# University Project Help

#### yaya

Joined Mar 27, 2005
3
I need some major help, much would be appreciated if anyone could offer any help. hell i would even supply a reward or something.

I have achieved Vg=3.9Volts
Idss=.5mA
ID=1.6mA
Vgs=2.89Volts
and Av=voltage gain=-2.68
The output impedence i am not sure how to do exactly.
I have calculated these values but PSpice offers a couple different values. Was wondering if anyone got these values or if not how you got them.

Consider the AC-coupled amplifier shown below. All capacitors are 10µF. The
MOSFET has the following parameters: KnW/L = 1E-3 A/V2, Vt = 1 V

2. Calculate the DC-bias point (also called Q-point)

4. Calculate the small-signal gain of the amplifier stage
5. Calculate the input and output impedance of the amplifier in the midband
6. Calculate the small-signal gain of the amplifier with capacitor C3 removed.

Thank you for ANY help!
circuit attached
[attachmentid=517]

#### hgmjr

Joined Jan 28, 2005
9,029
Originally posted by yaya@Mar 27 2005, 07:21 PM
have a project in my microelectronics class. I want to understand how to find some things out about this particular circuit.
1. I need to find the DC bias point, Q point.
I cannot find out how to do input impedence or output impedence yet, although i am working on it.
i know formulas for Vgs and Id however i do not think they apply to this particular circuit. any help would be greatly appreciated.

circuit attached
[attachmentid=517]
[post=6460]Quoted post[/post]​
{Post = UG}
Due to the wide variation of parameters associated with MOSFET devices, the device part number for the MOSFET being used in your circuit will be needed to make an accurate calculation of the DC bias point.

Can you post the MOSFET part number?

#### fobishduck

Joined Apr 5, 2005
2
i suggest you also define the desired performance parameter, including up to what frequency this is to operate at... i suppose you are looking at at least 100MHz, since it's microelectronic class...

given some more information about what you want to do exactly, i'm sure people here will help out.

#### mozikluv

Joined Jan 22, 2004
1,437
hi

here's my contribution for the moment. the cap impedance of your input coupling cap should be lower than the input resistance looking into the gate so that your input cap will act as a short circuit to your sinusoidal signal.

#### mozikluv

Joined Jan 22, 2004
1,437
hi