How to design a good differential amplifier?

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icsoul

Joined: 28 Nov 2005
Posts: 72
Helped: 3

15 Mar 2006 8:58 How to design a good differential amplifier?

Where should I begin from?
How to define the basic parameters?
How to simulate the circuit completely?

papers,datum,advice etc all welcome!

Thanks very much!

sixth

Joined: 16 Feb 2006
Posts: 84
Helped: 10

15 Mar 2006 9:33 Re: How to design a good differential amplifier?

icsoul wrote:

Where should I begin from?
How to define the basic parameters?
How to simulate the circuit completely?

papers,datum,advice etc all welcome!

Thanks very much!

What a good opamp? The first requirement for a good opamp is that it must be suitable for one's applications. Then next requirement is that its cost and power consumption should be as lower as possible.
To design a opamp, the first step is to understand its specifications, such as input common mode range, output swing, slew rate, bandwidth, gain, phase margin,etc.
Then, the next step is to determined which structre should be used according to the parameters required by the applications. For example, If your application need deal with a signal whose common mode is always above the middle supply, you shoud select a NMOS transistor as your input stage.
The third step is to calculate the basic parameter tail curren, gm of input stage, output driven capability.
The fourth step is to simulate your design using CAD tools. The DC. AC. and tran simulation must be done for a opamp. During simulation you can find if you design has met the requirement of your applications, if not, modify the deisgn and simulate again until everhing is ok.

mircea

Joined: 07 Sep 2005
Posts: 40
Helped: 2
Location: Romania

15 Mar 2006 12:10 Re: How to design a good differential amplifier?

hi,

it depands what you want do use it for...
here are some books you might want to check:

CMOS Analog Circuit Design by Phillip E. Allen,

Design of Analog Integrated Circuits and Systems by Kenneth R. Laker and Willy M. C. Sansen.

these are very good books. check the opamps chapters.

rgds,
M

obi1

Joined: 02 Mar 2006
Posts: 49
Location: Romania

15 Mar 2006 13:54 How to design a good differential amplifier?

i think the more important thing in layout is matching and the parasitics and finaly the area consumed

phoebe

Joined: 03 Jun 2003
Posts: 11

16 Mar 2006 2:55 How to design a good differential amplifier?

I think the most important is for your application, no one can have all the best parameter .

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fasmatikos

Joined: 05 Nov 2004
Posts: 82
Helped: 3

16 Mar 2006 22:32 Re: How to design a good differential amplifier?

just have a look in microelectronic circuit design by jaeger , you will have no questions left!

husseinadel

Joined: 25 Jan 2006
Posts: 184
Helped: 12
Location: EGYPT,CAIRO

20 Mar 2006 1:29 Re: How to design a good differential amplifier?

icsoul wrote:

Where should I begin from?
How to define the basic parameters?
How to simulate the circuit completely?

papers,datum,advice etc all welcome!

Thanks very much!

there is book "cmos analog ic design" by razavi,, it has a complete chapter on differential amplifiers,,and comprehensive examples with step by step design problems.......search for it in the edaboard...it is great

montage3000

Joined: 03 Mar 2006
Posts: 68
Helped: 1

26 Mar 2006 9:02 How to design a good differential amplifier?

accoding to your application, gain ,BW, PM are important

ahmad_abdulghany

Joined: 12 Apr 2005
Posts: 1369
Helped: 212
Location: Cairo, Egypt

10 Apr 2006 0:23 Re: How to design a good differential amplifier?

If you know basics, and wanna know good design steps sample, then,
Read the full telescopic and folded cascode examples in Razavi's books,

Regards,
Ahmad,

Chethan

Joined: 11 Jul 2005
Posts: 199
Helped: 9
Location: Bangalore

10 Apr 2006 7:54 Re: How to design a good differential amplifier?

fasmatikos wrote:

just have a look in microelectronic circuit design by jaeger , you will have no questions left!

Hi,
do u have this book. can u upload this book.

thanx in advance
chethan

icsoul

Joined: 28 Nov 2005
Posts: 72
Helped: 3

29 Sep 2006 11:13 How to design a good differential amplifier?

Thanks all of you!
I'm studying.

where can i get the book microelectronic circuit design by jaeger ?

timo67

Joined: 21 Sep 2006
Posts: 69
Helped: 3

29 Sep 2006 12:49 How to design a good differential amplifier?

Differential amplifier (and not Operationnal amplifier)!
here are parameters you have to know with precision
1 the differential mode Gain
2 CMRR common mode rejection ratio
3 Input impedance
4 Output impedance
5 Bandwidth
6 Offset
7 power consumpltion
8 output voltage swing needed
...

All these parameters must be specified before you begin any conception work

Hope I help you

Timo67