Transient and overvoltage recovery testing of analog-to-digital converters

The dynamic performance (the noise effective number of bits, the spurious-free dynamic range, and the signal-to-noise ratio) of the high-speed analog-to-digital (A/D) converters used in radar systems can be characterized by a spectral analysis test consisting of a series of sinusoidal signals of different frequencies and amplitudes. Some radar systems are exposed to large noise impulses either from an environment or hostile electronic countermeasures (ECM). For these systems, in order to minimize system impact, the radar specification requires that the converters meet transient and overvoltage recovery specifications. In order to verify these requirements, we developed a test method which is a variant of the standard sine-wave test. The transient and overvoltage recovery performance of the converters is determined by applying a poised waveform and determining the time required to recover from the pulse. We designed and built a special test fixture that produces a pulse that is clean to 12-bits accuracy with a 400-ohm load. This paper describes the characteristics of two different 12-bit, 4-MHz converters that were tested, the test equipment, the data analysis, and the transient and overvoltage recovery test results