What does it mean when transistors are matched?

What does it mean when transistors are matched?

Matched means the transistors were selected from a pile by measuring them to find the two that “match” closest for a particular variable, presumably the one you care about. However, you can never achieve identical in all parameters.

Why transistors used in circuit?

A transistor amplifies current and can be used as a switch. This arrangement where the emitter (E) is in the controlling circuit (base current) and in the controlled circuit (collector current) is called common emitter mode. It is the most widely used arrangement for transistors so it is the one to learn first.

How does JFET transistor match?

Measuring JFETs

1. Get a 5 to 13 volt supply and a DC voltmeter (we used 12V)
2. Connect the +V to the Drain.
3. Connect the Gate and Source together to a 100Ω resistor.
4. Connect the other lead of the resistor to ground.
5. Measure the voltage across the resistor, which gives the Idss (1 volt = 10 mA of current)

Why do you need to match two transistors?

The idea is to find two transistors whose base–emitter voltage or Vbe is within a couple of millivolts of each other, under a constant current. There are other applications where this type of matching is needed.

When to use VBE instead of transistor matching?

Transistor matching is required in several situations. One is in selecting matched pairs for exponential or logarithmic circuits. Here it is actually the leakage currents that should be matched, but these are difficult to measure without special equipment, so Vbe is often used instead.

Can a multi meter be used to test transistors?

Multi-Meters use battery power which at critical junctures tend to get exhausted, hampering the testing procedure. This simple circuit can be used for testing and matching transistors in mass production chains, without any hiccups or issues.

Why is it important to match transistors in a VCO?

The more accurate the match, the better tuning of the voltage controlled oscillator across a larger range. It will also make the setting up of the VCO easier. If the transistors are badly matched you may struggle to get any form of consistency when it comes to trying to calibrate them.