T. M. Souders

Cutting the high cost of testing

A modeling approach to the overly long testing of analog and mixed-signal devices that saves substantially on time and cost is described. The discussion focuses on the particular case of a 13 bit analog-to-digital converter (ADC). The problems that arise in testing ADCs are identified, showing that the success of the test method depends critically on the quality of the model. Two types of models are examined, physical-sensitivity-based models and empirical-learning-based models, and it is noted that the latter are especially attractive for performance-testing applications like the ADC example. An 18-parameter model of the 13 bit ADC was developed using a combination of physical and empirical modeling techniques and was highly successful. With an array process to speed up the computations, the computational overhead can be kept below 1 s per device, so the test time, which is reduced by a factor of 128, becomes negligible.<<ETX>>

Developing linear error models for analog devices

Techniques are presented for developing linear error models for analog and mixed-signal devices. A simulation program developed to understand the modeling process is described, and results of simulations are presented. Methods for optimizing the size of empirical error models based on simulated error analyses are included. Once established, the models can be used in a comprehensive approach for optimizing the testing of the devices. Models are developed using data from a group of 13-b analog-to-digital converters and are compared with the simulation results. >

LINEAR ERROR MODELING OF ANALOG AND MIXED-SIGNAL DEVICES

Techniquesare presented for developinglinear error models for analog and mixed-signal devices. Methods for choosingparameters and assuring the models are complete and wellconditioned, are included. Once established, the models can be used in a comprehensive approach for optimizing the testing of the subject devices.

A fast pulse oscilloscope calibration system

A system is described for calibrating high-bandwidth oscilloscopes using pulse signals. The fast-pulse oscilloscope calibration system (FPOCS) is to be used to determine the step response parameters for digitizing oscilloscopes having bandwidths of /spl sim/20 GHz. The system can provide measurement traceability to standards maintained at the U.S. National Institute of Standards and Technology (NIST). It comprises fast electrical step generation hardware, a personal computer (PC) and software, and a reference waveform, i.e., a data file containing an estimate of the step generator output signal. The reference waveform is produced by prior measurement by NIST of the step generator output signal (calibration step signal). When the FPOCS is in use, the calibration step signal is applied to the device under test, which is an oscilloscope sampling channel. The measured step waveform is corrected for timebase errors, then the reference waveform is deconvolved from it. The results are impulse, step, and frequency response estimates, and their associated parameters (e.g., transition duration, transition amplitude, -3 dB bandwidth) and uncertainties. The system and its components are described, and preliminary test results are presented.

NIST-NPL interlaboratory pulse measurement comparison

A comparison of the pulse parameter values obtained from the pulse measurement services of the National Institute of Standards and Technology, USA, and the National Physical Laboratory, U.K., was performed. The comparison was based on the pulse parameters of amplitude, transition duration, overshoot, and undershoot (preshoot). The parameter comparison was applied to raw (measured) waveforms, corrected waveforms (if applicable), and reconstructed waveforms. The results of the comparison show that the pulse parameter values for both national laboratories are within published uncertainties.