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how can simulate this circuit, what is this switch. (by HSpice)

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Mostafa.A

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I should, simulate below circuit by HSpice. but I don't know about below switches(S1 & S2 & S1.YL & S2.Y switches),. and can't simulate this circuit by HSpice.

SECOND-ORDER SIGMA-DELTA MODULATOR.JPG

please help me.

excuse me, for my sentences , because
I'm poor in English
 

andre_luis

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The circuit above contains standard switches.
Pehaps you are misunderstanding the derivation at one side of the component.


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FvM

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There are different levels of simulation. In a functional simulation, you would want to use simple ideal switches. In a real circuit, they
 

Mostafa.A

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if I change them white ideal switches, I don't know, how write function of them.
I don,t know these switch work by what, and how them switching

my problem is, I don't know to do what.
I think, these switch should be replace by a circuit, to can simulate these.

please help me to know, what is these switches?
or how can I get, more knowledge about them .




excuse me, for my sentences , because
I'm poor in English
 
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FvM

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I'm not using HSPICE and can't tell, if it has a generic switch model. The SPICE variants I'm using (PSPICE and LTSpice) have it. As already said, in a real circuit, CMOS switches would be used. Simple NMOS or PMOS switches can be used as well, but there are some disadvantages as limited voltage range and missing charge injection compensation.

I guess, the actual problem behind your question is understanding switched capacitor circuits. I suggest to review respective literature, e.g. the SC chapter in Razavi Design of Analog CMOS IC.

P.S.: Did you understand, that S1 S2 represents a two-phase clock?
 
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andre_luis

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You also need to design a logic control circuit to supply generation of S1/S2 signals and proper timmings.
Not so complex in SPICE.


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Mostafa.A

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Thanks a lot, for your answer.
I understand that S1 S2 represents a two-phase clock. but I don't know how other switches works.
I think, I don't have enough knowledge about switched capacitor circuits.

I read SC chapter in Razavi Design of Analog CMOS IC, and then tell you, In 1 or 2 days ago.
but I don't have this book. can you upload this chapter?


also thanks for andre_teprom answer. this circuit work by 0.9V supply voltage. and I think if I design a logic control circuit, it doesn't work currently.


Best regards.
Mostafa.A
 

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