Datasheet High Speed ADC Products Datasheet (LINEAR TECHNOLOGY)

11.2007

High Speed ADC Products

High Performance Analog ICs

High Speed ADC Products

Introduction

LTC2209 High Performance ADC Family

LTC2207 High Performance ADC Family

LTC2220-1 and LTC2242-12 High IF Sampling ADC Families

LTC2224 High IF Sampling ADC Family

LTC2255 Lowest Power ADC Family

LTC2285 Lowest Power Dual ADC Family

LTC1750 High Performance 5V ADC Family

Fully Differential ADC Drivers

CMOS vs LVDS Outputs

01

02

03

04

05

06

07

08

09

11

25Msps 40Msps 65Msps 80Msps 105Msps

125Msps to

135Msps

160Msps to

185Msps

210Msps and

250Msps10Msps

2203 2204 2205 2206 2207 22082202

2205-14 2206-14 2207-14 2208-14

2209

2209-14

2246 2247 2248 2249 2254 22552245

2291 2292 2293 2294 2282 22832290

2228 2229 2252 22532225

2296 2297 2298 2299 2284 22852295

2223 2222 2224 2240-12

2242-12

2220-1

2241-12

2221

2220

2226 2227

2285 2287 2288 2289 2280 2281

2238 2239 2250 2251

2233 2232 2234

2242-10

2240-10

2241-10

2231

2230

2236 2237

16-Bit

14-Bit

12-Bit

10-Bit

Lowest Power High Speed ADCs

Contents

Lowest Power High Speed ADCs

Introduction

Our high speed ADCs offer the lowest power consumption and highest AC performance in the industry.

They incorporate many unique features to ease system design and space constraints, including integrated

bypass capacitance and integrated series resistance for 50ohm digital outputs. Each ADC family offers the

ability to operate the digital output supply as low as 0.5V, helping to reduce digital feedback and allowing

direct connection to low voltage digital interfaces.

The entire ADC portfolio is supported with evaluation boards and a free Quick Eval-II PScope software tool

that can be downloaded from our website at www.linear.com/company/software.jsp. The following tables

provide a demo board selection guide for ADC evaluation

DC 851

DC 996

.

DC 890

0202

ANALOG

INPUT

S/H

AMP

LTC2208 ANALOG

SUMMATION

CLOCK/DUTY

CYCLE

CONTROL

ENC+ ENC-

CLKOUT

OF

D15

DO

16-BIT
PIPELINED
ADC CORE

PRECISION

DAC

DIGITAL

SUMMATION

OUTPUT

DRIVERS

MULTIBIT DEEP

PSEUDO-RANDOM

NUMBER

GENERATOR

DITH

DITHER ENABLE

HIGH = DITHER ON

LOW = DITHER OFF

AIN +

AIN -

}

Σ

CLKOUTCLKOUT

OF

OF

D15/DO

D15

D14/DO

D14

D2/DO

D2

D1/DO

D1

DO

RAND = HIGH,
SCRAMBLE,
ENABLED

DO

LT C22 09 AD C FA MI LY

LTC2209 High Performance ADC Family

•

Internal Transparent Dither

•

Data Output Randomizer

•

Single 3.3V Supply

•

PGA Front End (1.5V

•

LVDS or CMOS Outputs

•

Data Ready Output Clock

•

Optional Clock Duty Cycle Stabilizer

•

64-pin 9mm × 9mm QFN Package

The LTC2209 is our highest performance ADC family, targeting the most demanding wideband, low noise, signal acquisition applications,
while still offering the lowest power in the industry.

The LTC2209 and LTC2207 families incorporate two unique features that simplify digital receiver design and improve system performance.
The first is an internal transparent dither circuit that improves the ADC’s spurious free dynamic range (SFDR) response well beyond
100dBc for low level input signals. The second feature is a digital output randomizer that dramatically reduces unwanted tones caused by
digital feedback.

The DC854D demo board family offers CMOS output evaluation, while DC996B is configured for LVDS outputs.

Applications: Software Defined Radio, Spectrum Analyzer, Oscilloscope, MRI, GPS, Avionics Instrumentation, Radar and Satellite
Communications, Servowriter, CCD Tester, RFID, Disk Drive Tester, Radiography, RF Power Meter

P-P

or 2.25V

P-P

)

left: DC 996, right: DC 890

Part Number Resolution Speed SNR SFDR

Full Power
Bandwidth

Power
Dissipation

LTC2209 16-Bit 160Msps 77.1dB 100dB 700MHz 1450mW

LTC2208 16-Bit 130Msps 77.7dB 100dB 700MHz 1250mW

LTC2209-14 14-Bit 160Msps 76.8dB 98dB 700MHz 1450mW

LTC2208-14 14-Bit 130Msps 77.1dB 98dB 700MHz 1320mW

LT C22 07 AD C FA MI LY

LTC2207 High Performance ADC Family

•

Internal Transparent Dither

•

Data Output Randomizer

•

Single 3.3V Supply

•

PGA Front End

•

CMOS Outputs

•

Data Ready Output Clock

•

Clock Duty Cycle Stabilizer

•

48-pin 7mm × 7mm QFN Package

The LTC2202 through LTC2207 family of high speed ADCs use the DC718B USB board to interface between the demo board and a PC.
Currently, two demo boards are available. The DC918C, with its AC-coupled analog inputs and differential clock input, targets the
LTC2204 through the LTC2207. The DC919A offers the choice of DC- or AC-coupled analog inputs and has a single-ended clock input for
the LTC2202/LTC2203. The LTC2205-LTC2207 ADCs can be evaluated using the DC-coupled DC919A, but the single-ended clock
will slightly degrade performance.

Applications: Oscilloscope, MRI, IR and CCD Cameras, Bomb Detection, Spectroscopy, Disk Drive Tester

left: DC 919, right: DC 718

0303

Part Number Resolution Speed SNR SFDR

Full Power
Bandwidth

Power
Dissipation

LTC2207 16-Bit 105Msps 77.9dB 100dB 700MHz 900mW

LTC2206 16-Bit 80Msps 77.9dB 100dB 700MHz 725mW

LTC2205 16-Bit 65Msps 79.0dB 100dB 700MHz 610mW

LTC2204 16-Bit 40Msps 79.1dB 100dB 700MHz 480mW

LTC2203 16-Bit 25Msps 81.6dB 100dB 380MHz 220mW

LTC2202 16-Bit 10Msps 81.6dB 100dB 380MHz 140mW

LTC2207-14 14-Bit 105Msps 77.3dB 98dB 700MHz 947mW

LTC2206-14 14-Bit 80Msps 77.3dB 98dB 700MHz 762mW

LTC2205-14 14-Bit 65Msps 78.3dB 98dB 700MHz 600mW

0204

LT C22 20 - 1 A ND LTC 22 42 - 12 FA M ILI ES

LTC2220-1 and LTC2242-12 High IF Sampling ADC Families

•

Single 3.3V or 2.5V Supply

•

LVDS or CMOS Outputs

•

Data Ready Output Clock

•

Selectable 1V

•

Clock Duty Cycle Stabilizer

•

64-pin 9mm × 9mm QFN Package

The 3.3V LTC2220-1 family is pin-compatible with the 2.5V LTC2242-12 family of ADCs, sampling up to 250Msps at 12 bits.
The LTC2242-12 offers higher sampling rates at lower power dissipation for multichannel applications. With a 1.2GHz full power
bandwidth, undersampling at IFs as high as 1GHz are achievable. The CMOS outputs can be demultiplexed by a factor of two to
reduce the data rate for data collection and processing in FPGAs.

Applications: Cable Headend Systems, CATV Return Path Digitizer, Power Amplifier Linearization, Data Acquisition, Disk Drive Tester,
Multichannel Receivers, Radar and Jammers, GPS, High Definition Video, Laser Range Finders, Telemetry, Frequency Synthesizer,
BTS Microwave Link, Wafer Defect Detection

P-P

or 2V

Input Range

P-P

left: DC 997, right: DC 890

Part Number Resolution Speed SNR SFDR

Full Power
Bandwidth

Power
Dissipation

LTC2220-1 12-Bit 185Msps 67.7dB 80dB 775MHz 910mW

LTC2220 12-Bit 170Msps 67.7dB 84dB 775MHz 890mW

LTC2221 12-Bit 135Msps 67.8dB 84dB 775MHz 660mW

LTC2230 10-Bit 170Msps 61.2dB 78dB 775MHz 890mW

LTC2231 10-Bit 135Msps 61.2dB 78dB 775MHz 660mW

Part Number Resolution Speed SNR SFDR

Full Power
Bandwidth

Power
Dissipation

LTC2242-12 12-Bit 250Msps 65.4dB 78dB 1.2GHz 740mW

LTC2241-12 12-Bit 210Msps 65.5dB 78dB 1.2GHz 585mW

LTC2240-12 12-Bit 170Msps 65.6dB 80dB 1.2GHz 445mW

LTC2242-10 10-Bit 250Msps 60.6dB 78dB 1.2GHz 740mW

LTC2241-10 10-Bit 210Msps 60.6dB 78dB 1.2GHz 585mW

LTC2240-10 10-Bit 170Msps 60.6dB 80dB 1.2GHz 445mW

LTC2224 ADC FAMILY

LTC2224 High IF Sampling ADC Family

•

Single 3.3V Supply

•

CMOS Outputs

•

Data Ready Output Clock

•

Selectable 1V

•

Clock Duty Cycle Stabilizer

•

48-pin 7mm × 7mm QFN Package

This high speed family is optimized for multicarrier wireless basestation transceiver applications for all major air interfaces including GSM,
CDMA, WCDMA (UMTS), TD-SCDMA and WiMAX.

Applications: PA Linearization, WiMAX Radio, Satellite Communications, CATV Return Path, Wireless Modem, Flow and Jitter Meters,
Missile Guidance System, Plasma Generator, DVD Equipment, Battery Monitor, Fiber Optic Gyro, Blood Analyzer, Digital Oscilloscope

P-P

or 2V

Input Range

P-P

left: DC 751, right: DC 718

03

05

Part Number Resolution Speed SNR SFDR

Full Power
Bandwidth

Power
Dissipation

LTC2224 12-Bit 135Msps 67.6dB 84dB 775MHz 630mW

LTC2222 12-Bit 105Msps 68.4dB 84dB 775MHz 475mW

LTC2223 12-Bit 80Msps 68.5dB 84dB 775MHz 366mW

LTC2222-11 11-Bit 105Msps 65.7dB 84dB 775MHz 475mW

LTC2234 10-Bit 135Msps 61.2dB 78dB 775MHz 630mW

LTC2232 10-Bit 105Msps 61.3dB 78dB 775MHz 475mW

LTC2233 10-Bit 80Msps 61.3dB 78dB 775MHz 366mW

0206

LT C22 55 AD C FA MI LY

LTC2255 Lowest Power ADC Family

•

Single 3V Supply

•

CMOS Outputs

•

Single-Ended Clock Input

•

Selectable 1V

•

Clock Duty Cycle Stabilizer

•

32-pin 5mm × 5mm QFN Package

P-P

or 2V

Input Range

P-P

left: DC 782, right: DC 718

The combination of high performance and low power makes this family ideal for battery-powered, test and measurement equipment.

Applications: WiMAX, Software Defined Radio, CCD and Thermal Imaging, MRI Equipment, Industrial Camera, Ultrasound, Radar,
Spectroscopy, Handheld Instrumentation, RFID

Part Number Resolution Speed SNR SFDR

Full Power
Bandwidth

Power
Dissipation

LTC2255 14-Bit 125Msps 72.5dB 88dB 640MHz 395mW

LTC2254 14-Bit 105Msps 72.4dB 88dB 640MHz 320mW

LTC2249 14-Bit 80Msps 73.0dB 90dB 575MHz 222mW

LTC2248 14-Bit 65Msps 74.3dB 90dB 575MHz 204mW

LTC2247 14-Bit 40Msps 74.4dB 90dB 575MHz 120mW

LTC2246 14-Bit 25Msps 74.5dB 90dB 575MHz 75mW

LTC2245 14-Bit 10Msps 74.4dB 90dB 575MHz 60mW

LTC2253 12-Bit 125Msps 70.2dB 88dB 640MHz 395mW

LTC2252 12-Bit 105Msps 70.2dB 88dB 640MHz 320mW

LTC2229 12-Bit 80Msps 70.6dB 90dB 575MHz 211mW

LTC2228 12-Bit 65Msps 71.3dB 90dB 575MHz 204mW

LTC2227 12-Bit 40Msps 71.4dB 90dB 575MHz 120mW

LTC2226 12-Bit 25Msps 71.4dB 90dB 575MHz 75mW

LTC2225 12-Bit 10Msps 71.3dB 90dB 575MHz 60mW

LTC2251 10-Bit 125Msps 61.6dB 85dB 640MHz 395mW

LTC2250 10-Bit 105Msps 61.6dB 85dB 640MHz 320mW

LTC2239 10-Bit 80Msps 61.6dB 85dB 575MHz 211mW

LTC2238 10-Bit 65Msps 61.8dB 85dB 575MHz 204mW

LTC2237 10-Bit 40Msps 61.8dB 85dB 575MHz 120mW

LTC2236 10-Bit 25Msps 61.8dB 85dB 575MHz 75mW

LT C22 85 DU A L ADC F A MILY

LTC2285 Lowest Power Dual ADC Family

•

Single 3V Supply

•

-110dB Channel-to-Channel Crosstalk

•

CMOS Outputs

•

Single-Ended Clock Input

•

Selectable 1V

•

Clock Duty Cycle Stabilizer

•

64-pin 9mm × 9mm QFN Package

The LTC2285 dual ADC family offers exceptionally low crosstalk between channels of -110dB, the best performance in the industry.
Each ADC has a separate single-ended input clock, which is combined on the evaluation boards for ease of evaluation. The duals can be
evaluated in their multiplexed output bus configuration using the DC816 family, but the MUX feature is limited to 65Msps per channel.
The DC851 family demultiplexed (parallel) output demo board allows for evaluation of the entire family of dual ADCs.

Applications: Antenna Diversity, RFID, WiMAX Basestation, Phased Array Multichannel Radio, Non-Destructive Testing, Software Defined
Radio, Collision Avoidance Systems, Wireless Microphone, Night Vision Goggles, NTSC Video Digitizer

P-P

or 2V

Input Range

P-P

left: DC 851, right: DC 890

0307

Part Number Resolution Speed SNR SFDR

Full Power
Bandwidth

Power
Dissipation

LTC2285 14-Bit 125Msps 72.4dB 88dB 640MHz 790mW

LTC2284 14-Bit 105Msps 72.4dB 88dB 575MHz 540mW

LTC2299 14-Bit 80Msps 73.0dB 90dB 575MHz 444mW

LTC2298 14-Bit 65Msps 74.3dB 90dB 575MHz 400mW

LTC2297 14-Bit 40Msps 74.4dB 90dB 575MHz 235mW

LTC2296 14-Bit 25Msps 74.5dB 90dB 575MHz 150mW

LTC2295 14-Bit 10Msps 74.4dB 90dB 575MHz 120mW

LTC2283 12-Bit 125Msps 70.2dB 88dB 640MHz 790mW

LTC2282 12-Bit 105Msps 70.1dB 88dB 575MHz 540mW

LTC2294 12-Bit 80Msps 70.6dB 90dB 575MHz 422mW

LTC2293 12-Bit 65Msps 71.3dB 90dB 575MHz 400mW

LTC2292 12-Bit 40Msps 71.4dB 90dB 575MHz 235mW

LTC2291 12-Bit 25Msps 71.4dB 90dB 575MHz 150mW

LTC2290 12-Bit 10Msps 71.3dB 90dB 575MHz 120mW

LTC2281 10-Bit 125Msps 61.6dB 85dB 640MHz 790mW

LTC2280 10-Bit 105Msps 61.6dB 85dB 575MHz 540mW

LTC2289 10-Bit 80Msps 61.6dB 85dB 575MHz 422mW

LTC2288 10-Bit 65Msps 61.8dB 85dB 575MHz 400mW

LTC2287 10-Bit 40Msps 61.8dB 85dB 575MHz 235mW

LTC2286 10-Bit 25Msps 61.8dB 85dB 575MHz 150mW

0208

LT C17 50 AD C FA MI LY

LTC1750 High Performance 5V ADC Family

•

Single 5V Supply

•

CMOS Outputs

•

Data Ready Output Clock

•

Selectable Input Ranges (Varied)

•

48-pin TSSOP Package

left: DC 520, right: DC 718

The LTC1750 and LTC1749 are high IF sampling ADCs up to 500MHz IF, while the rest of the family is best suited for IFs below 250MHz.
This pin-compatible family provides excellent SNR performance from a 5V supply.

Applications: PA Linearization, ATE, Instrumentation, Video Equipment, Particle Monitoring Equipment, Cardiac Ultrasound,
CMOS Imaging, Digital Communications Simulator, Cell Sorter, Broadcast Camera, Data Acquisition

Part Number Resolution Speed SNR SFDR

Full Power
Bandwidth

Power
Dissipation

LTC1750 14-Bit 80Msps 75.5dB 90dB 500MHz 1450mW

LTC1748 14-Bit 80Msps 76.3dB 90dB 240MHz 1400mW

LTC1742 14-Bit 65Msps 76.5dB 90dB 240MHz 1275mW

LTC1746 14-Bit 25Msps 77.5dB 91dB 240MHz 390mW

LTC1749 12-Bit 80Msps 71.8dB 87dB 500MHz 1450mW

LTC1747 12-Bit 80Msps 72.0dB 85dB 240MHz 1400mW

LTC1741 12-Bit 65Msps 72.0dB 85dB 240MHz 1275mW

LTC1743 12-Bit 50Msps 72.5dB 85dB 150MHz 1000mW

LTC1745 12-Bit 25Msps 72.5dB 96dB 240MHz 380mW

Fully Differential ADC Drivers

LT1994

16-bit

LT6404-X

LT6600-X

LT6402-X

LT6411

LTC6406

LT1993-X

LTC6401-X

LTC6400-X

300MHz200MHz

Input Frequency Range

100MHzDC

Resolut io n

Linear Technology offers a wide range of fully differential
amplifiers optimized for driving high-speed ADCs.
They provide a wide variety of features, including
built-in gain-setting resistors and integrated single pole
filters, 4th order integrated filters, and the wide common
mode input range. These amplifiers can also easily convert
single-ended inputs to differential outputs.

FULLY DIFFERENTIAL ADC DRIVERS

0309

Product

Input Frequency
Range Gain Range

Distortion
HD2/HD3 Noise Is Vs

Price
(1,000 pcs) Features

LT1994 DC to 2MHz Resistor-set -96dBc @ 1MHz 3 nV/√Hz 13.3mA 2.4V to 12.6V $1.65 RR Output

LT6600-2.5 DC to 2.5MHz Resistor-set -88dBc @ 1MHz 23 nV/√Hz 26mA 3V to 11V $2.95 Integrated

4th order filter
fc = 2.5MHz

LT6600-5 DC to 5MHz Resistor-set -93dBc @ 1MHz 16 nV/√Hz 28mA 3V to 11V $2.95 Integrated

4th order filter
fc = 5MHz

LTC6403-1 DC to 5MHz Resistor-set -95dBc @ 3MHz 2.8 nV/√Hz 11mA 2.7V to 5.25V TBD RR Output

LTC6404-1 DC to 10MHz Resistor-set -92dBc @ 10MHz 1.5 nV/√Hz 27mA 2.7V to 5.5V $3.44 RR Output

LTC6404-2 DC to 15MHz Resistor-set -98dBc @ 10MHz 1.5 nV/√Hz 30mA 2.7V to 5.25V $3.44 Min Gain = 2V/V

LT6600-10 DC to 10MHz Resistor-set -88dBc @ 1MHz 14 nV/√Hz 35mA 3V to 11V $2.95 Integrated

4th order filter
fc = 10MHz

LT6600-15 DC to 15MHz Resistor-set -86dBc @ 1MHz 19 nV/√Hz 35mA 3V to 11V $2.95 Integrated

4th order filter
fc = 15MHz

LT6600-20 DC to 20MHz Resistor-set -83dBc @ 2.5MHz 15 nV/√Hz 42mA 3V to 11V $2.95 Integrated

4th order filter
fc = 20MHz

LT6402-6 DC to 30MHz 6dB -84dBc @ 25MHz 3.9 nV/√Hz 30mA 4V to 5.5V $2.39 1st order filter

LT6402-12 DC to 30MHz 12dB -82dBc @ 25MHz 2.6 nV/√Hz 30mA 4V to 5.5V $2.39 1st order filter

LT6402-20 DC to 30MHz 20dB -80dBc @ 25MHz 1.9 nV/√Hz 30mA 4V to 5.5V $2.39 1st order filter

LT6411 DC to 50MHz 0dB, 6dB -76dBc @ 10MHz 7.7 nV/√Hz 8mA 4.5V to 12.5V $2.39 Fixed Gain

LTC6406 DC to 50MHz Resistor-set -72dBc @ 50MHz 1.6 nV/√Hz 18mA 2.7V to 3.5V $3.44 RR Input

LT1993-2 DC to 70MHz 6dB -70dBc @ 70MHz 3.8 nV/√Hz 100mA 4V to 5.5V $2.95 1st order filter

LT1993-4 DC to 70MHz 12dB -73dBc @ 70MHz 2.4 nV/√Hz 100mA 4V to 5.5V $2.95 1st order filter

LT1993-10 DC to 70MHz 20dB -70dBc @ 70MHz 1.9 nV/√Hz 100mA 4V to 5.5V $2.95 1st order filter

LTC6401-8 DC to 140MHz 8dB -87dBc @ 70MHz 3.2 nV/√Hz 45mA 2.85V to 3.5V $2.95 1st order filter

LTC6401-20 DC to 140MHz 20dB -88dBc @ 70MHz 2.1 nV/√Hz 50mA 2.85V to 3.5V $2.95 1st order filter

LTC6401-26 DC to 140MHz 26dB -81dBc @ 70MHz 1.5 nV/√Hz 45mA 2.85V to 3.5V $2.95 1st order filter

LTC6400-20 DC to 300MHz 20dB -76dBc @ 140MHz 2.1 nV/√Hz 90mA 2.85V to 3.5V $3.20 1st order filter

LTC6400-26 DC to 300MHz 26dB -81dBc @ 140MHz 1.5 nV/√Hz 85mA 2.85V to 3.5V $3.20 1st order filter

0210 FULLY DIFFERENTIAL ADC DRIVERS

LTC6400 High Speed Fully Differential ADC Driver Family

Integrated Gain-Setting Resistors:

• LTC6400-8 8dB

• LTC6400-14 14dB

• LTC6400-20 20dB

• LTC6400-26 26dB

High Performance (LTC6400-20):

• 1.8GHz GBW

• 4500V/us Slew Rate

• 41 dBm OIP3 @ 240MHz

• -74dBc IMD3 @ 240MHz

• 1.9nV/√Hz Op Amp Noise

•

Integrated First-Order Filter

•

Independent Output Common Mode Control

•

3mm × 3mm QFN Package

•

Lower Power, Lower Speed LTC6401 Available

LTC6400

The LTC6400 high-speed fully differential amplifier family achieves high performance while simplifying system design. Capable of driving
up to 300MHz signals with low noise and distortion, the LTC6400 has integrated gain-setting resistors, adjustable output filtering, and
flexible I/O coupling. This integration maximizes performance and simplifies board design. Fully specified at 3V supply, the LTC6400
can often share the same supply rail with the ADC.

LTC6404-1 High-Resolution Fully Differential ADC Driver Family

•

Low Noise: 1.5nV/√Hz

•

Very Low Distortion: < -90dBc @ 10MHz

•

Closed Loop -3dB Bandwidth: 600MHz

•

450V/us Slew Rate

•

Independent Output Common Mode Control

•

3mm × 3mm QFN Package

•

Lower power, Lower Speed LTC6403 Available

•

2.7V to 5.25V Supply Voltage Range

LTC6404

The LTC6404-1 is capable of driving 10MHz input signals into today’s state-of-the-art high-speed 14- to 18-bit ADCs while operating on
the same supply voltage. It draws only 27mA and features a hardware shutdown mode which reduces current consumption to 0.25mA.

LTC2284

OV

DD

OGND

0.1uF

1.4V

1.2V

1K

1.0V

0.1uF 0.1uF

1K

50ohm Transmission Line

Shared Reference Line

Close and Same Ground

LVDS Receiver

IN+

IN-

43ohm

CMOS VS LVDS OUTPUTS

CMOS vs LVDS Outputs

Low-Voltage Differential Signaling (LVDS) is often preferred as a means to reduce ground currents and radiated noise when sampling at
speeds greater than 100Msps. LVDS allows for good common-mode noise rejection at the digital receiver and faster switching rates.
The lower signaling levels allow properly terminated transmission paths which are of paramount importance in maintaining good
signal integrity.

CMOS obliges you to use source termination (provided internally on Linear Technology high-speed ADCs) but this is still not ideal as there
is some lumped capacitance after the internal resistor. Single-ended CMOS outputs have longer rise and fall times that limit the maximum
bit rate due to the larger voltage swing and are potentially more sensitive to crosstalk and above all, ground bounce.

However, LVDS is not completely immune to noise. The CMRR of receivers is not more than 20-30dB at higher frequencies, and the
signaling levels are lower. Adjacent lines routed in close proximity will still result in crosstalk. The presence of a high level CMOS signal
routed alongside an LVDS pair will potentially compromise signal integrity. In addition, high speed ADCs using LVDS can require up to a
quarter Watt more power than CMOS.

An advantage of Linear Technology’s high-speed ADCs is the ability to reduce the digital output supply (OV
low-voltage CMOS outputs. Lowering the CMOS levels greatly reduces the resulting noise and also helps reduce digital feedback. For
routing short distances, buffering can be eliminated at the ADC output for direct connection to an FPGA or DSP without discernable
performance degradation compared to LVDS. However, if there is ground bounce in the FPGA as a result of activity at asynchronous
or subharmonic frequencies, the elimination of buffers may allow noise to be injected back into the ADC.

Another technique that can be used to reduce digital noise is to configure the part in a Pseudo-LVDS output mode where the outputs are
configured as CMOS but OV

is biased at 1.4V and OGND at 1V (see Figure 1). The outputs are then run into a standard LVDS receiver.

DD

This requires a bypassed 1.2V reference voltage near the ADC, and needs to represent similar source impedance to the driven line at the
receiver. If these lines are routed over a belt of copper that is biased at the ADC, it may offer many of the advantages of LVDS without
the power consumption in the ADC.

Figure 1 also shows the integrated series resistance included on every digital output so that each output appears as 50ohms.

) as low as 0.5V for running

DD

0311

Figure 1. Pseudo-LVDS Interface

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15 Research Place
North Chelmsford, MA 01863
Tel: [phone]
Fax: [phone]

Connecticut

Tel: [phone]

Philadelphia

3220 Tillman Dr., Ste. 120
Bensalem, PA 19020
Tel: [phone]
Fax: [phone]

SOUTHEAST AREA

Atlanta

Tel: [phone]

Austin

8500 N. Mopac, Ste. 603
Austin, TX 78759
Tel: [phone]
Fax: [phone]

Dallas

17000 Dallas Pkwy., Ste. 200
Dallas, TX 75248
Tel: [phone]
Fax: [phone]

Fort Lauderdale

Tel: [phone]

Houston

1080 W. Sam Houston Pkwy., Ste. 225
Houston, TX 77043
Tel: [phone]
Fax: [phone]

Huntsville

Tel: [phone]

Orlando

Tel: [phone]

Raleigh

15100 Weston Pkwy., Ste. 202
Cary, NC 27513
Tel: [phone]
Fax: [phone]

Tampa

Tel: [phone]

CH IN A

Linear Technology Corp. Ltd.

Units 1503-04, Metroplaza Tower 2
223 Hing Fong Road
Kwai Fong, N.T., Hong Kong
Tel: [phone]
Fax: [phone]

Linear Technology Corp. Ltd.

Room 902, Evergo Tower
1325 Huaihai M. Road
Shanghai, 200031, PRC
Tel: [phone]
Fax: [phone]

Linear Technology Corp. Ltd.

Room 816, 8/F
China Electronics Plaza B
No. 3 Dan Ling Rd., Hai Dian District
Beijing, 100080, PRC
Tel: [phone]
Fax: [phone]

Linear Technology Corp. Ltd.

Room 2604, 26/F
Excellence Times Square Building
4068 YiTian Road, Futian District
Shenzhen, 518048, PRC
Tel: [phone]
Fax: [phone]

JAPAN

Linear Technology KK

8F Shuwa Kioicho Park Bldg.
3-6 Kioicho Chiyoda-ku
Tokyo, 102-0094, Japan
Tel: [phone]
Fax: [phone]

Linear Technology KK

6F Kearny Place Honmachi Bldg.
1-6-13 Awaza, Nishi-ku
Osaka-shi, 550-0011, Japan
Tel: [phone]
Fax: [phone]

Linear Technology KK

7F, Sakuradori Ohtsu KT Bldg.
3-20-22 Marunouchi, Naka-ku Nagoya-shi,
460-0002, Japan
Tel: [phone]
Fax: [phone]

KOREA

Linear Technology Korea Co., Ltd.

Yundang Building, #1002
Samsung-Dong 144-23
Kangnam-Ku, Seoul
135-090 Korea
Tel: [phone]
Fax: [phone]

SINGAPORE

Linear Technology Pte. Ltd.

507 Yishun Industrial Park A
Singapore 768734
Tel: [phone]
Fax: [phone]

TAIWAN

Linear Technology Corporation

8F-1, 77, Nanking E. Rd., Sec. 3
Taipei, Taiwan
Tel: [phone]
Fax: [phone]

FINLAND

Linear Technology AB

Teknobulevardi 3-5
P.O. Box 35
FIN-01531 Vantaa
Finland
Tel: [phone]
Fax: [phone]

FRANCE

Linear Technology S.A.R.L.

Parc Tertiaire Silic
2 Rue de la Couture, BP10217
94518 Rungis Cedex
France
Tel: [phone]
Fax: [phone]

GERMANY

Linear Technology GmbH

Osterfeldstrasse 84, Haus C
D-85737 Ismaning
Germany
Tel: [phone]
Fax: [phone]

Linear Technology GmbH

Haselburger Damm 4
D-59387 Ascheberg
Germany
Tel: [phone]
Fax: [phone]

Linear Technology GmbH

Jesinger Strasse 65
D-73230 Kirchheim/Teck
Germany
Tel: [phone]
Fax: [phone]

ITALY

Linear Technology Italy Srl

Orione 3, C.D. Colleoni
Via Colleoni, 17
I-20041 Agrate Brianza (MI)
Italy
Tel: [phone]
Fax: [phone]

SWEDEN

Linear Technology AB

Electrum 204
Isafjordsgatan 22
SE-164 40 Kista
Sweden
Tel: [phone]
Fax: [phone]

UNITED KINGDOM

Linear Technology (UK) Ltd.

3 The Listons, Liston Road
Marlow, Buckinghamshire SL7 1FD
United Kingdom
Tel: [phone]
Fax: [phone]

Linear Technology Corporation

1630 McCarthy Blvd.
Milpitas, CA 95035-7417
Tel: 1-800-4-LINEAR
408-432-1900
Fax: [phone]

www.linear.com

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