problem understanding Rotary Traveling-Wave Voltage Controlled Oscillator principle

Thread Starter

yef smith

Joined Aug 2, 2020
717
Hello, I am trying to understanf the following sturture in the thesis link shown bellow.
i know that cross back coupled pair oscilator generates a sine wave .
-Gm is cancelled with tank resistance to get the barkausen condition.
Ho does this combination of ring transmission line and oscilator structure work together to get the desired result?
Thanks
https://knowledgecommons.lakeheadu..../4817/SunF2021m-1a.pdf?sequence=1&isAllowed=y
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nsaspook

Joined Aug 27, 2009
13,087
It's basically using the ring structure as a set of connected transmission delay lines for the phase-shift required for oscillation. The inverter pairs act as triggered switched energy sources at the phase shift nodes.
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https://cseweb.ucsd.edu//classes/wi06/cse291-b/slide/let8/rotary.pdf
3.2.4 Circuit Design Two transmission line segments are shown in Fig. 3.9. The length of all transistors in this section has been chosen to be the shortest possible. The gain stages change power consumption and monitor rotation directions. During start-up, the direction control bit, ”dir” and an activate signal, ”en” decide the traveling-wave direction. Via a series of inverters, either the clockwise or counterclockwise control of each direction control module is delayed by approximately 1 ns. The direction control signal, when combined with 4-bits power control signals, sets NMOS/PMOS switches of cross-coupled pairs ”ON/OFF” in a sequential manner, allowing the NMOS/PMOS pairs to be switched ON/OFF under the direction control signals and 4-bits power control signals. When the RTWO is oscillating, the direction control bits store the value before the next start-up, and the power control signals decide power consumption. The oscillation’s maximum power usage indicates that all four bits are ”1” while the minimum power setting keeps the oscillation running. It is worth noting that setting the delay time at random will result in direction control failure. For two gain stages in each transmission line bank to be switched on, the delay cell must be correctly sized to provide 1 ns delay.
 

Thread Starter

yef smith

Joined Aug 2, 2020
717
Hello nsaspook,coherent signals have the same phase.
non coherent is that dont have the same phase.
Suppose we have only 1 sourcei marked 1 and no other .
It cteates some osilation (wave) which propogates to a transmition line.
our propogating signal when we criss cross the transmission line gets a phase of 180 degrease.
Why do we add several criss crossed pairs in parralell to eah other?
Thanks.
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