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Q1 gw_product_detail_bar.png gw_product_detail_bar.png Oscilloscope Probes – Types of Probes

Common types of oscilloscope probes can be roughly divided into the following types according to their characteristics:


Voltage probe:

  • Passive voltage probe (10:1 or 10:1/1:1 switchable, standard configuration probes usually have these two magnifications). Other passive high-voltage probes can provide larger attenuation magnifications
  • 450 ohm Zo probe for 10:1 attenuation of 50 ohm system instruments
  • Active high voltage differential probe
  • Active high frequency single-ended/differential probes


Current probe

  • Passive current probe (can only measure AC current)
  • Active current probe (energy measurement of DC and AC current)



  • Logic probes (for logic analyzers or mixed-signal oscilloscopes)
  • Optical/electrical conversion probe
  • Other converters (any signal that can convert a physical quantity into a voltage can be measured with an oscilloscope)


More Porduct information: Oscilloscopes


Q2 gw_product_detail_bar.png gw_product_detail_bar.png The impact of long memory oscilloscopes on signal acquisition

In the previous article [Introduction to Oscilloscope Types], the data processing methods of different oscilloscopes were mentioned. It was mentioned that ARO directly outputs the signal to the screen without digital A/D processing, so what you see is what you get. DSO requires CPU processing time to output the signal to the screen. This article mainly allows users to understand the impact of memory size on signal acquisition with a digital oscilloscope (DSO).


Memory=Sample rate*Time


Two application advantages of digital oscilloscope long memory can be seen from the above formula.

  1. Fixed time and long memory can maintain a good sampling rate at medium and low speed time base range.
  2. Fixed sampling rate and long memory can capture longer transient signal time


Another advantage of long memory is its application in FFT, which can reduce noise (Noise Floor) and improve frequency resolution.


It seems that long memory has many advantages. Are there any disadvantages to long memory?


Yes, long memory will require longer computing time to process data, so it will affect the waveform update rate.


More Porduct information: Oscilloscopes



Q3 gw_product_detail_bar.png gw_product_detail_bar.png The difference between active probes and passive probes


A comparison of active probes and passive probes is as follows:


Category/comparison item Active probe Passive probe
Measurement dynamic range
  • High voltage active probes are higher than passive probes
  • High frequency active probes are lower than passive probes
  • Lower than high voltage active probes
  • Higher than high frequency active probes
Bandwidth The current bandwidth in the industry can reach 30GHz Except for the 45 ohm Zo probe, most only reach 500MHz
Capacitive load effect Low capacitance value, small load effect on rise time when observing high-speed signals High capacitance value, when observing high-speed signals, the load effect on the rise time is large
Resistive load effect Due to the low input impedance, it is easy to have a high resistive load effect on High Z circuits The input impedance when paired with an oscilloscope is 10M ohms, and the resistive load effect is low at low frequencies
Inductive load effect
  • High-voltage active probes require the test leads to be twisted to reduce inductive load effects
  • The high-frequency active probe has a short ground wire, and the inductive load effect of ringing at the front edge of the square wave is low
  • Lower than high voltage active probes
  • Higher than high frequency active probes
Price Expensive Inexpensive


More Porduct information: Oscilloscopes


Q4 gw_product_detail_bar.png gw_product_detail_bar.png Definition of Oscilloscope Bandwidth

Bandwidth determines the basic ability of the oscilloscope to measure signals. As the signal frequency increases, the oscilloscope's ability to accurately display the signal decreases. Through this specification, users can confirm the frequency range that the oscilloscope can accurately measure.


The definition of oscilloscope bandwidth is the frequency at which the sinusoidal input signal is attenuated to 70. 7% of the true amplitude of the signal, which is called the -3 dB point (half power point), based on the logarithmic scale.


More Porduct information: Oscilloscopes

Q5 gw_product_detail_bar.png gw_product_detail_bar.png How often do I need to calibrate my oscilloscope?

The recommended calibration period for all oscilloscopes is 12 months, but users can evaluate the test environment and required accuracy to determine whether the standard calibration period meets your specific needs.




The calibration of the instrument is to confirm the specifications and make adjustments.


General secondary laboratories can only confirm specifications. When the instrument being calibrated does not meet the factory specifications, it can only state on the test report that it exceeds the specifications. The current instruments have already entered the digital age, and many specifications and parameters can be adjusted to return to the factory specifications for new instruments, and only the instrument manufacturer's secondary laboratory has the adjustment steps and procedures.


Therefore, the manufacturer's calibration cost will be higher. Once there is a scenario of exceeding specifications, incoming and outgoing reports will be provided. If the instrument cannot be restored to the factory specifications through adjustments, it will need to be repaired as soon as possible depending on the situation.


GW Instek Calibration Laboratory Tel: +886 2 2268 0389 ext 308


The calibration that the user needs to perform by themselves include:


  1. Low-frequency compensation and calibration of passive probes to avoid errors in amplitude measurement
  2. Vertical offset calibration uses signal path compensation (SPC) to eliminate vertical offset errors. This error will affect DC measurement and conduction loss of the power circuit.


More Porduct information: Oscilloscopes





Q6 gw_product_detail_bar.png gw_product_detail_bar.png How to choose the right oscilloscope?

The oscilloscope has been one of the most important and common electronic test instruments from its development to its introduction to the market. Due to technological advancements, oscilloscope capabilities have continuously improved, and their performance and prices vary widely, ranging from a few thousand dollars to several million dollars. Choosing the right oscilloscope becomes a knowledge.


  1. Choose from the application aspect: signal verification in the laboratory (the oscilloscope bandwidth is 5 to 10 times the signal to be tested). A typical application example: USB physical verification. Design verification for R&D (the oscilloscope bandwidth is 5 to 10 times the signal to be tested.) Although what you see at 1 to 3 times may be a distorted waveform, it is an economical choice for maintenance applications where you can make judgments about whether there is a signal or not.
  2. The maximum sampling rate should be more than twice the bandwidth of the oscilloscope. Based on the oscilloscope's 5 times bandwidth rule, taking a 100MHz oscilloscope as an example, the amplitude error of the 20MHz sine wave is less than 3%. For a 20MHz square wave, users can barely see the attenuated third harmonic (60MHz). For the square wave frequency is higher than 20MHz, users can only observe an attenuated sine wave on a 100MHz oscilloscope. To observe a 20MHz signal, a sampling rate of (100MHz*2=200MS/s) 200M is more than enough.
  3. The memory 10 times larger than the fastest required transient signal multiplied by the longest transient time.
  4. Be aware of whether the memory of FFT exceeds 1M.
  5. A waveform update rate exceeding 10,000 times per second is generally sufficient to avoid missing too many signal details.


More Porduct information: Oscilloscopes



Q7 gw_product_detail_bar.png gw_product_detail_bar.png What is an oscilloscope?

"Oscilloscope" is a combination of two words:


  1. Oscillo (abbreviation for oscillation)
  2. Scope (observation) 


The main function:

  1. An instrument that displays the relationship between signal time (seconds) and amplitude (voltage). As long as the physical quantity (light, current, pressure, etc.) can be converted into a voltage signal through a probe or converter, it can be observed by the oscilloscope. An oscilloscope is a type of time domain measurement instrument.
  2. Electronic signals are invisible light. The invisible light needs to be converted into visible light through an oscilloscope before engineers can observe the signal. The oscilloscope is the eyes for electronic engineers to observe signals.


What you need to know when using a digital oscilloscope

  1. Sampling principle and technology: A sine wave requires more than two points to restore (theoretical value). The reference principles for practical application are: sine wave (sampling rate is 5 times greater than the signal frequency), square wave (sampling rate is 10 times greater than the signal frequency). Sampling technology includes equivalent time sampling and real-time sampling.
  2. The relationship between sampling rate and memory: Memory=Sample rate*Time
  3. The relationship between waveform update rate and memory: The waveform update rate is inversely proportional to the memory. The highest waveform update rate specification is defined under short memory.


 More Porduct information: Oscilloscopes


Q8 gw_product_detail_bar.png gw_product_detail_bar.png GW Instek Oscilloscopes Rack Mount Kit

GRA-411 Rack Mount Kit for GDS-3000 series

GRA-420 Rack Mount Kit for GDS-2000A series

GRA-426 Rack Mount Kit for MDO-2000A series, MDO-2000E series, MSO-2000E series, GDS-2000E series, GDS-1000B series

GRA-443 Rack Mount Kit for GDS-3000A series


Q9 gw_product_detail_bar.png gw_product_detail_bar.png May I use GDS-2000A’s logic analyzer probe to MSO-2000E?

The logic analyzer probe is not universal. Only probe clips are allow to share.

Q10 gw_product_detail_bar.png gw_product_detail_bar.png What is the main difference between MDO-2000A and MDO-2000E series?

Please see below table

  MDO-2000A MDO-2000E
Bandwidth 300M/200M/100MHz 200M/100M/70MHz
Sampling rate 2GSa/s interleaved 1GSa/s interleaved
Memory depth 20M/CH 10M/CH
Channel 2 2 or 4
25MHz Function generator Only on MDO-2000AG model Yes
Q11 gw_product_detail_bar.png gw_product_detail_bar.png What is the main difference between GDS-1000B and GDS-2000E series?

GDS-2000E provided bus decode function; segment memory; waveform search function which not on the GDS-1000B.
For the sampling rate comparison, both series are max. 1GSa/s.For GDS-2000E series ,the max. sampling rate will keep 500MSa/s for 4CH activate and 2CH activate will keep 1GSa/s. However, for GDS-1000B series, the max. sampling rate will reduced to 250MSa/s for 4CH activate and 2CH activate will reduced t0 500MSa/s.

Q12 gw_product_detail_bar.png gw_product_detail_bar.png Why the input square waveform is looks like sine waveform in the oscilloscope.

When the rise time or fall time of square signal is close to the period, the display waveform will looks like sine waveform.
For example, to test 25MHz square waveform.
The rise time is 0.35/25MHz=0.014us. The period is 1/25MHz=0.04us.
Since the rise time is close to the period ,the output waveform will looks like sine waveform.