Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronics Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

How to solve gm variation problem?

Status
Not open for further replies.

jcpu

Full Member level 4
Joined
Dec 17, 2005
Messages
214
Helped
18
Reputation
36
Reaction score
5
Trophy points
1,298
Activity points
2,968
Dear Sir:

I am reviewing a 4MHz PLL with 6 stages ring of Gm-C cells.
The problems is gm value of these cells varies with process;
and even worse when temperature changes.

What should I do?
 

paulux

Advanced Member level 4
Joined
May 16, 2005
Messages
112
Helped
11
Reputation
22
Reaction score
2
Trophy points
1,298
Activity points
2,339
Re: gm variation problem

use temperature & process compensated circuit in your gm-cell circuit.
 

    jcpu

    Points: 2
    Helpful Answer Positive Rating

jcpu

Full Member level 4
Joined
Dec 17, 2005
Messages
214
Helped
18
Reputation
36
Reaction score
5
Trophy points
1,298
Activity points
2,968
Re: gm variation problem

Dear Paulux

Please suggest some reference paper or circuits?

Thanks in advance!
 

eecs4ever

Full Member level 3
Joined
Jan 31, 2006
Messages
176
Helped
28
Reputation
56
Reaction score
10
Trophy points
1,298
Location
Analog Environment
Activity points
2,838
Re: gm variation problem

**broken link removed**

slide 17.

There is more stuff about it in the grey and meyer textbook.

heres a paper that describes this.



Good luck!
 

    jcpu

    Points: 2
    Helpful Answer Positive Rating

maddy

Junior Member level 1
Joined
Dec 29, 2005
Messages
19
Helped
9
Reputation
18
Reaction score
1
Trophy points
1,283
Activity points
1,480
Re: gm variation problem

Cant we use a constant-gm bias to bias the gm cells? I have seen it maintain constant-gm when I used it in a LNA. Just wondering... Let me know if this is wrong.

Maddy
 

    jcpu

    Points: 2
    Helpful Answer Positive Rating

jcpu

Full Member level 4
Joined
Dec 17, 2005
Messages
214
Helped
18
Reputation
36
Reaction score
5
Trophy points
1,298
Activity points
2,968
Re: gm variation problem

Dear Maddy

In the case of PLL, GM bias circuit are mainly controlled by output voltage
of loop filter which we called "Vtune".
With differnent Vtune, the GM bias should control the GM cell bias current
so as to reduce PFD (phase frequency detector) error.

I have no idea how to compensate (vs temperature or process) practically.
So I posted the question.
Thanks a lot for your suggestion.
 

Status
Not open for further replies.

Similar threads

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Top