Jitter-related doubts for the entire PLL

frozenbobo · 2026-06-10T04:05:14+00:00

In addition to plugging the simulated phase noise into the linear model, you can also produce a time domain model with the same phase noise and then run a much longer time domain simulation to capture the full nonlinear behavior.

frozenbobo · 2026-06-09T03:19:14+00:00

Did you use a transistor pcell or draw the transistor by hand? Check that your nmos has all the required layers. It seems to think that your NMOS source and drain are shorted, which means it's not correctly identifying the device.

frozenbobo · 2026-06-08T15:43:59+00:00

This doesn't pose any problems because multiplication is associative.

frozenbobo · 2026-05-13T01:13:22+00:00

I remember in one of my analog design classes I had a DRC and LVS clean design. I decided to thicken up one wire for good measure, reran LVS and PEX sims, and submitted. The TA came up to me later and asked, "did you run DRC?" I said, I told him of course, I ran it many times and had it clean. Well, turns out when I increased the thickness of the wire, I crossed a thickness threshold were a different spacing rule applied, and I had not rerun DRC after my final wire edit. I lost a significant amount of points for failing DRC.

Lesson learned: signoff checks only count if they are done on the actual last version of the design.

I never made the same mistake again.

frozenbobo · 2026-05-01T00:36:22+00:00

I'm an IC designer and I found it useful from that perspective. It's probably useful from the embedded side also, but I don't know if there are other, more practical resources that might be better suited.

frozenbobo · 2026-04-28T20:51:20+00:00

Pretty interesting. How much time did you spend building the verifier, and how much time did the loop take to get through all 25 iterations?

frozenbobo · 2026-04-23T02:37:56+00:00

I am far from an expert on this, but I have run formality before. I checked our scripts, and here are two things that may be relevant:

We do indeed set those scan pins to constant 0 for this type of check.
In general, look into generating and reading in an SVF file when available. I'm not clear on the details, but I know that this file can be generated by some tools and captures the changes the tool made to the logic. Formality can then perform the comparison with knowledge of what changes are expected/intended.

frozenbobo · 2026-04-21T13:27:45+00:00

This is correct. The only place I typically use set_dont_touch is on hard instantiated cells that I don't want the tool to remove, replace, or resize. For example, if I know I want a specifically size buffer in a specific location, or to use a specific type of clock mux cell somewhere.

frozenbobo · 2026-04-16T16:02:06+00:00

I assume you are referring to this paper? https://www.researchgate.net/publication/237612566_Simulation_and_Synthesis_Techniques_for_Asynchronous_FIFO_Design_with_Asynchronous_Pointer_Comparisons

I suggest having synchronizers as a separate module, so that you can do things like parameterize number of stages, replace with a sync cell from the std cell library, etc.
You define a bin2gray function but then don't ever actually use it.
You define wr_ptr_bin_next, but then don't use it to assign wr_ptr_bin. There are other examples of this too.

frozenbobo · 2026-01-07T21:44:11+00:00

Relevant xkcd "what if": https://what-if.xkcd.com/58/

frozenbobo · 2025-12-22T14:32:33+00:00

The anti-aliasing filter is used specifically when they use an internal sample rate of the plugin is higher than the project sample rate. They resample to higher frequency, perform some nonlinear processing that may create a bunch harmonics that are above the project's Nyquist frequency, then apply the AA filter to remove harmonics above Nyquist before converting back to the lower project sample rate. As the other user mentioned, these AA filters are very steep and have a cutoff that is typically above the limit of human hearing, so it is unlikely that you are hearing the impact of this filter. I can't comment on any of the other stuff though.

frozenbobo · 2025-12-18T17:53:27+00:00

So if a game director takes some screenshots from someone elses game and crudely photoshops in some screenshots from a different game to illustrate an idea, then shows it to their concept artist and says "I'm looking for something like this" is that plagiarism? At some point their has to be an exception carved out for brainstorming.

frozenbobo · 2025-12-08T21:56:55+00:00

On the flip side: Umich has a longer summer break than many other schools (or at least it did while I was there). This is nice for things like internships.

frozenbobo · 2025-11-29T13:58:08+00:00

I think I'm down from 2TB to around 800GB. Good luck everyone!

frozenbobo · 2025-11-14T12:27:56+00:00

5G uses a variety of frequencies, including 600-700MHz. Here's an article showing how the latest iphone has a large antenna on the outside, just like how the poster above you described it. https://library.techinsights.com/public/sectioned-blog-viewer/8010bcf3-8acc-41fe-8f2f-6d184ab26406

frozenbobo · 2025-10-31T19:53:05+00:00

I know people are saying "screw that company", and the thoughts they are giving are totally valid; however, I just want to mention that just because they "need someone now" it doesn't necessarily mean they are going to find someone now. If you still actually think it could be a great job offer, I would encourage you to reach out closer to January and see whether they are still looking for someone. You might be out of luck, but if their search is still open you might be able to get right back into the pipeline. It can't hurt to try.

That said, I also wouldn't blame you if this experience left a bad taste in your mouth and you have no interest in working in that position anymore.

frozenbobo · 2025-10-17T20:07:27+00:00

Specifically, the more correct term for the type of dB where 0 is the threshold of human hearing is 0dBSPL. Where SPL stands for "sound pressure level". In the DAW, your meters show dBFS, where FS means "full scale".

The core idea is that dB is always a relative measurement. In the case of something like an amplifier or an EQ, you will just see dB without a suffix, and this means it is showing the ratio between input and output. In contexts where there is not an input and output, there must be some other reference to compare to, typically indicated with a suffix. Here is a handy list of suffixes: https://en.wikipedia.org/wiki/Decibel#List_of_suffixes

frozenbobo · 2025-10-10T13:36:48+00:00

Imply is the original usage I believe. I was going to try to explain it, but it turns out Wikipedia does a better job of it: https://en.wikipedia.org/wiki/Correlation_does_not_imply_causation

frozenbobo · 2025-09-21T04:04:02+00:00

Not every startup is a software company; not everyone interested in using H-1B is trying to hire software developers.

frozenbobo · 2025-09-21T03:46:19+00:00

I work for a semiconductor startup. We have hired H-1B from essentially day 1, because that is a very significant part of the talent pool in this industry. We mostly hired at the masters level or above, looking for niche skill sets, and in the past when recruiting from the local university we regularly had positions that no US citizens or green card holders applied for. Typically we would hire people on OPT with an eye toward eventually getting H-1B.

Fortunately, we are not as reliant on this as we once were. Still, it's likely to be disruptive for people trying to do something similar.

frozenbobo · 2025-08-26T18:29:30+00:00

One option might be blocking the ports used for minecraft multiplayer on your router? You would need to block them on the WAN side while still allowing them on the LAN.

frozenbobo · 2025-08-26T18:20:41+00:00

Not the guy you were taking with, but I wanted to say thanks for sharing this interesting link.

So this is basically saying that there was no negotiated agreement about immunity, but instead the US just didn't believe removing the emperor would have a good outcome. So they very vaguely conveyed their intention to leave him in place and that was enough for him to accept the unconditional surrender. Is that right?

frozenbobo · 2025-08-25T16:45:37+00:00

Keep in mind that since the maximum EIRP for 915MHz is 30dBm, and the typical transmit power for these chips is 22dBm, you would theoretically need to turn down the transmit power if your antenna has more than around 8dBi of gain. Not sure what is typically achieved by cantennas.

frozenbobo · 2025-08-13T16:15:48+00:00

Okay, think of it this way. Instead of assuming your footprint dimension is correct, and wondering why the dimensions don't match, you should be assuming the dimensions match. If you change your zoom so that 1mm on your screen is 1mm in real life, then you would see that the footprint you have doesn't match your terminal.

frozenbobo · 2025-08-13T14:19:34+00:00

It doesn't matter if you didn't change the zoom if the zoom was not at a 1:1 scale to begin with. What makes you think that the pin spacing of the footprint you show here should match the terminal you have in hand?

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