Review Suggested Edit

You can't approve or reject suggested edits because you haven't yet earned the Edit Posts ability.

Using FET based followers and design rules

~~Usually, voltage followers are built with with bipolar transistors (or with oamps if better precision is needed).~~
In this case, the simple rule says that the transistor emitter "follows" the input voltage one diode drop below, a somewhat approximate but understandable term.
![bip-follower](https://electrical.codidact.com/uploads/wPu9Zu39CsByWrS5c3Z6PNXg)
It is perhaps less usual to see field effect based followers, and I'm particularly interested in jfets and mosfets.
![mos-follower](https://electrical.codidact.com/uploads/DAm3X86poSg4o1tPCnYks5NG)
~~From my readings about this topic, it is still unclear to me how to determine the voltage drop introduced by theses transistors (parallel to the diode drop for the bipolar transistor follower).~~
~~Also, if there is a way to control this drop (without using an oamp), what are the design rules, or perhaps the rules of thumbs ?~~

Usually, voltage followers are built with bipolar transistors (or with opamps if better precision is needed).
In this case, the simple rule says that the transistor emitter "follows" the input voltage one diode drop below, a somewhat approximate but understandable term.
![bip-follower](https://electrical.codidact.com/uploads/wPu9Zu39CsByWrS5c3Z6PNXg)
It is perhaps less usual to see field effect based followers, and I'm particularly interested in jfets and mosfets.
![mos-follower](https://electrical.codidact.com/uploads/DAm3X86poSg4o1tPCnYks5NG)
From my readings about this topic, it is still unclear to me how to determine the voltage drop introduced by these transistors (parallel to the diode drop for the bipolar transistor follower).
Also, if there is a way to control this drop (without using an opamp), what are the design rules, or perhaps the rules of thumbs ?

transistor follower field-effect-transistor