 62.5MHz, 67.5MHz, 72.5MHz, 77.5MHz
FREQUENCY (MHz)
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LT1993-4 CTIO
+OUTFILTERED, -OUTFILTERED (Pins Filtered Outputs. These pins series resistor from unfiltered outputs three 12pF capacitors. Each output 12pF VEE, plus additional 12pF between each (See Block Diagram). This filter -3dB bandwidth 175MHz. ENABLE (Pin 11): This logic input referenced VEEC pin. low, LT1993-4 enabled draws typically 100mA supply current. high, LT1993-4 disabled draws typically 250µA. -INA, -INB (Pins 13): Negative Inputs. These pins normally tied together. These inputs ACcoupled. inputs AC-coupled, they will self-bias voltage applied VOCM pin. +INA, +INB (Pins 15): Positive Inputs. These pins normally tied together. These inputs ACcoupled. inputs AC-coupled, they will self-bias voltage applied VOCM pin. Exposed (Pin 17): VEEC (Pin 12). split supplies used, ground.
BLOCK DIAGRA
-INA -INB
+INA +INB
VCCA
VEEA 12pF +OUT +OUTFILTERED VCCC VOCM
VEEA
12pF
VCCB VEEC -OUTFILTERED -OUT 12pF VEEB
VEEB
BIAS
VCCA
VCCB
VCCC
ENABLE
VEEA
VEEB
VEEC
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LT1993-4 APPLICATIO ATIO
Circuit Description LT1993-4 noise, distortion differential amplifier/ADC driver with: 900MHz -3dB bandwidth Fixed gain 4V/V (12dB) independent RLOAD differential input impedance output impedance Built-in, user adjustable output filtering Requires minimal support circuitry Referring block diagram, LT1993-4 uses closedloop topology which incorporates internal amplifiers. amplifiers identical drive differential outputs. third amplifier used output common mode voltage. Gain input impedance 100/200 resistors internal feedback network. Output impedance low, determined inherent output impedance amplifiers further reduced internal feedback. LT1993-4 also includes built-in single-pole output filtering. user choice using unfiltered outputs, filtered outputs (175MHz -3dB lowpass), modifying filtered outputs alter frequency response adding additional components. Many lowpass bandpass filters easily implemented with just additional components. LT1993-4 been designed minimize need external support components such transformers AC-coupling capacitors. driver, LT1993-4 requires external components except power-supply bypass capacitors. This allows DC-coupled operation applications that have frequency ranges including outputs, common mode voltage VOCM pin, allowing LT1993-4 drive ADCs directly. output AC-coupling capacitors transformers needed. inputs, signals differential single-ended with virtually difference performance. Furthermore, levels inputs independently output common mode voltage. These input characteristics often eliminate need input transformer and/or AC-coupling capacitors.
Input Impedance Matching Networks Because internal feedback network, calculation LT1993-4's input impedance straightforward from examination block diagram. Furthermore, input impedance when driven differentially different than when driven single-ended. When driven differentially, LT1993-4's input impedance (differential); when driven single-ended, input impedance single-ended applications, shunt matching resistor ground will result proper input termination (Figure differential inputs there several termination options. input source differential, then input matching accomplished either shunt resistor across inputs (Figure 49.9 shunt resistor each inputs ground (Figure
-INB -INA -OUT LT1993-4 +INB +INA +OUT
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Figure Input Termination Single-Ended Input Impedance
-INB -INA -OUT LT1993-4
+INB +INA
+OUT
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Figure Input Termination Differential Input Impedance
-INB -INA -OUT LT1993-4
+INB +INA
+OUT
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Figure Alternate Input Termination Differential Input Impedance
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LT1993-4 APPLICATIO ATIO
Single-Ended Differential Operation LT1993-4's performance with single-ended inputs comparable performance with differential inputs. This excellent single-ended performance largely internal topology LT1993-4. Referring block diagram, +INA +INB pins driven with single-ended signal (while -INA -INB tied ground), then +OUT -OUT pins driven differentially without voltage swing needed from amplifier Single-ended differential conversion using more conventional topologies suffers from performance limitations common mode amplifier. Driving ADCs LT1993-4 been specifically designed interface directly with high speed Analog Digital Converters (ADCs). general, these ADCs have differential inputs, with input impedance higher. addition, there generally some form lowpass bandpass filtering just prior limit input noise ADC, thereby improving system signal noise ratio. Both unfiltered filtered outputs LT1993-4 easily drive high impedance inputs these differential ADCs. filtered outputs used, then cutoff frequency type filter tailored specific application needed. Wideband Applications (Using +OUT -OUT Pins) applications where full bandwidth LT1993-4 desired, unfiltered output pins (+OUT -OUT) should used. They have output impedance; therefore, gain unaffected output load. Capacitance excess placed directly unfiltered outputs results additional peaking reduced performance. When driving directly, small series resistance recommended between LT1993-4's outputs inputs (Figure This resistance helps eliminate resonances associated with bond wire inductances either inputs LT1993-4's outputs. value between gives excellent results.
-OUT LT1993-4 +OUT
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Figure Adding Small Series LT1993-4 Output
Filtered Applications (Using +OUTFILTERED -OUTFILTERED Pins) Filtering output LT1993-4 often desired provide either anti-aliasing improved signal noise ratio. simplify this filtering, LT1993-4 includes additional pair differential outputs (+OUTFILTERED -OUTFILTERED) which incorporate internal lowpass filter network with -3dB bandwidth 175MHz (Figure These pins each have output impedance Internal capacitances 12pF each filtered output, plus additional 12pF capacitor connected differentially between filtered outputs. This resistor/capacitor combination creates filtered outputs that look like series resistor with 36pF capacitor shunting each filtered output ground, giving -3dB bandwidth 175MHz.
LT1993-4 12pF +OUT
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-OUT
12pF -OUTFILTERED 12pF +OUTFILTERED FILTERED OUTPUT (175MHz)
Figure LT1993-4 Internal Filter Topology -3dB 175MHz
filter cutoff frequency easily modified with just external components. increase cutoff frequency, simply equal value resistors, between +OUT +OUTFILTERED other between -OUT -OUTFILTERED (Figure These resistors parallel with internal resistor, lowering overall resistance increasing filter bandwidth. double filter bandwidth, example, external resistors lower series resistance 12.5. 36pF capacitance remains unchanged, filter bandwidth doubles.
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LT1993-4 APPLICATIO ATIO
LT1993-4 12pF -OUTFILTERED 12pF +OUTFILTERED 12pF +OUT
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-OUT
FILTERED OUTPUT (350MHz) 12pF
Figure LT1993-4 Internal Filter Topology Modified Filter Bandwidth External Resistors)
decrease filter bandwidth, external capacitors, from +OUTFILTERED ground, other from -OUTFILTERED ground. single differential capacitor connected between +OUTFILTERED -OUTFILTERED also used, since being driven differentially will appear each filtered output single-ended capacitance twice value. halve filter bandwidth, example, 36pF capacitors could added (one from each filtered output ground). Alternatively 18pF capacitor could added between filtered outputs, again halving filter bandwidth. Combinations capacitors could used well; three capacitor solution 12pF from each filtered output ground plus 12pF capacitor between filtered outputs would also halve filter bandwidth (Figure
LT1993-4 12pF -OUTFILTERED 12pF 12pF +OUT
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-OUT
12pF FILTERED OUTPUT (87.5MHz)
12pF +OUTFILTERED
12pF
Figure LT1993-4 Internal Filter Topology Modified 1/2x Filter Bandwidth External Capacitors)
Bandpass filtering also easily implemented with just external components. additional 120pF 39nH, each added differentially between +OUTFILTERED -OUTFILTERED creates bandpass filter with 71MHz center frequency, -3dB points 55MHz 87MHz, 1.6dB insertion loss (Figure
LT1993-4 12pF -OUTFILTERED FILTERED OUTPUT 120pF (71MHz BANDPASS, -3dB 55MHz/87MHz) -OUT 12pF 39nH +OUTFILTERED +OUT
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Figure LT1993-4 Output Filter Topology Modified Bandpass Filtering External Inductor, External Capacitor)
Output Common Mode Adjustment LT1993-4's output common mode voltage VOCM pin. high-impedance input, capable setting output common mode voltage anywhere range from 1.1V 3.6V. Bandwidth VOCM typically 300MHz, applications where VOCM tied bias voltage, 0.1µF capacitor this recommended. best distortion performance, voltage VOCM should between 1.8V 2.6V. When interfacing with most ADCs, there generally VOCM output that about half supply voltage ADC. ADCs such LTC17XX family, this VOCM output should connected directly (with addition 0.1µF capacitor) input VOCM LT1993-4. ADCs such LTC22XX families, LT19934 will function properly using 1.65V from ADC's reference pin, improved Spurious Free Dynamic Range (SFDR) distortion performance achieved level-shifting LTC22XX's reference voltage least 1.8V. This accomplished shown Figure using resistor divider between LTC22XX's output then bypassing LT1993-4's VOCM with 0.1µF capacitor. common mode voltage above 1.9V, coupling capacitors recommended between LT1993-4 LTC22XX because input voltage range constraints ADC.
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LT1993-4 APPLICATIO ATIO
1.9V 4.02k -INB -INA VOCM +OUTFILTERED LT1993-4 -OUTFILTERED +INB +INA
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1.5V AIN+ LTC22xx AIN-
Figure Level Shifting Voltage Improved SFDR
Large Output Voltage Swings LT1993-4 been designed provide 3.2VP-P output swing needed LTC1748 family 14-bit low-noise ADCs. This additional output swing improves system 4dB. Typical performance curves specifications have been included these applications. Input Bias Voltage Bias Current input pins LT1993-4 internally biased voltage applied VOCM pin. external biasing resistors needed, even AC-coupled operation.
PACKAGE DESCRIPTIO
Package 16-Lead Plastic (3mm 3mm)
(Reference 05-08-1691)
BOTTOM VIEW-EXPOSED 3.00 0.10 SIDES) 0.70 ±0.05 MARK (NOTE 1.45 0.10 (4-SIDES) 0.75 0.05 0.115 0.40 0.10 NOTCH 0.20 0.25 CHAMFER
3.50 0.05 1.45 0.05 2.10 0.05 SIDES)
PACKAGE OUTLINE 0.25 ±0.05 0.50 RECOMMENDED SOLDER PITCH DIMENSIONS NOTE: DRAWING CONFORMS JEDEC PACKAGE OUTLINE MO-220 VARIATION (WEED-2) DRAWING SCALE DIMENSIONS MILLIMETERS 0.200 0.00 0.05
input bias current determined voltage difference between input common mode voltage VOCM (which sets output common mode voltage). both positive negative inputs, voltage difference imposed across 100, generating input bias current. example, inputs tied 2.5V with VOCM 2.2V, then total input bias current will flow into LT1993-4's +INA +INB pins. Furthermore, additional input bias current totaling will flow into -INA -INB inputs. Application (Demo) Boards DC800A Demo Board been created stand-alone evaluation LT1993-4 with either single-ended differential input output signals. shown, accepts single-ended input produces single-ended output that LT1993-4 evaluated using standard laboratory test equipment. more information this Demo Board, please refer Demo Board section this datasheet. There also additional demo boards available that combine LT1993-4 with variety different Linear Technology ADCs. Please contact factory more information these demo boards.
(UD16) 0904
0.25 0.05 0.50
DIMENSIONS EXPOSED BOTTOM PACKAGE INCLUDE MOLD FLASH. MOLD FLASH, PRESENT, SHALL EXCEED 0.15mm SIDE EXPOSED SHALL SOLDER PLATED SHADED AREA ONLY REFERENCE LOCATION BOTTOM PACKAGE
19934fa
LT1993-4 TYPICAL APPLICATIO
19934fa
Information furnished Linear Technology Corporation believed accurate reliable. However, responsibility assumed use. Linear Technology Corporation makes representation that interconnection circuits described herein will infringe existing patent rights.
LT1993-4 TYPICAL APPLICATIO
ENABLE 0.1mF Z-RATIO MA/COM ETC1-1-13 +INB VEEC -INB ENABLE -OUT 24.9W 0.1mF Z-RATIO 0.1mF 0.1mF
0.1mF
0.1mF
+OUTFILTERED
+INA VCCC
VOCM
VCCA
+OUT VEEA
24.9W
MINI0dB CIRCUITS 4-19
0.01mF
VOCM
TEST
0.1mF
MINICIRCUITS 4-19
MINICIRCUITS 4-19
4.7mF
NOTES: UNLESS OTHERWISE SPECIFIED, STUFF.
RELATED PARTS
PART NUMBER LT1993-2 LT1993-10 LT5514 LT6600-2.5 LT6600-5 LT6600-10 LT6600-20 DESCRIPTION 800MHz Differential Amplifier/ADC Driver 700MHz Differential Amplifier/ADC Driver Ultralow Distortion Amplifier/ADC Driver Very Noise Differential Amplifier 2.5MHz Lowpass Filter Very Noise Differential Amplifier 5MHz Lowpass Filter Very Noise Differential Amplifier 10MHz Lowpass Filter Very Noise Differential Amplifier 20MHz Lowpass Filter COMMENTS 2V/V, 12.3dB, OIP3 38dBm 70MHz 10V/V, 12.7dB, OIP3 40dBm 70MHz Digitally Controlled Gain Output 47dBm 100MHz 86dB with Supply, SO-8 Package 82dB with Supply, SO-8 Package 82dB with Supply, SO-8 Package 76dB with Supply, SO-8 Package
Linear Technology Corporation
(408) 432-1900 FAX: (408) 434-0507
1630 McCarthy Blvd., Milpitas, 95035-7417
www.linear.com
LINEAR TECHNOLOGY CORPORATION 2005
Demo Circuit DC800A Schematic Test Circuit)
1000pF 0.01mF VCCB VEEB -INA -OUTFILTERED LT1993-4 -OUT +10.8dB +6dB +OUT 1000pF 1000pF 0.01mF 0.01mF 0.1mF 0.1mF 0.1mF TEST
19934 TA03
19934fa LT/LT 1005 PRINTED
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