Tektronix XYZs of Oscilloscopes

Tektronix XYZ oscilloscope

Overview

The XYZs of Oscilloscopes Primer launched by Tektronix aims to help engineers, technicians, educators, and others master the basic knowledge and operation of oscilloscopes, without the need for prior mathematical or electronic knowledge. Through theoretical explanations, chart examples, exercises, and terminology lists, it covers the entire process of oscilloscopes from principle to practice, ultimately allowing readers to describe the working principle of oscilloscopes, distinguish oscilloscope types, understand waveforms and controls, and complete basic measurements.

Signal Integrity

Core significance: The ability of oscilloscope systems to accurately reconstruct waveforms, analogous to the "imaging accuracy" and "clarity" of cameras, directly affects the time to market cycle of electronic design, product reliability, EMI compliance, and probe can also affect the signal integrity of measurement systems.

Root cause of the problem:

Speed improvement: The processor clock speed reaches 2-5GS/s, the DDR3 memory clock exceeds 2GHz, the rise time is 35ps, and the high-speed characteristics penetrate into fields such as automotive and consumer electronics, with most designs becoming "high-speed designs".

Physical limitations: The propagation time of the circuit board bus has remained unchanged for decades, and 6-inch traces become transmission lines when the signal rise time is less than 4-6ns, causing crosstalk, ground bounce, and EMI rise.

Model failure: When the signal edge velocity is 4-6 times or more the signal path delay, the lumped circuit model is no longer applicable.

Solution: Digital errors often stem from simulation problems, and it is necessary to use an oscilloscope to observe waveform details, transient signals, and correlate high-speed waveforms with data patterns.

Principle and waveform of oscilloscope (The Oscilloscope)

(1) Working principle

Oscilloscope is a graphical display device that converts electrical signals into a "time voltage" graph

X-axis (horizontal): Time

Y-axis (vertical): voltage

Z-axis (brightness): Display intensity (represented by color grading in DPO to indicate signal frequency)

(2) Waveform types and characteristics

Application scenarios of key characteristics of waveform types

Sine wave mathematical harmony, AC power supply, signal generator output basic test signal, power supply voltage

Square wave/rectangular wave square wave high and low level time are equal, rectangular wave unequal amplifier testing, timing signal (TV/computer)

Linear variation of sawtooth/triangular wave voltage (ramp) simulation oscilloscope horizontal scanning, TV grating scanning

Step/pulse step is a sudden voltage change, pulse is an "on-off" change power switch, computer data transmission (1-bit information), radar

Periodic/non periodic periodic periodic signal repetition, non periodic signal continuous change periodicity: sine wave; Non periodic: transient faults

Synchronous/asynchronous synchronous signals have a timing relationship (such as clock and data), asynchronous signals have no (such as keyboard and computer clock). Synchronization: internal signals of the computer; Asynchronous: Peripheral interaction

Complex waves combined with multiple waveform features, including amplitude/phase/frequency variation composite video signals and communication eye diagrams (such as 622Mb/s serial data)

(3) Waveform measurement indicators

Frequency and Period: Frequency (Hz)=1/Period (seconds), for example: A 3Hz sine wave has a period of 1/3 second.

Voltage: Peak to Peak Value (Vp-p, signal maximum to minimum voltage difference), Peak Value (Vp, ground to maximum voltage).

Amplitude: usually refers to the maximum voltage from ground to the signal. For example, a waveform with an amplitude of 1V has a peak to peak value of 2V.

Phase: Sine wave 1 cycle=360 °, phase difference refers to the timing difference between two similar signals, for example: current and voltage differ by 90 ° (1/4 cycle).

Automatic measurement of digital oscilloscope: including cycle, duty cycle, frequency, delay, maximum/minimum value, rise/fall time, overshoot RMS、 Shake, etc.

Types of Oscilloscopes

Type Core Architecture Key Features Applicable Scenarios

Digital Storage Oscilloscope (DSO) serial processing (amplification → ADC → storage → microprocessor → display) stores transient signals, permanently saves and processes them, without real-time brightness grading, low-speed repetition or single high-speed multi-channel design (such as capturing glitches)

Digital Fluorescence Oscilloscope (DPO) parallel processing (amplification → ADC → digital fluorescence database → direct display, microprocessor parallel processing) real-time 3D display (time, amplitude, amplitude distribution), high waveform capture rate (million level/second), general design and troubleshooting of analog oscilloscope display characteristics (video signal, communication mask testing)

Mixed domain oscilloscope (MDO) combined with RF spectrum analyzer+MSO/DPO to correlate digital, analog, and RF signal time, reducing measurement uncertainty of cross domain events. Embedded RF design (such as Zigbee radio, observing command and RF event delay)