Evaluating 8-bit Oscilloscopes
Publication Number: 5991-1617EN
Publication Date: 2017.12.01
Language: English
Application Notes

Evaluating 8-bit Oscilloscopes

Show Description

 

How Does an Oscilloscope's ADC Impact Vertical Resolution?

 

All manufacturers specify the number of ADC bits in their oscilloscopes, and resolution is the smallest quantization level determined by the analog-to-digital (A/D) converter in the oscilloscope. 

 

The number of unique digital codes or quantization levels (Q levels) is 2n where n is the number of ADC bits. An 8-bit ADC has 256 Q levels, whereas a 12-bit ADC has 4096 Q levels. Each oscilloscope ADC operates on the oscilloscope’s full scale vertical value. Thus the Q-level steps are associated with the full-scale vertical oscilloscope setting. If the user adjusts the vertical setting to 100 mV per division, for example, full screen equals 800 mV (8 divisions * 100 mV/div) and Q-level resolution is equal to 3.125 mV/level (800 mV divided by 256 levels). If measuring current, for a vertical setting of 10 mA/div, Q-level resolution is set at 312.5 µA/level (80 mA divided by 256 levels)