Home > Community > Forums > Cadence Academic Network > Why 2nd Stage of Multi Stage Common Source Amplifier Resulting in Attenuation of Signal?

Email

* Required Fields

Recipients email * (separate multiple addresses with commas)

Your name *

Your email *

Message *

Contact Us

* Required Fields
First Name *

Last Name *

Email *

Company / Institution *

Comments: *

 Why 2nd Stage of Multi Stage Common Source Amplifier Resulting in Attenuation of Signal? 

Last post Mon, Dec 3 2012 3:21 AM by oldmouldy. 1 replies.
Started by Shiraz 02 Dec 2012 08:08 AM. Topic has 1 replies and 925 views
Page 1 of 1 (2 items)
Sort Posts:
  • Sun, Dec 2 2012 8:08 AM

    • Shiraz
    • Not Ranked
    • Joined on Sun, Sep 23 2012
    • Posts 15
    • Points 195
    Why 2nd Stage of Multi Stage Common Source Amplifier Resulting in Attenuation of Signal? Reply

     Dear all,

    Sorry but I thought I would follow the one question per post rule (so reposting with focused question):

    How do I get signal amplification with a multistage common source amplifier with active load ?

    I have a working version of a common source amplifier with an active load (a drain current of 50 uA) going into the drain (here : https://docs.google.com/open?id=0BwG45lg3wcwnU3ZDQ3NtNjZCM2s   the file is titled: Project_Working with 1000 Gain-Nov-30-2012.zip is a file that has the original circuit which gives an input signal of 1mv an amplification of 1000 (to around 1V).)

     

    All I did was add another stage to this amplifier as listed in countless examples of multi  stage common source amplifiers throughout every book (and online like here : http://ocw.mit.edu/courses/electrical-engineering-and-computer-science/6-012-microelectronic-devices-and-circuits-fall-2005/lecture-notes/lecture21annotat.pdf ). The second stage has the exact same specs as the first stage so I should get multiplication of gain or double the gain right ?

    Apparently I don't because instead I see an attenuation of signal (here is this new project:  https://docs.google.com/open?id=0BwG45lg3wcwnNWRXUlV6RVdkNU0  ) Why is this attenuation happening or rather how do I get the predicted gain of stage 1 gain x stage 2 gain ?

    • Post Points: 20
  • Mon, Dec 3 2012 3:21 AM

    • oldmouldy
    • Top 10 Contributor
    • Joined on Tue, Jul 15 2008
    • Woking, Surrey
    • Posts 1,440
    • Points 24,520
    Re: Why 2nd Stage of Multi Stage Common Source Amplifier Resulting in Attenuation of Signal? Reply

    Well, N2 has a Vgs of 12V, that going to be pretty certainly saturated and not allow much action at the drain.

    Also, if you did get this "anything like" working, 1mV * 1000 * 1000 is going to be greater than your 12V supply so something is going to have to give!

    • Post Points: 5
Page 1 of 1 (2 items)
Sort Posts:
Started by Shiraz at 02 Dec 2012 08:08 AM. Topic has 1 replies.