Circuit allowing trigger sensitivity of digital oscilloscope to be continuously adjustable

Abstract

The invention provides a circuit allowing trigger sensitivity of a digital oscilloscope to be continuously adjustable. The circuit is composed of a buffer isolation amplifier, a digital analog converter, an analog comparator, a digital rheostat, a CPU controller and a resistance network. By means of the scheme, the circuit has the advantages that through the digital rheostat, trigger sensitivity can be continuously adjustable, adjustment stepping is small, the resolution ratio is high, resistance tolerance is small, accuracy is high, control is flexible, and use is convenient; when high-frequency noise is superposed in signals, a user can obtain stable trigger waveforms only by reducing the value of the digital rheostat in a numerical control mode through a 12 C bus.

Description

technical field [0001] The invention belongs to the technical field of continuously adjustable sensitivity, and in particular relates to a circuit with continuously adjustable trigger sensitivity of a digital oscilloscope. Background technique [0002] A digital oscilloscope can not only stably display repetitive periodic signals, but also display signals with specific characteristics. Its trigger sensitivity directly determines its ability to capture and display weak signals. Most of the existing trigger systems of digital oscilloscopes are analog trigger systems, and the comparators responsible for detecting signal levels use analog comparators that process the original measurement signals. There are two conflicting requirements for the trigger sensitivity of an analog comparator. Stable triggering of noise signals requires the trigger system to achieve a certain hysteresis around the trigger threshold, so the analog comparator must be compensated by feedback technology t...

AI Technical Summary

Problems solved by technology

[0004] The feedback resistor Rh of the analog comparator of the existing analog trigger system cannot be continuously adjusted. If the value of Rh is too large, when high-frequency noise is superimposed in the signal, the digital oscilloscope will not be able to obtain a stable trigger waveform; Small, when a small amplitude signal is input, the feedback resistor Rh will increase the hysteresis effect of the system, reduce the sensitivity of the trigger system, and cause the small amplitude signal to be unable to trigger the display stably

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