Data Converter Testing Print  

Data converters fall into several categories. Here we will discuss two popular types, analog to digital (ADC) and digital to analog (DAC). ADCs and DACs can be found embedded in larger system-on-a-chip (SOC) and system-in-package (SIP) devices or stand-alone. The information on this page is focused on stand-alone data converters.

ADCs and DACs are further segmented by whether they are high speed or high precision solutions. High precision converters are now exceeding 24 bits of resolution. The majority of devices with this level of precision usually operate at a relatively low frequency, less than 2Ms/s. High speed converters, on the other hand, go as high as 16 bits of resolution and in some cases operate at greater than 500MS/s. The highest volume converters are 16 bits and below with the sweet spot at 12 bits.

The following table provides a sampling of applications and a few of their key characteristics:

Special Requirements
16 to 24 bits
44.1 to 192 kS/s
High fidelity; SNR typically > 100 dB
24 bits
< 1 kHz
Ability to resolve very small changes in capacitance, allowing easier measurement of pressure; Zero input current, programmable gain, internal temp sensor
Motor control
12 to 16 bits
2,18 Ms/s
Simultaneous sampling and 3.75 kV isolated A/D technology
10 to 14 bits
40 to 80 Ms/s
128 to 512 channels per system; low power, higher integration (quad with LVDS serial interface, octal); 110-db channel isolation
Digital camera
14 bits
Frame rate > 40Ms/s
More dynamic range allows more of the mech. camera (aperture, shutter) to be done in the digital domain
Cellular base station
14+ bits
65, 80, 105, 125, 250 Ms/s A/D, >500MHz D/As
Particular clock frequencies corresponding to specific standards

    The numbers of bits of resolution, and the sampling speed of the device, have a significant influence on the test solution required. The test requirements for data converters will typically include the following:

    Key ADC Test Requirements

      • Integral nonlinearity
      • Differential nonlinearity
      • AC tests including Signal to Noise Ratio (SNR), Spurious Free Dynamic Range (SFDR) and Total Harmonic Distortion (THD)
      • Offset
      • Gain

    Key DAC Test Requirements
      • Offset
      • Gain
      • Integral nonlinearity
      • Differential nonlinearity
      • Spurious Free Dynamic Range (SFDR)
      • Adjacent Channel Leakage Ratio (ACLR)
    For high resolution, precision data converters these tests can be extremely difficult to make, especially in a high volume production solution. You need to start with a tester designed for mixed signal testing because the noise floor and signal fidelity of the tester has a significant impact on the ability to make an accurate, repeatable and reproducible measurement. For ADC testing you need to have an extremely accurate DC source that can change levels in very small increments. For DAC testing you need an instrument capable of measuring extremely small changes in the output of the device. Of course cost of test is also a major consideration so you need to do the critical testing of converters in as fast a time as possible and preferably testing multiple devices at a time.

    Our engineers were presented with these challenges and they came up with an amazing, innovative solution for the converter test market. This instrument has no equal in the ATE industry, the Data Converter Test Module (DCTM).

    The DCTM is an X-Series based instrument with the following features:

      Best complete precision analog density in the industry
          • 16 totally independent differential channels, 4 DC sources and measures AND 4 AC sources and measures, all in one instrument! 8 can be connected to the load board at any one time.
      True 1 Part Per Million (PPM) source and 0.1 PPM measure precision
          • DC and AC sources are 1 PPM/120 dB minimum precision with excellent stability over 24+ hours
          • The “Buckable, composite” architecture affords unprecedented measure performance; ~ 140 dB!
      Laboratory, bench level performance in an ATE card allows measurements in a fraction of the time with exceptional accuracy.
          • Equivalent to 4 channels of industry standard Audio Precision AC sources and measures, 4 3458A DMM DC measure’s and 4 Krohn Hite precision DC sources
      DUT limited testing!
          • The DUT noise and throughput sets the measurement accuracy and test throughput, not the ATE
    The X-Series, with DCTM, is the leading solution for data converter testing.

    Learn more about the X-Series.

    Partner with the best. For more information, contact your nearest LTX-Credence sales representative.

    LTXC Solutions Optimized for High Throughput and Performance

    • Bench equivalent instrumentation performance for high resolution converter testing
    • Low noise floor translates to fast, accurate and repeatable measurements
    • Multi-channel precision source and measure drives high multi-site efficiency