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Design >> Analog Design >> about the active load resistance.
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Message started by Robert on Jun 6^th, 2005, 12:08am

Title: about the active load resistance.
Post by Robert on Jun 6^th, 2005, 12:08am

hi,guys
i am a new analog boy.now i am puzzled that the equivalent resistance of active load is ron or 1/gm on the op list. hope somebody can reply this topic,thanks in advance.

Title: Re: about the active load resistance.
Post by sheldon on Jun 6^th, 2005, 8:21am

Robert,

Could you provide some additional information, for
example, what is the Vdsat and the Vds of the device?
In general, the rout of a transistor is a dependent on
its region of operation. If Vds<Vdsat, then the device
is in the linear region and rout is a low number, i.e.,
not much gain. If Vds>Vdsat, then the device is in
saturation and rout is a little bigger number, i.e.,
there is a little more gain. If the goal is to use the
device as an active load, then it should be operated
in the sauration region. Typically, switches operate
in the linear region.

Best Regards,

Sheldon