Phase shifting without the use of DLL or PLL

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anssprasad

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dll phase 90

Hi

I would like to know if we can get a 90 degree phase shifted clock from the reference clock without using PLL or DLL

Thanks
Prasad.
 

phase shift dll

If you know the frequency of the reference clock then you can use a delay circuit with a buffer. The delay circuit can be a simple RC circuit combined with a buffer to reshape the square wave.
 

kishore2k4 said:
If you know the frequency of the reference clock then you can use a delay circuit with a buffer. The delay circuit can be a simple RC circuit combined with a buffer to reshape the square wave.
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wouldn't this be PVT dependent ??
 

Can you please tell me what you meant by PVT
 

If you can generate double the required frequency, then a master-slave flip-flop can be used as a by 2 divider .The output of the master latch will by leading by 90 degrees the output of the slave latch .But this relies on the ability of having double the required frequency .
 

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    anssprasad

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You can generate double the frequency clock by using an XOR gate and a delay chain. Hook up the undelayed clock to one XOR input and delayed to the other, you will get a clock at twice the speed (but not 50-50 duty cycle), also the jitter of this clock will depend on the duty cycle of the original 1X clock (so it is important to make that one as close to 50-50 as possible). You can now divide the 2X clock by two and depending on your initial state and time reset to the divider is de-asserted you can get the required phase shift.
 

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