I saw a circuit that uses two NMOS MOSFETs as a voltage divider, and I was just wondering why that would be used instead of just using a normal resisitive divider? A screenshot of the CMOS circuit is attached.
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Hi, yes the FETS have lengths and widths that are different, it is designed in such a way that it gives an output of 1V. It is just a standalone circuit, it was not anywhere. I was just wondering what are the advantages over a resistive divider/Are those two NFETs the same dimensions? If so, it seems odd that the voltage at the junction isn't the midpoint of the power supply since both transistors are diode-connected and the junction is the Vgs of the bottom transistor above ground and the Vgs of the top transistor below the rail and both transistors are carrying the same current.
Do they have different widths and lengths and that just isn't being shown?
What kind of circuit was this for that you saw this on? Was it an integrated circuit? If so, it's likely that it was a bias voltage generator in which the top transistor is setting a current in the both transistor and the bottom transistor is one said of a current mirror. One of the beautiful things about integrated CMOS circuits is that you can then duplicate that current in literally millions of other transistors throughout the chip.
Are you sure it wasn't meant to be used on an IC? I've never seen discrete MOSFETs where the user had the ability to control the widths and lengths.Hi, yes the FETS have lengths and widths that are different, it is designed in such a way that it gives an output of 1V. It is just a standalone circuit, it was not anywhere. I was just wondering what are the advantages over a resistive divider/
That's one of the reasons I suspect that the circuit is for an IC (fabricated on a CMOS process).Just a small point of fact only for information purposes.
Two NMOS configured as such is not technically considered "CMOS" where one of the two would be PMOS.
It would only make sense on an integrated circuit where resistors would take more die area.I saw a circuit that uses two NMOS MOSFETs as a voltage divider, and I was just wondering why that would be used instead of just using a normal resisitive divider?
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