What's the fastest VCO delay cell?

[mouzid]

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

 

[master_picengineer]

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.

 

[mouzid]

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

 

[khouly]

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

 

[master_picengineer]

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 ?

 

[khouly]

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

 

[master_picengineer]

VCO Delay Cells

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

 

[mouzid]

Re: 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

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 ?

 

[milkdragon]

Re: VCO Delay Cells

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

 

[mouzid]

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 ?

 

[mouzid]

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 !

 

[master_picengineer]

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 !

Me too,
Bellow is the simulation result.

Who can help.

 

[mouzid]

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 ?

 

[AdvaRes]

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 ?

Reduce the transient maxstep in the transient options window.