The Designer's Guide Community Forum

The Designer's Guide Community Forum
https://designers-guide.org/forum/YaBB.pl
Design >> RF Design >> What we trace off between 3 stage / 4 stage RCO?
https://designers-guide.org/forum/YaBB.pl?num=1131276210

Message started by neoflash on Nov 6^th, 2005, 3:23am

Title: What we trace off between 3 stage / 4 stage RCO?
Post by neoflash on Nov 6^th, 2005, 3:23am

I am thinking about what we trade off between 3 stages and 4 stages of RCO. I am talking about simplest ring oscillator with P-mos triode resistor tuned by bias current.

1. max frequency: 3-stage can achieve higher frequency.
2. noise: 3-stage should be less noisy due to less device.
3. Gain: 3 stage need more DC gain.

I do see several papers and designs used 4 stage RCO, any reason we use that?