how to increase gm OP voltage gain

[pianomania]

increase gm

we all know two stages OP AC gain= gm x ro
but if we design a one stage OP which only has gm,
how do we get the AC Voltage gain ?
and how to increase the gain?

 

[LvW]

....but if we design a one stage OP which only has gm...

gm is the property of a transistor - not a property of an opamp, is it ?
If a circuitry with a differential input "has only gm" I think it is something like an OTA.
You should be a bit more detailed.

 

[pixel]

we all know two stages OP AC gain= gm x ro
but if we design a one stage OP which only has gm,
how do we get the AC Voltage gain ?
and how to increase the gain?

If you have only gm than there is no voltage gain...
gm unit is A/V


Your mosfet has ro, no matter if there was one or two stage amplifier.

 

[cheney_pm801]

If the ro of the op is infinite, the AC gain is determined by ri of next stage. So the gain is gm*ri

 

[edge_tv]

The Gain of a singel stage is Gain=gm*R1 with R1 is the Output resistens of the single Stage, if you have only one Transistor with a curren sourc as load Gain is G=gm*ro with ro is resistens of the Transistor.
Singel Stage
Normaly you have somthing like a Common source Configuration, so your Output resistens is R1=r0_input*r0_load/(r0_input+r0_load), you can boost your gain with cascod
need more Gain: Gain Boosting

 

[tonyshao]

You should think about sacrificing some other charactristic to meet your voltage gain. What do you want to sacrifice according to your aplication?