Questions for Dr. Mühlhaus Spiral Inductor Assistant for Sonnet
1. For "round differential" inductors, if i'm creating a single-turn inductor, why does the generated inductor in stadium shape rather than circular? Is there any reason for that?
2. If I have a target frequency for the inductor, how to make sure it'll operate precisely at my bandwidth that I want by using that tool?
3. How does the tool estimate the inductances based on my parameter inputs? will the estimation affected by the shape of the inductor as well?
Thanks.
Hello,
I created this tool long ago and haven't used it for years, but will try to answer your questions.
The simple reason is that layout code makes room for crossover, and doesn't check for the special case N=1.
You can't. My spiral tool for Sonnet was meant to help creating the geometry. Only my next generation tool (Inductor Toolkit for ADS) has more synthesis and automation built into the workflow.
Yes, shape matters. The inductance estimation is based on closed form equations, the math can be found here: https://stanford.edu/~boyd/papers/in...pressions.html
Best regards
Volker
Say I created four single-turn round (stadium) inductors to operate at 60 GHz, all within 68 pH to 104 pH, and I've simulated them with Sonnet, they somehow reached my targeted inductance with decent Q-factors (>20) at 60 GHz, how was that possible?
I don't understand your question. My spiral tool for Sonnet creates a layout based on the dimensions that you - the user - enter into the tool. It gives you feedback on estimated inductance (using textbook equations, see #2). That estimated inductance is calculated for DC, so the accuracy of that estimation depends on how "flat" inductance is in that frequency range, i.e. how close your target frequency is to the inductors self resonance.
How good that inductor performs at your target frequency (Q factor) depends on the user's choice of parameters. So this early tool requires a user who understands what parameters to change if the peak Q frequency is too low/too high. My next generation tool has a lot more automation to find the best parameter combination, and also accounts for that frequency dependence mentioned above (compensate increase in inductance over frequency). With the first generation tool (Spiral Inductor Assistant for Sonnet) you need to take care of these effects yourself.