Antenna Diodes in the Pentium Processor
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Antenna Diodes in the Pentium Processor
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Re: Antenna Diodes in the Pentium Processor
#2Author here: I know this is a very obscure topic, but hopefully it will be interesting to some. Let me know if there are any questions...
Re: Antenna Diodes in the Pentium Processor
#3Are the antenna diodes only there to reduce damage during manufacture or is there also impact runtime in an electromagnetic noisy environment?
Re: Antenna Diodes in the Pentium Processor
#4Author here: I know this is a very obscure topic, but hopefully it will be interesting to some. Let me know if there are any questions...
Absolutely fascinating!
It’s precisely these orthogonal, secondary concerns that make every industry more difficult than people on the outside might think.
Articles like yours shed light on these challenges.
I’m reminded of a recent project working on a (small!) data warehouse where for the first time in my career I had to not only be concerned with theoretical performance of queries, such as the presence or absences of indexes, but orthogonal concerns such as the time taken to rewrite terabytes of data on disk during night ETL jobs… combining with the “change rate” of the source data.
Your article is a similar concern that only specialists in the in the industry are even aware of: it’s not enough to logically route connections — a challenging optimisation all by itself — but there are these competing physical optimisation issues as well that need to be simultaneously optimised!
Re: Antenna Diodes in the Pentium Processor
#5Are the antenna diodes only there to reduce damage during manufacture or is there also impact runtime in an electromagnetic noisy environment?
The antenna diodes are only relevant during manufacturing, when a metal line is connected on one end but not the other. ESD diodes on the other hand protect inputs against electrostatic discharge when the chip is in use.
Re: Antenna Diodes in the Pentium Processor
#6Are the antenna diodes only there to reduce damage during manufacture or is there also impact runtime in an electromagnetic noisy environment?
I thought they were there to allow Van Eck phreaking of the processor state
Re: Antenna Diodes in the Pentium Processor
#7Fun fact about "antennas" in chip manufacturing: They have nothing to do with actual antennas. Charge can build up on long wires during manufacturing because the chemicals involved are not neutral and have some interactions with exposed wires. That charge needs to go somewhere to protect the rest of the circuits. There's nothing RF about this.
Later technologies (28 nm and below) have extensive design rules around prevention of "antenna" effects.
Re: Antenna Diodes in the Pentium Processor
#8Fun fact about "antennas" in chip manufacturing: They have nothing to do with actual antennas. Charge can build up on long wires during manufacturing because the chemicals involved are not neutral and have some interactions with exposed wires. That charge needs to go somewhere to protect the rest of the circuits. There's nothing RF about this. Later technologies (28 nm and below) have extensive design rules around pr…
I think that’s incorrect. The article and the Wikipedia page on the antenna effect say antenna effects are caused by plasma etching, which uses RF to create the plasma.
Re: Antenna Diodes in the Pentium Processor
#9Now go look at the need for antenna diodes in SOI technology:) with the substrate no longer the safe haven, a lot more oxides can be exposed to large differential voltages during manufacturing.
Re: Antenna Diodes in the Pentium Processor
#10Are the antenna diodes only there to reduce damage during manufacture or is there also impact runtime in an electromagnetic noisy environment?
There is a tiny amount of extra capacitance on the net because of the reverse-biased junction of the antenna diode, but that's it. These diodes do get taken into account in when determining timing though.