6.776  High Speed Comm Circuits

Project 2 and Course Evaluation

Dear Class,

Following the previous announcement, in your PSS simulation for phase noise, you may select an option "oscillator" in the pop-up window. You may also need to remove your current pulse source if PSS refuses to proceed (you still need it for your transient simulation).

Also a friendly reminder that the course evaluation deadline is Dec. 17. Since we don't have many students, it is important that you provide your feedback for the class. Thank you!

Happy Holidays,

Ruonan

Announced on 14 December 2018  9:01  a.m. by Ruonan Han

Simulation for Oscillator

Dear Class,

Some of you reported that your oscillators did not oscillate in the simulator, or oscillate with a small swing but then die out.

Recall that oscillation starts with a "disturbance" or noise containing the right frequency component, which satisfy oscillation criteria in a round trip. In our simulator, the beginning of the transient response is computed based on the initial DC condition. However, due to the perfect symmetry of your oscillator, no "disturbance" exists, hence it is possible that no oscillation would grow from that.

So, the suggested solution is to intentionally add an impulse **current** which injects some charge into the oscillator in an unbalanced way (e.g. only inject to one side of your oscillator). You can use a current source with square-wave output, and set the duty cycle to be small (say 0.5 ns), and the period to be very large (say 1us). Remember to also set the rise/fall time to be proper.

Then, you should be able to see that with such "kick", oscillation starts nicely. If you still don't see that, maybe your design is incorrect.

Thanks,

Ruonan

Announced on 13 December 2018  8:31  a.m. by Ruonan Han

Q & A Session Tomorrow

For the preparation of the quiz, if you have any question to ask, including the past homeworks and quiz, feel free to stop by (39-527A) tomorrow between 3pm~4:30pm.

Thanks,

Ruonan

Announced on 05 December 2018  8:27  p.m. by Ruonan Han

About the PLL Dynamics in Lecture Note 15

In the printed version of Lecture Note 15, the curves of phi_out of the PLL on Page 3 and 4 (from a textbook) seem missing. If you check the posted PDF version, you can see that phi_out is related to a light grey curve is has partial overlap with that of phi_in. The color was too light that it did not show in the printed version.

Ruonan

Announced on 05 December 2018  2:48  p.m. by Ruonan Han

Course Evaluation

Hi, Class,

You may have received a request of providing your evaluation for the class (6.776). I strongly encourage you to do so, because this will help us improving the teaching quality.

Thank you!

Ruonan Han

Announced on 03 December 2018  11:00  a.m. by Ruonan Han