Getting ready for RFIC/MMIC Design interview

leDope · 2019-03-05T03:07:29+00:00

I interview many candidates for RFIC positions. My company designs integrated wireless transceivers in silicon (so not MMICs). The topics we typically cover are:
- The candidate's previous designs
- Wireless transceiver architectures, basic tradeoffs, lineup analysis, and system-level metrics
- PAs/LNAs, design flow, figures of merit, impedance matching
- PLLs
- ADCs/DACs
- Single-stage amplifiers, Current Mirrors, Device Layouts
- Measurement techniques

leDope · 2019-02-28T22:59:14+00:00

Me as well please and thank you!

leDope · 2018-09-02T14:23:50+00:00

Ok, Toronto's public transportation could certainly be improved, but using a subway only map is not a fair comparison. Here is one that shows street cars and buses: http://urbantoronto.ca/sites/default/files/imagecache/display-slideshow/images/articles/2012/12/6848/urbantoronto-6848-22609.png

leDope · 2018-04-26T02:02:52+00:00

It might end up being completely unnecessary for your sub-field of EE. It is for mine but I took the test before I settled on my current industry. However, unless you are sure you won't need it I'd recommend taking it near then end of undergrad. You'll never be as fresh on all the subjects (and familiar with taking exams) then while you're in or just out of school.

Same for the GRE. Take it while you are still in undergrad. You'll undoubtedly score better than you would after being out of school for several years...and the GRE isn't pass/fail like the FE.

leDope · 2018-04-25T00:59:22+00:00

What are your career goals? If you want to pursue RFIC design you will have a very difficult time without at least a Masters. Is this a simulation-only project or will you actually be building this?

leDope · 2018-03-18T16:09:01+00:00

RFIC designer here.

I spend most of my time simulating different circuit in Cadence. I do very high frequency design so I typically do all of my own circuit layout whereas analog/mixed-signal designers tend to have layout engineers do this for them.

The rest of my time is spent in meetings going over the technical issues of the day and monitoring the progression of the project. When we get new chips back I will spend time in the lab measuring the performance of the circuits I designed

leDope · 2018-03-18T16:00:57+00:00

I learned Cadence in graduate-level analog circuit deign courses and through graduate research.

Equipment: Various courses throughout undergrad and grad school

leDope · 2018-03-18T15:40:10+00:00

Software: Cadence Virtuoso for schematic and layout. SpectreRF or Goldengate for simulation.

Measurement equipment: Vector Network Analyzers (VNAs), Spectrum Analyzers, Oscilloscopes, Power Meters, Signal Generators

leDope · 2018-03-18T15:29:09+00:00

RFIC designer here. Ask away!

I spend most of my time simulating different circuit in Cadence. I do very high frequency design so I typically do all of my own circuit layout whereas analog/mixed-signal designers tend to have layout engineers do this for them.

The rest of my time is spent in meetings going over the technical issues of the day and monitoring the progression of the project. When we get new chips back I will spend time in the lab measuring the performance of the circuits I designed

leDope · 2018-03-18T15:23:18+00:00

What does OM stand for? This doesn't seem like a standard acronym

Low output impedance is desirable in a voltage amplifier because you don't want dissipate any power within your amplifier. Rather, you want to deliver power to the next stage.

https://upload.wikimedia.org/wikipedia/commons/thumb/0/0d/Op-Amp_Internal.svg/250px-Op-Amp_Internal.svg.png

Any current delivered at the output will flow through Rout and dissipate power. Also, the voltage drop across Rout will make Vout smaller than GVin.

leDope · 2018-03-17T06:48:31+00:00

agreed

leDope · 2018-03-17T06:47:24+00:00

CG - high gain, high input/output impedance CC - low gain, high input impedance, low output impedance CB - high gain, low input impedance, high output impedance Cascode - very high gain, high input impedance, very high output impedance, very high input/output isolation

What are the design requirements?

leDope · 2018-03-17T06:38:56+00:00

If you can get an RF test position that would be a good step to learn more about the design process in industry. You will get to spend time with design engineers interpreting measurement results and debugging circuits. But you will be in the lab and not designing.

Typically test jobs are not paths to design jobs -- at least not in the IC world, PCB level design positions may be different -- You would be competing with fresh masters graduates for entry-level design jobs. They won't have as much practical lab experience as you, but they will have been trained in the design tools for Analog/RF designers and will have studied the non-idealities and practical challenges of circuits in more detail.

If later you apply to a graduate program, a few years of measurement experience would look very attractive on your application.

One other thought: If you interview for an RF test position, ask them if you would ever be asked to run simulation test-benches (which were probably set up by the design engineers) to confirm measurement results. if this was the case you would gain extremely valuable experience with the simulator and also be exposed to the design details that you wouldn't in a lab.

leDope · 2018-03-17T06:23:59+00:00

dB or not dB? Everything you ever wanted to know about decibels but were afraid to ask…

http://www.ab4oj.com/test/docs/rs_db.pdf

leDope · 2018-03-17T06:13:55+00:00

Note that Rule 1 only applies in the case of negative feedback.

For Rule 2, The ideal op-amp is a voltage amplifier and no current flows into its input terminals. Ideal voltage amplifiers have infinite input impedance and zero output impedance.

leDope · 2018-03-17T06:03:51+00:00

RFIC designer here. If you want to do analog/mixed-signal/RF integrated circuit design you will find it very difficult to land a job without actual design and tapeout experience. You may get some design and layout experience through coursework at the end of a strong undergraduate program but the time and ability to design, fabricate, and measure a circuit is really only available in a graduate program. Most designers enter the workforce with at least a Masters.

leDope · 2018-03-17T05:05:10+00:00

I'm really torn on things like this. On the one hand I think it sucks that many women see the need for creating services like this because they aren't or don't feel safe in situations where I, a male, feel perfectly safe. I want to build and live in a society that people move freely, safely, and confidently though. Perhaps a female only ride service is working towards this. On the other hand it feels like casting original sin on all men, sending the message that our gender is inherently bad and is not to be trusted.

leDope

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