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Whats the limitation of using CMOS ?(for analog memory)

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CMOS analog memmory

Hi all.. I am doing a project on analog memmory cells for a convolutional decoder. the basic idea is to use cascading sample and hold circuit with a buffer in between stages.

I am just wondering what is the limitation of using CMOS. and are there methods to improve the limitations?

I should mention that im just an undergraduate and a complete newbie in analog IC. may be you guys can point me to a right direction... :?


Many thanks
 

Re: CMOS analog memmory

The list of non idealities is large, your question seems too general but do not forget to consider if some of the following affect your circuit:
- Charge injection
- kT/C noise
- charge time to your capacitor if your sampling rate is too large
- offset at your buffer opamp

There are plenty of configurations and literature on analog memories. try to read some of these papers. I got some experience on these circuits, you can contact for any other specific question.

Or better start on any basic microelectronics book with the transmission gate.



Ian
 

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    ug02048

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CMOS analog memmory

It's too difficult that you design analog memory.
You can study about digital circuit design by:
A. P. Chandrakasan AND R. W. Brodersen, “Low Power Digital CMOS Design,” Kluwer academic Publishers, 1995.
 

CMOS analog memmory

Thanks guys ,, its not acturally memory memory, I am designing analog shift register using cascading sample and hold for a modified feedback convolutional decoder. can you guys give me some keywords on the limitation on cmos so i can google it? any help will be very much appeciated. :cry:

all I got so far

- Charge injection
- kT/C noise
- charge time to capacitor
- offset at buffer opamp
 

CMOS analog memmory

It depends on the sample and hold structure
that you will use.
Most probably, you will use flip-over
kind of SC sample&hold.
So you have to check
1. kT/C
2. Switch Bandwidth
3. Switch charge injection
4. Switch on resistance
5. Opamp Bandwidth
6. Opamp GBW
7. Opamp offset
8. Opamp finite gain
 

Re: CMOS analog memmory

the noise and the offset is your first problem
 

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