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Application Notes

• Download
  High Voltage, Low Noise, DC/DC Converters &mdash AN118
  PDF, 2.6 Mb, File published: Mar 28, 2008
  Photomultipliers (PMT), avalanche photodiodes (APD), ultrasonic transducers, capacitance microphones, radiation detectors and similar devices require high voltage, low current bias. Additionally, the high voltage must be pristinely free of noise; well under a millivolt is a common requirement with a few hundred microvolts sometimes necessary. Normally, switching regulator configurations cannot achieve this performance level without employing special techniques. One aid to achieving low noise is that load currents rarely exceed 5mA. This freedom permits output filtering methods that are usually impractical.
  Extract from the document

  Application Note 118
  March 2008
  High Voltage, Low Noise, DC/DC Converters
  A Kilovolt with 100 Microvolts of Noise
  Jim Williams This publication describes a variety of circuits featuring
  outputs from 200V to 1000V with output noise below 100ВµV
  measured in a 100MHz bandwidth. Special techniques
  enable this performance, most notably power stages
  optimized to minimize high frequency harmonic content.
  Although sophisticated, all examples presented utilize
  standard, commercially available magnetics—no custom
  components are required. This provision is intended to
  assist the user in quickly arriving at a produceable design.
  Circuits and their descriptions are presented beginning
  with the next ink.
  BEFORE PROCEEDING ANY FURTHER, THE READER
  IS WARNED THAT CAUTION MUST BE USED IN THE
  CONSTRUCTION, TESTING AND USE OF THE TEXT’S
  CIRCUITS. HIGH VOLTAGE, LETHAL POTENTIALS ARE
  PRESENT IN THESE CIRCUITS. EXTREME CAUTION
  MUST BE USED IN WORKING WITH, AND MAKING
  CONNECTIONS TO, THESE CIRCUITS. REPEAT: THESE
  CIRCUITS CONTAIN DANGEROUS, HIGH VOLTAGE …

• Download
  Video Circuit Collection &mdash AN57
  PDF, 559 Kb, File published: Jan 2, 1994
  AN57, the Video Circuit Collection, features a variety of video circuits designed at LTC. The LT1204 70MHz multiplexer is featured in a number of circuits which require excellent video isolation from channel to channel. High speed voltage and current feedback amplifiers are highlighted throughout the section on video processing circuits. There is a section on applying Current Feedback Amplifiers (CFAs) and a number of articles taken from the Linear Technology magazine.
  Extract from the document

  Application Note 57
  January 1994
  Video Circuit Collection
  Jon Munson and Frank Cox
  INTRODUCTION
  Even in a time of rapidly advancing digital image processing, analog video signal processing still remains eminently
  viable. The video A/D converters need a supply of properly
  amplified, limited, DC restored, clamped, clipped, contoured, multiplexed, faded and filtered analog video before
  they can accomplish anything. After the digital magic is
  performed, there is usually more amplifying and п¬Ѓltering
  to do as an adjunct to the D/A conversion process, not to mention all those pesky cables to drive. The analog way
  is often the most expedient and efficient, and you don’t
  have to write all that code.
  The foregoing is only partly in jest. The experienced engineer
  will use whatever method will properly get the job done;
  analog, digital or magic (more realistically, a combination
  of all three). Presented here is a collection of analog video
  circuits that have proven themselves useful. CIRCUIT INDEX
  I. Video Amplifier Selection Guide . 2 II. Video Cable Drivers . 3
  AC-Coupled Video Drivers . 3
  DC-Coupled Video Drivers . 4
  Clamped AC-Input Video Cable Driver . 5
  Twisted-Pair Video Driver and Receiver . 5 III. Video Processing Circuits . 6 …

• Download
  Linear Technology Magazine Circuit Collection, Volume III &mdash AN67
  PDF, 1.2 Mb, File published: Sep 1, 1996
  Application Note 67 is a collection of circuits for data conversion, interface and signal processing from the first five years of Linear Technology. This application note includes circuits such as fast video multiplexers for high speed video, an ultraselective bandpass filter circuit with adjustable gain, and a fully differential, 8-channel, 12-bit A/D system. The categories included in this app note are data conversion, interface, filters, instrumentation, video/op amps and miscellaneous circuits.
  Extract from the document

  Application Note 67
  September 1996
  Linear Technology Magazine Circuit Collection, Volume III
  Data Conversion, Interface and Signal Processing
  Richard Markell, Editor
  INTRODUCTION
  Application Note 67 is a collection of circuits from the first
  five years of Linear Technology, targeting data conversion,
  interface and signal processing applications. This
  Application Note includes circuits such as fast video
  multiplexers for high speed video, an ultraselective
  bandpass filter circuit with adjustable gain and a fully differential, 8-channel, 12-bit A/D system. The categories
  included herein are data conversion, interface, filters,
  instrumentation, video/op amps and miscellaneous
  circuits. Application Note 66, which covers power products
  and circuits from Linear Technology ’s first five years, is
  also available from LTC. ARTICLE INDEX
  Data Conversion . 3
  Fully Differential, 8-Channel, 12-Bit A/D System Using the LTCВ®1390 and LTC1410 . 3
  12-Bit DAC Applications . 5
  LTC1329 Micropower, 8-Bit, Current Output DAC Used for Power Supply Adjustment,
  Trimmer Pot Replacement . 7
  12-Bit Cold Junction Compensated, Temperature Control System with Shutdown . 8 …

• Download
  A Monolithic Switching Regulator with 100ВµV Output Noise &mdash AN70
  PDF, 1.7 Mb, Language: en, File published: Oct 1, 1997
  This publication details circuitry and applications considerations for the LT1533 low noise switching regulator. Eleven DC/DC converter circuits are presented, some offering <100µV output noise in a 100MHz bandwidth. Tutorial sections detail low noise DC/DC design, measurement, probing and layout techniques, and magnetics selection.
  Extract from the document

  Application Note 70
  October 1997
  A Monolithic Switching Regulator with 100ВµV Output Noise
  “Silence is the perfectest herald of joy .”
  Jim Williams INTRODUCTION
  Size, output flexibility and efficiency advantages have
  made switching regulators common in electronic apparatus. The continued emphasis on these attributes has
  resulted in circuitry with 95% efficiency that requires
  minimal board area. Although these advantages are welcome, they necessitate compromising other parameters. back to the driving source (“reflected” noise) and it is
  radiated. The multiple transmission paths combine with
  the high frequency content to make noise suppression
  difficult. Unconscionable amounts of bypass capacitors,
  ferrite beads, shields, Mu-metal and aspirin have been
  expended in attempts to ameliorate noise-induced effects. Switching Regulator “Noise”
  Something commonly referred to as “noise” is a primary
  concern. The switched mode power delivery that permits
  the aforementioned advantages also creates wideband
  harmonic energy. This undesirable energy appears as
  radiated and conducted components commonly labeled
  as “noise.” Actually, switching regulator output “noise” is
  not really noise at all, but coherent, high frequency residue
  directly related to the regulatorвЂ^TMs switching.1 Figure 1
  shows typical switching regulator output noise. Two distinct characteristics are present. The slow, ramping output …

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  A Seven-Nanosecond Comparator for Single Supply Operation &mdash AN72
  PDF, 882 Kb, File published: May 1, 1998
  AN72 is an extensive discussion of the causes and cures of problems in very high speed comparator circuits. A separate applications section uses the 7ns LT1394 in V-to-F converters, crystal oscillators, clock skew generators, triggers, sampling configurations and a nanosecond pulse stretcher. Appendices cover related topics.
  Extract from the document

  Application Note 72
  May 1998
  A Seven-Nanosecond Comparator
  for Single Supply Operation
  Guidance for Putting Civilized Speed to Work
  Jim Williams INTRODUCTION
  In 1985 Linear Technology Corporation introduced the
  LT В®1016 Comparator. This device was the first readily
  usable, high speed TTL comparator. Previous ICs were
  either too slow or unstable, preventing widespread
  acceptance. The LT1016 was, and is, a highly successful
  product.
  Recent technology trends have emphasized low power,
  single supply operation. The LT1016, although capable of
  such operation, does not include ground in its input range.
  As such, it must be biased into its operating common
  mode range for practical single supply use. A new device,
  the LT1394, maintains the speed and application civility of
  its predecessor while including ground in its input operating range. Additionally, the new comparator is faster and
  pulls significantly lower operating current than the LT1016.
  This publication borrows shamelessly from earlier LTC
  efforts, while introducing new material.1 It approximates,
  affixes, appends, abridges, amends, abbreviates, abrogates, ameliorates and augments the previous work.2 …

• Download
  Low Noise Varactor Biasing with Switching Regulators: Vanquishing Villainous Vitiators Vis-Г -Vis Vital Varactors &mdash AN85
  PDF, 490 Kb, File published: Aug 1, 2000
  Telecommunication, satellite links and set-top boxes all require tuning a high frequency oscillation. The actual tuning element, a varactor diode, requires high voltage bias for operation. The high voltage bias must be free of noise to prevent unwanted oscillator outputs. This publication details a method for generating noise free high voltage from low voltage inputs using switching regulators. Spurious oscillator outputs are below -90dBc. Suggested circuit and layout information is included. Appendices cover varactor diode theory and performance verification techniques.
  Extract from the document

  Application Note 85
  August 2000
  Low Noise Varactor Biasing with Switching Regulators
  Vanquishing Villainous Vitiators Vis-Г -Vis Vital Varactors
  Jim Williams and David Beebe
  INTRODUCTION “hyperabrupt” devices. Response modification is possible,
  with compromises in performance, particularly with regard
  to linearity and sensitivity.2 Telecommunication, satellite links and set-top boxes all
  require tuning a high frequency oscillator. The actual
  tuning element is a varactor diode, a 2-terminal device that
  changes capacitance as a function of reverse bias voltage.1 The oscillator is part of a frequency synthesizing
  loop, as detailed in Figure 1. A phase locked loop (PLL)
  compares a divided down representation of the oscillator
  with a frequency reference. The PLL’s output is level
  shifted to provide the high voltage necessary to bias the
  varactor, which closes a feedback loop by voltage tuning
  the oscillator. This loop forces the voltage controlled
  oscillator (VCO) to operate at a frequency determined by
  the frequency reference and the divider’s division ratio. Note 1. Theoretical considerations of varactor diodes are treated in
  Appendix A, “Zetex Variable Capacitance Diodes,” guest written by Neil
  Chadderton of Zetex.
  Note 2. The reader is again referred to Appendix A for in-depth discussion
  of varactor diodes. …

Design Notes

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  Video Circuits Collection &mdash DN57
  PDF, 79 Kb, File published: Apr 1, 1992
  Extract from the document

  Video Circuits Collection – Design Note 57
  William H. Gross
  Introduction
  This note shows how to make several different video
  circuits using high speed op amps. All of these circuits
  work with composite, RGB and monochrome video.
  For best results, bypass the power supply pins of
  these amplifiers with 1μF to 10μF tantalum capacitors
  in parallel with 0.01ОјF disc capacitors. It is important
  to terminate both ends of video cables to preserve
  frequency response. When properly terminated, the
  cable looks like a resistive load of 150О©.
  Lots of Inputs Video MUX Cable Driver (LT1227) Multiplex Amplifiers
  Often it is desirable to select one of several signals to
  send down a cable. Connecting the outputs of several
  amplifiers together and using the amplifier’s shutdown
  pin to disable all but one accomplishes this goal. The
  LTВ®1190, LT1191, LT1192, and LT1193 are shutdown by
  pulling pin 5 to the negative supply.
  The LT1223 and LT1227 current feedback amplifiers are
  shutdown by pulling Pin 8 to ground. During normal
  operation Pin 8 is open and at the positive supply potential. An easy way to interface Pin 8 to logic is with
  a logic level N-channel FET or a 74C906 (open-drain …

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  An Adjustable Video Cable Equalizer Using The LT1256 &mdash DN92
  PDF, 131 Kb, File published: Dec 1, 1994
  Extract from the document

  An Adjustable Video Cable Equalizer – Design Note 92
  Frank Cox
  This design note presents a voltage controlled cable
  equalizer based on the LTВ®1256 video fader. The circuit
  features ease of adjustment, simplicity and the capability
  for remote control. The amount of equalization can be
  adjusted continuously from the maximum allowed by the
  passive components to none at all. While the example
  shows video, this high performance equalizer can be
  used in any system using long runs of coaxial cable or
  twisted pair to transmit analog signals.
  A voltage or current controlled equalizer is essential in
  systems which automatically set cable compensation.
  In systems where cable equalization is set manually, a
  voltage controlled equalizer is still preferred as it does
  not require routing the signal path to the control. Instead, only a DC control voltage passes from the front
  panel to the equalizer.
  Automatic equalization is possible for properly characterized video cables. Maximum equalization is set to
  coincide with the maximum length of cable expected;
  the equalizer is controlled by a servo loop. One method
  of generating the necessary control voltage is to sample
  the color burst amplitude and compare this with a
  +V reference voltage using a summing integrator. Since the …

Articles

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  A Composite Amplifier Topology Wrings More Performance Out of the LTC1597 16-Bit Current Output DAC &mdash LT Journal
  PDF, 146 Kb, File published: Mar 1, 2002
  Extract from the document

  DESIGN IDEAS A Composite Amplifier Topology
  Wrings More Performance Out of the
  LTC1597 16-Bit Current Output DAC
  by Derek Redmayne
  The LTC1597 16-bit current output
  DAC is capable of settling in the neighborhood of 1.7Вµs to 2Вµs using the
  16-bit accurate LT1468 as an I-V
  converter1. For applications needing
  higher throughput such as in-circuit
  testing, electrostatic sorting of organic materials, or electrostatic
  actuation of MEMS as examples, 1Вµs
  settling seems to be a common goal.
  This article shows a composite
  amplifier that can achieve settling in
  1Вµs.
  The topology shown in Figure 1
  combines the low noise, low offset,
  low input current qualities of the
  LT1468, with the fast slewing output
  of the LT1227. The output of the first
  stage is still taken as the node that
  drives the compensation capacitor,
  but the second stage, the LT1227, …

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  Level Shift Allows CFA Video Amplifier to Swing to Ground on a Single Supply &mdash LT Journal
  PDF, 209 Kb, File published: Nov 1, 1998
  Extract from the document

  DESIGN IDEAS Level Shift Allows CFA Video Amplifier
  to Swing to Ground on a Single Supply
  by Frank Cox
  A current feedback (CFA) video
  amplifier can be made to run off a
  single supply and still amplify groundreferenced video with the addition of
  a simple and inexpensive level shifter.
  The circuit in Figure 1 is an amplifier
  and cable driver for a current output
  video DAC. The video can be composite or component but it must have
  sync. The single positive supply is
  12V but could be as low as 6V for the
  LT1227.
  The output of the LT1227 CFA
  used here can swing to within 2.5V of
  the negative supply with a 150Ω load
  over the commercial temperature
  range of 0В°C to 70В°C. Five diodes in
  the feedback loop are used, in conjunction with C5, to level shift the
  output to ground. The video from the
  output of the LT1227 charges C5 and
  the voltage across it allows the output
  to swing to ground or even slightly …

Model Line

Manufacturer's Classification

• Signal Conditioning > Amplifiers > Operational Amplifiers (Op Amps) > High Speed Amplifiers (GBW > 50MHz) | Low Noise Amplifiers ( | Current Feedback Amplifiers | High Voltage Amplifiers (>12V)
• Space & Harsh Environment > Military Hermetic (M)