This application incorporates by reference and claims the benefit of U.S. application Ser. No. 12/465,890, titled “INDUCTANCE ENHANCED ROTARY TRAVELING WAVE OSCILLATOR CIRCUIT AND METHOD”, filed on May 14, 2009, which application claims priority to and incorporates by reference U.S. Provisional Application 61/053,637, filed on May 15, 2008, titled “INDUCTANCE ENHANCED ROTARY TRAVELING WAVE OSCILLATOR CIRCUIT AND METHOD.”
The present invention relates generally to rotary traveling wave oscillators and more particularly to an inductance-enhanced version of such oscillators. Additionally, the invention relates to improvements to inductors.
Rotary traveling wave oscillators (RTWO) are described in U.S. Pat. No. 6,556,089, which is hereby incorporated by reference in its entirety.
One embodiment of the present invention is interleaved rotary traveling wave oscillators. The interleaved oscillators include a first rotary traveling wave oscillator and a second rotary traveling wave oscillator. The first rotary traveling wave oscillator (RTWO) includes a first pair of conductors and a first crossover, with the first pair connected with the first crossover to form a first closed loop. The second rotary traveling wave oscillator (RTWO) includes a second pair of conductors and a second crossover, with the second pair of conductors connected with the second cross over to form a second closed loop. The second closed loop occupies approximately the same physical area as the first closed loop; and the conductors of the first and second crossovers are spaced apart and parallel to each other over a sufficient length that the inductance of the crossovers is increased.
One advantage of the present invention is that the power needed to operate the oscillator is decreased.
Another advantage is that the phase noise is improved.
Yet another advantage is that interleaved oscillators are naturally phase-locked.
Yet another advantage is that the area required for multiple oscillators is not substantially increased over that required for a single oscillator.
These and other features, aspects and advantages of the present invention will become better understood with regard to the following description, appended claims, and accompanying drawings where:
An important property of the embodiment illustrated in
Increasing the inductance of the transmission line leads to an increase in the impedance of the line according to the relationship Z0=√{square root over (L/C)}, where L is the differential inductance per unit length and C is the differential capacitance per unit length of line. For example, increasing the inductance by a factor of four and holding the capacitance unaltered, increases the impedance by a factor of two. The higher impedance of the line has some very positive effects. One benefit is that the power of a wave on the line is reduced by a factor of two, because half as much current is needed for a given differential voltage between the conductors. Another effect is that the phase noise is improved by about 3 dB, which is equivalent to twofold improvement. The phase noise improvement stems from an improvement in the Q factor (Q=ωL/R). Specifically, due to the inductance enhancements, the inductance per unit length increases by about a factor of four, but the series resistance of the line doubles. This causes a doubling in the Q, and thus a lowering of the phase noise. If a figure of merit for oscillators can be defined as the product of the power and phase noise, then the change in the figure of merit for the embodiment of
In either embodiment, the vertical runs of a section have a different spacing compared to the horizontal runs. If the construction of the lines is the same, this makes the Z0 of a vertical run different from that of a horizontal run, causing reflections at the point of mismatch. Let the relationship between the inductances be Lh=nLv (where n is about 4, due to the enhancement) and the relationship between capacitances be Ch=mCv (where m<1 due to the relative distances), where the “h” subscript refers to a horizontal run and the “v” subscript refers to a vertical run. Then, the relationship between impedances is Zh=Zv√{square root over (n/m)}, indicating the presence of a significant mismatch when m is different from n. To correct the mismatch, the relationship between the capacitances must be altered so that Ch is about n times larger than Cv. One way to do this is to increase Ch by increasing the width of the horizontal run. Another way is to decrease the width and thus the Cv of the vertical run. Of course, both changes can be made as well.
Multiple Oscillators
Multiple RTWOs may occupy substantially the same area in accordance with
As mentioned above, for the inductance enhancement to occur, conductor currents in the crossover area of the oscillators must flow in the same direction, which requires that the oscillators be phase locked to each other. Phase locking occurs naturally because each oscillator is naturally influenced by the other oscillators through the magnetic fields generated by the oscillators. With phase locking and each oscillator having a wave traveling in the counter-clockwise direction, the following voltage differences arise.
VAn=−VAp, (1a)
VAn′=−VAp′, (1b)
VBn=−VBp, (1c)
VBn′=−VBp′. (1d)
Furthermore, as the voltage wave travels along the pair of conductors for each oscillator, its wave front creates a voltage difference along the conductor as well, because the wave alters the voltage between the conductors. The voltage differences along a length of each conductor are:
VAp′=VAp+ΔVA (2)
VBp′=VBp+ΔVB (3),
where ΔVA is the voltage difference along the Ap conductor and ΔVB is the voltage difference along the Bp conductor. Combining the voltage differences between the conductors from Eq. (1) with Equations (2) and (3) gives:
VAn′=VAn−ΔVA (4)
VBn′=VBn−ΔVB (5),
which are the equations for the voltage differences across the An and Bn conductors. Equations (2), (3), (4), and (5) now imply that
VAp′>VAp, VAn>VAn′, VBp′>VBp, VBn>VBn′. (6)
Therefore, current flows from Ap′ to Ap, from An to An′ from Bp′ to BP, and from Bn to Bn′, i.e., all currents flow in the same direction, which is shown in
As described, locating the conductors next to each other as shown in
The increase in inductance described herein leads to an important beneficial effect—it lowers the power consumption of the oscillators. The reason is that the increase in inductance L of the conductors of each oscillator causes impedance Z encountered by wave traveling between the conductors of each oscillator to be larger, because Z˜√{square root over (L)}. The higher impedance lowers the current in each oscillator and thus the power P consumed by each oscillator because P˜V2/Z, where V is the magnitude of the traveling voltage wave on each oscillator and Z is the increased impedance.
However, besides lowering the power another effect occurs. Each oscillator has lower phase noise, because each of the oscillators couples to the other through a small impedance, which is the impedance of the inductive coupling described above. In the case of coupling impedance between RTWOs, the impedance is effectively absorbed into the impedance of each RTWO making the coupling impedance nearly zero. This is highly desirable because a smaller coupling impedance leads to a greater the reduction in phase noise for each oscillator, each oscillator having a greater effect in stabilizing the other oscillator or oscillators. If the coupling impedance were zero, then each oscillator would achieve a reduction in phase noise of 3 dB. Thus, the design described herein approaches this limit. As an alternative, instead of relying completely on the natural inductive coupling, a designer can force the coupling by adding electrical/metal connections, such as vias, between the oscillators.
Thus, arranging multiple oscillators as described above achieves several desirable results, (a) the oscillators become naturally phase-locked to each other; (b) the oscillators have lower power consumption, (c) the oscillators have reduced phase noise; and (d) the oscillators do not take up much more area than just a single oscillator.
Although the present invention has been described in considerable detail with reference to certain preferred versions thereof, other versions are possible. For example, at high frequencies it is important to avoid transmission imperfections that lead to reflections. One kind of imperfection occurs at right angle corners of a metal run that changes direction. At these corners the width of the metal run is greater by √{square root over (2)}, which changes the impedance of the metal run. A better way to change direction is to convert the right angle into a rounded corner or to make two 45-degree turns. Yet another way is to remove a portion of the metal run at the corner so that the distance is the same as the rest of the run. In
Number | Name | Date | Kind |
---|---|---|---|
4686407 | Ceperley | Aug 1987 | A |
4749963 | Makimoto et al. | Jun 1988 | A |
5302920 | Bitting | Apr 1994 | A |
5584067 | Buer et al. | Dec 1996 | A |
5592126 | Boudewijns et al. | Jan 1997 | A |
5652549 | Unterricker et al. | Jul 1997 | A |
5825211 | Smith et al. | Oct 1998 | A |
6002274 | Smith et al. | Dec 1999 | A |
6150886 | Shimomura | Nov 2000 | A |
6157037 | Danielson | Dec 2000 | A |
6259747 | Gustafsson et al. | Jul 2001 | B1 |
6281759 | Coffey | Aug 2001 | B1 |
6323737 | Broekaert | Nov 2001 | B1 |
6396359 | Hajimiri et al. | May 2002 | B1 |
6426662 | Arcus | Jul 2002 | B1 |
6525618 | Wood | Feb 2003 | B2 |
6556089 | Wood | Apr 2003 | B2 |
6566968 | Afghahi | May 2003 | B2 |
6781424 | Lee et al. | Aug 2004 | B2 |
6856208 | Lee et al. | Feb 2005 | B2 |
6870431 | Afghahi | Mar 2005 | B2 |
6900699 | Kim | May 2005 | B1 |
6943599 | Ngo | Sep 2005 | B2 |
6995620 | Afghahi | Feb 2006 | B2 |
7005930 | Kim et al. | Feb 2006 | B1 |
7085668 | Johnson | Aug 2006 | B2 |
7088154 | Ngo | Aug 2006 | B2 |
7091802 | Ham et al. | Aug 2006 | B2 |
7130604 | Wong et al. | Oct 2006 | B1 |
7218180 | Wood | May 2007 | B2 |
7224199 | Kang | May 2007 | B1 |
7224235 | De Ranter et al. | May 2007 | B2 |
7236060 | Wood | Jun 2007 | B2 |
7242272 | Ham et al. | Jul 2007 | B2 |
7274262 | Ham et al. | Sep 2007 | B2 |
7295076 | Kim et al. | Nov 2007 | B2 |
7307483 | Tzartzanis et al. | Dec 2007 | B2 |
7315219 | Chiang | Jan 2008 | B2 |
7339439 | Roubadia et al. | Mar 2008 | B2 |
7378893 | Kang | May 2008 | B1 |
7397230 | Tabaian et al. | Jul 2008 | B2 |
7409012 | Martin et al. | Aug 2008 | B2 |
7446578 | Huang | Nov 2008 | B2 |
7471153 | Kee et al. | Dec 2008 | B2 |
7482884 | Wang et al. | Jan 2009 | B2 |
7504895 | Neidorff | Mar 2009 | B2 |
7511588 | Gabara | Mar 2009 | B2 |
7513873 | Shifrin | Apr 2009 | B2 |
7515005 | Dan | Apr 2009 | B2 |
7541794 | Tabaian et al. | Jun 2009 | B2 |
7551038 | Jang et al. | Jun 2009 | B2 |
7571337 | Zhai et al. | Aug 2009 | B1 |
7577225 | Azadet et al. | Aug 2009 | B2 |
7609756 | Wood | Oct 2009 | B2 |
7612621 | Kim et al. | Nov 2009 | B2 |
7616070 | Tzartzanis et al. | Nov 2009 | B2 |
7656239 | Bietti et al. | Feb 2010 | B2 |
7656336 | Wood | Feb 2010 | B2 |
7656979 | Leydier et al. | Feb 2010 | B2 |
7663328 | Gonder | Feb 2010 | B2 |
7715143 | Bliss et al. | May 2010 | B2 |
7741921 | Ismailov | Jun 2010 | B2 |
7782988 | Ziesler | Aug 2010 | B2 |
7833158 | Bartz | Nov 2010 | B2 |
7847643 | Da Dalt | Dec 2010 | B2 |
7885625 | Muhammad et al. | Feb 2011 | B2 |
7893778 | Mohtashemi et al. | Feb 2011 | B2 |
7907023 | Liang et al. | Mar 2011 | B2 |
7911284 | Kuwano | Mar 2011 | B2 |
7924076 | Suzuki et al. | Apr 2011 | B2 |
7936193 | Van Der Wel et al. | May 2011 | B2 |
7944316 | Watanabe et al. | May 2011 | B2 |
7952439 | Heggemeier et al. | May 2011 | B1 |
7973609 | Ohara et al. | Jul 2011 | B2 |
7995364 | Shiu | Aug 2011 | B2 |
8008981 | Hong et al. | Aug 2011 | B2 |
8049563 | Aoki et al. | Nov 2011 | B2 |
8089322 | Beccue et al. | Jan 2012 | B2 |
20020196089 | Wood | Dec 2002 | A1 |
20030006851 | Wood | Jan 2003 | A1 |
20040240126 | Tiemeijer | Dec 2004 | A1 |
20050068116 | Ham et al. | Mar 2005 | A1 |
20050068146 | Jessie | Mar 2005 | A1 |
20050156680 | Wood | Jul 2005 | A1 |
20060208776 | Tonietto et al. | Sep 2006 | A1 |
20080074202 | Gabara | Mar 2008 | A1 |
20090322394 | Song et al. | Dec 2009 | A1 |
20100117744 | Takinami et al. | May 2010 | A1 |
20100156549 | Uemura et al. | Jun 2010 | A1 |
20100321121 | Mohtashemi | Dec 2010 | A1 |
20110095833 | Mohtashemi et al. | Apr 2011 | A1 |
20110156760 | Bhuiyan et al. | Jun 2011 | A1 |
20110156773 | Beccue | Jun 2011 | A1 |
20110195683 | Brekelmans et al. | Aug 2011 | A1 |
20110286510 | Levantino et al. | Nov 2011 | A1 |
20120008717 | van Sinderen et al. | Jan 2012 | A1 |
20120013363 | Takinami et al. | Jan 2012 | A1 |
20120013407 | Takinami et al. | Jan 2012 | A1 |
20120025918 | Wang et al. | Feb 2012 | A1 |
Number | Date | Country |
---|---|---|
0696843 | Feb 1996 | EP |
2 349 524 | Nov 2000 | GB |
WO 0167603 | Sep 2001 | WO |
WO 2009-140585 | Nov 2009 | WO |
Entry |
---|
Wood et al., Rotary Traveling-Wave Oscillator Arrays: A New Clock Technology, IEEE Journal of Solid-State Circuits, Nov. 2001, vol. 36, No. 11, pp. 1654-1665. |
Le Grand de Mercey, 18GHz Rotary Traveling Wave Voltage Conrolle Oscillator in a CMOS Technology PhD Thesis, Universtat der Bundeswehr Munchen, Aug. 3, 2004. |
Jun-Chau and Liang-Hung Lu, A 32-GHz Rotary Traveling-Wave Voltage Controlled Oscillator in 0.18-um CMOS, IEEE Microwave and Wireless Components Letters, Oct. 2007, vol. 17, No. 10, pp. 724-726. |
International Preliminary Report on Patentability and Written Opinion of the International Searching Authority in PCT application No. PCT/US2009/044114, dated Jan. 14, 2010. |
Detcheverry et al., The effect of copper design rules on inductor performance, Phillips Research Laboratories, Sep. 16, 2003. |
Kleveland, et al., 50 GHz Interconnect Design in Standard Silicon Technology, Center For Integrated Systems, Standford University, Stanford, CA, 1998 IEEE MSS-S Digest. |
Kleveland et al., Line Inductance Extraction and Modeling in a Real Chip with a Power Grid, Center for Integrated Systems, Standford University, Stanford, CA, 1999 IEEE. |
Kral et al., RF-CMOS Oscillators with Switched Tuning, IEEE 1998 Custom Integrated Circuits Conference. |
Lee et al., A 40Gb/s Clock and Data Recovery Circuit in 0.18 um CMOS Technology, 2003 IEEE International Solid-State Circuits Conference. |
Reatti, et al., Solid and Litz-Wire Winding Non-linear Resistance Comparision, Proc. 43rd IEEE Midwest Sump. On Circuits and Systems, Lansing, MI, Aug. 8, 2000 IEEE. |
Integrated CMOS Transmit-Receive Switch Using On-Chip Spiral Inductors, Phd dissertation, Stanford University, Talwalkar, Dec. 2003. |
Modeling and Design of Planar Integrated Magnetic Components, MSEE dissertation, Wang, Shen Virginia Polytechnic Institute, Jul. 21, 2003. |
Yabuki et al., Miniature Stripline Dual-mod Ring Resonators and Their Application to Oscillating Devices, 1995 IEEE MSS-S Digest, 1995 IEEE. |
On-chip Spiral Inductors with Patterned Ground Shields for Si-Based RF IC's, Cetner For Integrated Systems, Stanford University, Stanford, CA. IEEE Journal of Solid State Circuits, vol. 33, No. 5, May 1998. |
International Search Report and Written Opinion of the International Searching Authority in PCT application No. PCT/US2012/068016, dated Mar. 11, 2013, 9 pages. |
Number | Date | Country | |
---|---|---|---|
20120319783 A1 | Dec 2012 | US |
Number | Date | Country | |
---|---|---|---|
61053637 | May 2008 | US |
Number | Date | Country | |
---|---|---|---|
Parent | 12465890 | May 2009 | US |
Child | 13341995 | US |