The difference between passive probe and active probe

Passive voltage probe is the most commonly used oscilloscope probe type at present. There are no active devices such as transistors or amplifiers in passive probes, so there is no need to supply power to the probes. Therefore, the entry-level probes used by engineers for oscilloscopes are usually passive probes. Passive probes are made of wires and connectors. When compensation or attenuation is required, resistors and capacitors are also included. There are no active devices (product tubes or amplifiers) in the probes, there is therefore no need to supply power to the probe. Various digital oscilloscopes are used to measure the amount of related electrical signals. There are many types of probes matched with these oscilloscopes, including passive probes (including high-voltage probes and transmission line probes), active probes (including active single-ended probes, active differential probes, etc.), current probes, optical probes, etc.

Each probe has its advantages and disadvantages, and thus each has its applicable occasions.

1) Active probe

(1) the advantages of active probe

Because of its high bandwidth, small input capacitance, small ground loop and other advantages, it is widely used in the field of high-speed digital measurement.

(2) Insufficient active probes

Active probe price is high, the dynamic range is small, electrostatic sensitive, calibration trouble

2) Passive probe

The entry-level probes that every engineer uses an oscilloscope are usually passive probes. Passive probes are made of wires and connectors, and when compensation or attenuation is required, resistors and capacitors are also included. There are no active devices (transistors or amplifiers) in the probe, so no

It is necessary to supply power to the probe.

(1) Passive probe advantages:

They are not only easy to use, but also widely used.

Large voltage dynamic range, strong physical and electrical performance, suitable for browsing design

(2) The passive probe is insufficient, the capacitance load is large, there is not enough bandwidth, the ground wire is affected, the probe is not sharp enough (and easy to damage), and it is difficult to connect the surface mount device. The active probe can be single-ended voltage, differential voltage, or current. The power supply mode includes oscilloscope direct power supply or external power supply, or battery power supply. Specific needs according to different applications to choose. Passive probes are more durable and less expensive. Because of its high bandwidth, small input capacitance, small ground loop and other advantages, it is widely used in the field of high-speed digital measurement. They have a very bright dynamic range. Typical 10:1 probes have a dynamic range of> 30 V and a high input bright reactance that can be matched to the input bright reactance of the oscilloscope. However, compared with the active probe or the low-light (20) electro-positive device, the high-light anti-input probe will produce a larger capacitive load and have a narrower bandwidth.