sigma delta ADC

[beheshte]

Hi, I'm new here. I will be appreciated if anyone can help me.
I want to design a discrete-time noise-coupled sigma delta modulator. so I need an adder before the quantizer, that has a path with one cycle delay. In the articles I've seen, this adder is realized with an active adder. Is it possible to realize it with a passive adder? I mean is there a passive adder which has a path with one cycle delay?
thanks

 

[Harald Kapp]

What do you mean by active or passive adder?
Can you show us a reference circuit diagram so we talk about the same things?

 

[beheshte]

To realize an active adder we use an Op-Amp and some switches and capacitors but a passive adder doesn't need an Op-Amp.It is realized just with some switches and capacitors.
In the paper called "ΔΣ ADCs with Second-Order Noise-Shaping Enhancement" figure.4 shows an active adder with one cycle delay.This is the address of the above paper:
http://ieeexplore.ieee.org/xpl/logi...5230480/5235877/05236085.pdf?arnumber=5236085
I want to realize this circuit without using an Op-Amp, I mean by a passive adder.

 

[beheshte]

And also in the paper addressed below,figure.16 and figure.17 shows a passive and active adder respectively:
http://onlinelibrary.wiley.com/doi/10.1002/cta.1816/abstract
In fig.16 the switches and capacitors at front end make the passive adder.The Op-Amp after that does not belong to the passive adder .That is preamp for the quantizer and can be removed.

 

[KrisBlueNZ]

Neither of those documents is accessible without a membership to the web site.

 

[Harald Kapp]

I don't know of a "passive adder" (in your terms) that would be reasonably accurate for use in an ADC.
I, too, do not have access to the linked documents.

 

[beheshte]

I will send you these articles if you could give me your email addresses

 

[Harald Kapp]

Do not send them to any of us, post them here using the attachment function (you need to "go advanced" for this).
On the other hand, since these articles are behind a paywall, they are most probably copyrighted. Make yure you have the right to post them or to send them to others. Or redraw the relevant schematic parts to avoid copyright infringement.

 

[beheshte]

These articles are free for the students of our university because our university is a member of those websites. So they paid for them.But I'm not sure that I can share them. That was the reason that I wanted to send them as an email for you, not to share them in a public website. So if it is possible for you,I send them for you as an email.
thanks anyway

 

[Harald Kapp]

Please do not send them. rfedraw the relevant schematic and post it on the forum so others too can see it.

 

[beheshte]

I attached a file that includes the circuit diagram of mentioned adders