VCO design and measurement

STOIKOV said:

hello! I designed a ring vco, simulated and did its layout. Then I simulate the extracted circuit (LEdit) and simulated again to obtain a frequency against control voltage curve. So the chip was fabricated and the experimental results show that the oscillation frequency is about 15 or 20% above the simulation frequency.

I hoped to obtain in lab a frequency below the simulated, maybe due to other parasitics not considered, but the frequency measured is larger.

Is this a normal behavior ? How can I justificate this percent of error. I was thinking on process variations, what do you think ?

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STOIKOV said:

what means simulate in "fast corner" ?

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STOIKOV said:

I'm using a Mosis process, the fast model is a simulator option or a complete model like level=49 that currently am using ?

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henryhd said:

I want design a ring oscillator,can you provide me some tutorial by ADS. and i want to know how can i builde the MOS component i need,and my operated frequency is about 5GHz!thank you!

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STOIKOV said:

hello! I designed a ring vco, simulated and did its layout. Then I simulate the extracted circuit (LEdit) and simulated again to obtain a frequency against control voltage curve. So the chip was fabricated and the experimental results show that the oscillation frequency is about 15 or 20% above the simulation frequency.

I hoped to obtain in lab a frequency below the simulated, maybe due to other parasitics not considered, but the frequency measured is larger.

Is this a normal behavior ? How can I justificate this percent of error. I was thinking on process variations, what do you think ?

Click to expand...