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Design Notes

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  A-to-D Converter Does Frequency Translation &mdash DN259
  PDF, 93 Kb, File published: Jun 1, 2001
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  A-to-D Converter Does Frequency Translation – Design Note 259
  Derek Redmayne
  The need to characterize frequency sources, both in the
  laboratory and in the п¬Ѓeld, is increasingly important. The
  circuit in Figure 1 offers some interesting attributes in
  a compact and relatively inexpensive scheme. It uses
  an LTC В®1420 ADC to undersample a higher frequency,
  driving an LTC1668 DAC, followed by a п¬Ѓlter to perform a
  down conversion. The output of the п¬Ѓlter is subsequently
  resampled to produce a manageable sample rate for a
  single-chip microcontroller. In addition to characterizing
  the carrier in an IF strip or the output of a local oscillator,
  this technique is also useful for characterizing ADCs,
  DACs, clock sources, signal sources or the effects of
  logic devices or phase-locked loops on phase noise.
  Frequency conversion or translation is usually performed by a diode mixer or a Gilbert cell mixer. Down
  conversion is most often encountered in radio receivers;
  up conversion is more commonly used in transmitters. The common superheterodyne receiver usually
  involves one conversion to produce a п¬Ѓxed intermediate
  frequency (IF). Spectrum analyzers, cellular base stations, cable modems, microwave and satellite receivers,
  radar and optical communications systems all include
  frequency conversion blocks. Down Conversion with an ADC
  It may not be commonly known that down conversion …

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  High Performance Op Amps Deliver Precision Waveform Synthesis &mdash DN306
  PDF, 86 Kb, File published: Mar 2, 2003
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  High Performance Op Amps Deliver Precision Waveform
  Synthesis – Design Note 306
  Jon Munson
  Introduction
  With the trend toward ever more precise waveform
  generation using DSP synthesis and digital-to-analog
  conversion, such as with the LTCВ®1668 16-bit, 50Msps
  DAC, increasing demands are being placed on the output
  amplifier. In some applications, the DAC current-tovoltage function is simply resistive, though this is limited
  to small-signal situations. The more common solution
  is to use an amplification or a transimpedance stage
  to provide larger usable scale factors or level shifting.
  Figure 1 shows one such example, with an LTВ®1722
  performing a differential-current to single-ended voltage amplification for an LTC1668.
  The LT1722, LT1723 and LT1724 Low Noise
  Amplifiers
  The LT1722, LT1723 and LT1724 are single, dual and
  quadruple operational amplifiers that feature low noise
  and high speed along with miserly power consumption.
  The parts are optimized for low voltage operation and
  draw only 3.7mA (typical) per section from В±5V supplies,
  yet deliver up to 200MHz GBW and quiet 3.8nV/в€љHz, 1.2pA/в€љHz (typical) noise performance. DC characteristics include sub-millivolt input offset precision and
  output drive greater than 20mA, excellent for cable …

Articles

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  High Performance Op Amps Deliver Precision Waveform Synthesis &mdash LT Journal
  PDF, 148 Kb, File published: Aug 9, 2004
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  DESIGN IDEAS High Performance Op Amps Deliver
  Precision Waveform Synthesis
  by Jon Munson
  Introduction
  With the trend toward ever more precise waveform generation using DSP
  synthesis and digital-to-analog conversion, such as with the LTC1668
  16-bit, 50Msps DAC, increasing demands are being placed on the output
  amplifier. In some applications, the
  DAC current-to-voltage function is
  simply resistive, though this is limited to small-signal situations. The
  more common solution is to use an
  amplification or a transimpedance
  stage to provide larger usable scale
  factors or level shifting. Figure 1 shows
  one such example, with an LT1722
  performing a differential-current to
  single-ended-voltage amplification for
  an LTC1668. 18pF 1k 49.9Ω 5V 0.1µF 49.9Ω IOUTA 20 200Ω IOUTB 200Ω
  19 IFS = 5mA 18pF 1 LT1722
  2 1k
  –5V consumption. The parts are optimized
  for low voltage operation and draw
  only 3.7mA (typical) per section from …

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  LTC1668 DAC and LT1807 Op Amp Achieve 90ns Settling to 16 Bits and 83dB SFDR in a Small Footprint &mdash LT Journal
  PDF, 169 Kb, File published: Sep 1, 2001
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  DESIGN IDEAS LTC1668 DAC and LT1807 Op Amp
  Achieve 90ns Settling to 16 Bits and
  83dB SFDR in a Small Footprint
  by Glen Brisebois, Ken Haastrup and Derek Redmayne
  The LTC1668 is a new 16-bit,
  50Msps differential, current output
  DAC in a small SSOP package. It has
  a 10mA full-scale output and a 1V
  output compliance and it achieves
  20ns settling to 0.1% into 50Ω loads.
  The LT1807 is a 325MHz, 140V/Вµs
  precision, low noise dual op amp available in a small MSOP package. Its
  combination of precision, low noise,
  high bandwidth and fast slew rate
  make it ideal for high performance
  signal conditioning and acquisition
  systems. Together, these components
  create a fast, precise, versatile, low
  distortion VOUT DAC with minimal
  PCB space requirements.
  The circuit in Figure 1 shows the
  LT1807 applied as a dual I/V converter to extend the LTC1668’s
  effective output compliance. With …

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  New 16-Bit 50Msps DAC Offers Highest AC and DC Performance &mdash LT Journal
  PDF, 334 Kb, File published: Sep 1, 2001
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  LINEAR TECHNOLOGY
  SEPTEMBER 2001 IN THIS ISSUE…
  COVER ARTICLE
  New 16-Bit 50Msps DAC Offers
  Highest AC and DC Performance . 1
  James L. Brubaker and William C. Rempfer Issue Highlights . 2
  LTCВ® in the News . 2
  DESIGN FEATURES
  A Thermoelectric Cooler Temperature
  Controller for Fiber Optic Lasers . 5
  Jim Williams
  В® LT 1681 and LTC1698 Team Up to
  Provide a Complete Solution
  for 48V Input, 2-Transistor
  Synchronous Forward Converters
  . 9
  Kurk Mathews High Efficiency, Low Cost Power
  Supply Meets Intel Mobile Voltage
  Positioning Requirements . 13
  Wei Chen, Peter Guan and David Chen Two New Switching Regulators
  Deliver Both Power
  and Ultralow Noise . 18
  Rick Brewster Adjustable Low-Battery Threshold …

Model Line

Manufacturer's Classification

• Data Conversion > Digital-to-Analog Converters (DAC) > High Speed DACs | Unipolar Digital-to-Analog Converters (DAC)