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What's the fastest VCO delay cell?

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M

mouzid

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Hi all,
Who can tell me what is the most recent/quick CMOS delay cell nowadays ?
Thanks in advance.
 

Re: VCO Delay Cells

Hi,
I think that the one which has the less transistor count is speeder. Please correct to me if I am wrong.
see figure bellow.
 

    M

    mouzid

    Points: 2
    Helpful Answer Positive Rating
VCO Delay Cells

Dear members,
I'll donate 20 Point for a real help. Here are my questions:
1- Can you explain how a delay cell work.
2- Can someone tell me how to calculate the delay of this gate. And how to find this result by simulation ? (Please upload a shematic using a delay cell in order to determine the delay introduced by this cell)

Thanks in advance
 

    V

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VCO Delay Cells

how the delay cell work

the delay cell is simple a current controlled inverter , but changing the curent , u will change the propagation delay of the inversting amp ,

so by changing the control voltage in the pic , u will chnage the current following in the cell , and change the delay

khouly
 

    M

    mouzid

    Points: 2
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VCO Delay Cells

Chokran jazeelan Khouly,
Could you please tell as how to use this gate ?
I found the schematic in internet and i'm still wondering what the differents Pins stands for ?
 

    M

    mouzid

    Points: 2
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VCO Delay Cells

this gate u need to use 4 of them , to constuct a differental current controlled ring oscillator ,

the input for this circuit is differential and the output is fully differential as well

khouly
 

    M

    mouzid

    Points: 2
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VCO Delay Cells

Thanks,
And the Vc input of the transistor M5 ? What is it's utility ?
 

    M

    mouzid

    Points: 2
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Re: VCO Delay Cells

khouly said:
this gate u need to use 4 of them , to constuct a differental current controlled ring oscillator ,

the input for this circuit is differential and the output is fully differential as well

khouly
Click to expand...

Thanks Khouly, you too master,
I'm waiting for other members to reply.


I know that the Delay cells are used to construct the VCO. However I don't know how much delay they introduce. Moreover I'm planning to design a VCO using a delay cell. So knowing at an early stage the amount of the delay I can compute what is the appropriate number of delay cell and the maximum frequency.
Could you please my friend respond to my previous questions now ?
 

Re: VCO Delay Cells

To calculate the delay, you have to essentially calculate all the equivalent R and C at the output node
 

Re: VCO Delay Cells

Hi friends,
i wanna design a VCO using the delay cell proposed by master_picengineer. Is this Interconnection of the discussed Delay cell is right ?
 

Re: VCO Delay Cells

I constructed the above circuit. For Vc < 0.6 V there is no oscillation. For Vc > 0.6 I could see a very weak triangle oscillation with an amplitude of 1 nano Volt.

I don't understand why it does not work.

Please Help !
 

Re: VCO Delay Cells

mouzid said:
I constructed the above circuit. For Vc < 0.6 V there is no oscillation. For Vc > 0.6 I could see a very weak triangle oscillation with an amplitude of 1 nano Volt.

I don't understand why it does not work.

Please Help !
Click to expand...

Me too,
Bellow is the simulation result.

Who can help.
 

    M

    mouzid

    Points: 2
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Re: VCO Delay Cells

Here is my simulation using a 65 nm lib.

I need to reduce the period T and the rise fall time of this signal. Also I have to have an ampliture of about 1 V.
Please tell me how to proceed ?
 

Re: VCO Delay Cells

mouzid said:
Here is my simulation using a 65 nm lib.

I need to reduce the period T and the rise fall time of this signal. Also I have to have an ampliture of about 1 V.
Please tell me how to proceed ?
Click to expand...

Reduce the transient maxstep in the transient options window.
 

    M

    mouzid

    Points: 2
    Helpful Answer Positive Rating
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