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!

icsoul said:

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!

Click to expand...

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.

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

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

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

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

icsoul said:

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!

Click to expand...

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

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

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,

fasmatikos said:

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

Click to expand...

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

thanx in advance
chethan

Thanks all of you!
I'm studying.

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

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

according to application

you must understand your specs