New components have made 18-bit DACs a practical design alternative. This application note describes a measurement technique for 18-bit DAC settling time, which is the time required for the DAC output to settle to within 4ppm of the command code.
Performance requirements for precision applications are increasingly demanding, pushing beyond the capabilities of standard 16-bit digital-to-analog converters (DACs). New 18-bit monolithic DAC components offer a practical alternative at lower costs. However, measuring the settling time of these devices to 18-bit resolution is extremely difficult due to the small error bands involved.
The document introduces a novel measurement technique capable of achieving 20-bit (1ppm) resolution for times as short as 265ns. This method utilizes sampling techniques and an external wideband preamplifier to overcome oscilloscope overdrive issues, allowing for accurate observation of settling waveforms without damaging the instrument.
The developed method provides a 20-bit (1ppm) resolution.
It is usually specified for a full-scale 10V transition.
The Schottky diodes have a 400mV drop.