Shenzhen Winna Electronic Industrial Co., Ltd.

An oscilloscope is an electronic measuring instrument that can convert electrical signals into visual waveforms and is widely used in fields such as electronic engineering, scientific research, and teaching. By displaying the relationship between the voltage of a signal and time, it helps engineers and researchers analyze the characteristics of signals, detect faults, or verify circuit performance. The following is a detailed introduction from aspects such as principle, structure, function, and application:

I. The Core Principle of the Oscilloscope

The oscilloscope is based on an electronic oscilloscope tube (in the early days) or digital sampling technology (modern), presenting the time-domain characteristics of electrical signals in a graphical manner. Its core principle can be summarized as follows:

Signal Conversion: The input voltage signal (or non-electrical signals such as current and temperature converted through probes) is converted into the deflection of an electron beam or digital sampling points.

Time-domain Display: On the display screen, the horizontal axis (X-axis) represents time, and the vertical axis (Y-axis) represents the voltage amplitude, thus forming a waveform curve.

II. The Main Structure and Components of the Oscilloscope

Analog Oscilloscope (Traditional Type)

Oscilloscope Tube: It contains an electron gun (emitting an electron beam), deflection plates (X-axis and Y-axis deflection control), and a fluorescent screen (which emits light to display the waveform after being bombarded by the electron beam).

Vertical System (Y-axis): Amplifies or attenuates the input signal and adjusts the vertical sensitivity (such as 1V/div).

Horizontal System (X-axis): Controls the sweep rate (such as 1ms/div) and generates a time base.

Trigger System: Stably displays repetitive waveforms. By setting trigger conditions (such as voltage threshold, slope), the waveform starts to sweep at a fixed position.

Digital Oscilloscope (Modern Mainstream)

Signal Conditioning Circuit: Amplifies, attenuates, and filters the input signal to adapt to the sampling range of the ADC (Analog-to-Digital Converter).

ADC Sampling Module: Converts the analog signal into a digital signal. The sampling rate (such as 1GS/s) determines the time accuracy of the waveform.

Memory: Stores the digitized waveform data. The storage depth (such as 1Mpts) affects the ability to record long-time waveforms.

Processor and Display Screen: Processes data through a CPU or FPGA, reconstructs the waveform on an LCD/LED screen, and supports digital functions such as zooming, measurement, and FFT.

III. The Key Functions and Measurement Parameters of the Oscilloscope

Basic Measurement Functions

Waveform Display: Intuitively presents the shape, amplitude, and period of signals such as sine waves, square waves, and pulse waves.

Parameter Measurement: Automatically calculates parameters such as peak-to-peak voltage, effective value, frequency, rise time, and duty cycle.

Trigger Function: Stably displays complex or non-periodic waveforms and supports trigger modes such as edge trigger, pulse width trigger, and video trigger.

Advanced Functions (Unique to Digital Oscilloscopes)

FFT (Fast Fourier Transform): Converts the time-domain waveform into a spectrum diagram to analyze the frequency components of the signal (such as frequency-domain interference analysis in EMC).

Waveform Storage and Playback: Saves historical waveforms for comparative analysis or captures occasional abnormal signals (such as glitches, transient interferences).

Protocol Analysis: Supports the decoding of bus protocols such as I2C, SPI, and CAN, and displays the logic levels and timing relationships of digital signals.

Key Technical Parameters

Bandwidth: The highest frequency that the oscilloscope can accurately measure (for example, a 100MHz bandwidth means that the attenuation of a 100MHz sine wave is ≤3dB), determining the restoration ability of high-frequency signals.

Sampling Rate: The number of samples per second, at least 2 times the highest frequency of the signal (Nyquist sampling theorem), and it is recommended to reach 5 - 10 times to avoid aliasing.

Vertical Resolution: The number of bits of the ADC (such as 8-bit, 10-bit, 12-bit), determining the accuracy of voltage measurement (the higher the number of bits, the smaller the quantization error).

IV. Typical Application Scenarios of the Oscilloscope

Electronic Circuit Design and Debugging

Detect Signal Integrity: Observe phenomena such as reflection, crosstalk, and ringing of high-speed digital signals, and optimize PCB wiring (such as impedance matching).

Analyze Analog Circuits: Measure the gain and distortion of amplifiers, the ripple voltage of power supplies, the output signals of sensors, etc.

Power Electronics and Energy Field

Measure the PWM waveforms of inverters and switching power supplies, and analyze the switching losses and voltage spikes of switching tubes.

Monitor the motor drive signals and diagnose startup abnormalities or overload faults.

Communication and RF Field

Analyze the modulation waveforms of RF signals (such as ASK, FSK, QAM), and optimize antenna matching in conjunction with a vector network analyzer.

Debug the timing and level compatibility of communication interfaces (such as USB, HDMI).

Scientific Research and Education

Observe the propagation characteristics of sound waves and electromagnetic waves in physics experiments, and measure nerve electrical signals and electrocardiograms in the biomedical field.

In teaching scenarios, intuitively display signal principles to help students understand basic concepts of the time domain and frequency domain.

V. Types of Oscilloscopes and Selection Suggestions

Classification by Type

Handheld Oscilloscope: Portable, suitable for on-site maintenance (such as automotive circuit detection), with a bandwidth generally ≤100MHz.

Benchtop Oscilloscope: Comprehensive in function, with a bandwidth ranging from 50MHz to 10GHz (high-end models), suitable for precise measurements in the laboratory.

Mixed Signal Oscilloscope (MSO): Integrates digital channels (such as 16-channel logic analysis), and simultaneously observes the timing of analog signals and digital buses.

Key Selection Factors

Bandwidth: Select according to the highest frequency of the measured signal (for example, when measuring a 10MHz square wave, it is recommended that the bandwidth be ≥50MHz).

Sampling Rate: At least 2 times the bandwidth (for example, a 100MHz bandwidth corresponds to a 200MS/s sampling rate).

Functional Requirements: Whether functions such as FFT, protocol analysis, and long storage depth are required (for example, EMC testing requires a high sampling rate + FFT function).

Summary

As the "eyes of electronic engineers", the oscilloscope provides a fundamental and crucial tool for circuit design, fault diagnosis, and signal analysis by visualizing the time-domain characteristics of electrical signals. The technological evolution from analog to digital enables it not only to display waveforms intuitively but also to meet the measurement requirements of modern high-frequency and complex signals through digital processing and analysis functions.