| Author |
Message |
zahrein
Joined: 28 May 2004
Posts: 144
|
 19 Oct 2004 4:40 how to improve band width and phase margin, unity gain? |
|
|
|
GUYZ,
Can anyone explain how to improve band width and phase margin and unity gain of op amp please?
|
|
| Back to top |
|
 |
adel_48
Joined: 17 Dec 2003
Posts: 333
Helped: 37
|
| 19 Oct 2004 16:08 Re: how to improve band width and phase margin, unity gain? |
|
|
|
I suppose you want to know how to improve band width and phase margin together. The main problem is improving one distroys the other, for example to improve phase margin you may add a compensation capacitor but this necissarily reduces your bandwidth
This effect is mainly due to that most of the methods used to improve the phase margin depend on reducing the gain to unity at the point when the phase shift between the input and the output is 180 - (required phase margin).
you may see Razavi (Analogue CMOS design) for further information. It has a complete chapter about stability and another chapter about Op-Amps
Last edited by adel_48 on 19 Oct 2004 21:10; edited 1 time in total |
|
| Back to top |
|
|
sutapanaki
Joined: 02 Nov 2001
Posts: 488
Helped: 19
|
| 19 Oct 2004 17:08 Re: how to improve band width and phase margin, unity gain? |
|
|
|
| Can you give some more info - is it a descrete opamp you're talking about. Is it a transistor level IC opamp. If so, what architecture do you target?
|
|
| Back to top |
|
|
zahrein
Joined: 28 May 2004
Posts: 144
|
| 21 Oct 2004 1:53 how to improve band width and phase margin, unity gain? |
|
|
|
| This is For 741 op-amp.
|
|
| Back to top |
|
|
Regnum
Joined: 17 Jun 2004
Posts: 264
Helped: 12
Location: Hurlingham
|
| 21 Oct 2004 3:04 Re: how to improve band width and phase margin, unity gain? |
|
|
|
741 is internally compensated.
If you are not using reactive components in the feedback loop and have stability problems, rather check the load capacitance.
|
|
| Back to top |
|
|
ue
Joined: 22 Jan 2004
Posts: 32
Helped: 2
|
| 21 Oct 2004 5:17 Re: how to improve band width and phase margin, unity gain? |
|
|
|
if i remeber correct there are two pins on 741 package which can be connected with R-C circuit and compensation is done.
/ue
|
|
| Back to top |
|
|
Regnum
Joined: 17 Jun 2004
Posts: 264
Helped: 12
Location: Hurlingham
|
| 21 Oct 2004 5:30 Re: how to improve band width and phase margin, unity gain? |
|
|
|
| those pins are for offset adjustment
|
|
| Back to top |
|
|
