# US 10,312,922 B2 · Apparatus and methods for rotary traveling wave oscillators > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,312,922 B2 - Document ID: US10312922B2 - Status: Granted - Kind: B2 - Application number: 15/288,339 - Filed: 2016-10-07 - Published: 2018-04-12 - Granted: 2019-06-04 - Earliest claimed: 2016-10-07 - Assignees: Analog Devices, Inc. - Applicants: Analog Devices, Inc. - Inventors: Hyman Shanan - Web page: https://patentgrep.com/patent/US10312922B2 ## CPC - H03L 7/0995: {the oscillator comprising a ring oscillator} - H03B 5/1841: {the frequency-determining element being a strip line resonator (H03B5/1805, H03B5/1817, H03B5/1864 and H03B5/1882 take precedence)} - H03B 5/1852: {the semiconductor device being a field-effect device} - G04F 10/005: {Time-to-digital converters [TDC] (analog-to-digital converters with intermediate conversion to time or phase H03M1/50, H03M1/60)} - H03B 2200/0016: including a ring, disk or loop shaped resonator - H03L 2207/50: All digital phase-locked loop - H03L: AUTOMATIC CONTROL, STARTING, SYNCHRONISATION OR STABILISATION OF GENERATORS OF ELECTRONIC OSCILLATIONS OR PULSES (generation of oscillations H03B) - H03B: GENERATION OF OSCILLATIONS, DIRECTLY OR BY FREQUENCY-CHANGING, BY CIRCUITS EMPLOYING ACTIVE ELEMENTS WHICH OPERATE IN A NON-SWITCHING MANNER; GENERATION OF NOISE BY SUCH CIRCUITS (generators adapted for electrophonic musical instruments G10H; masers or lasers H01S; generation of oscillations in plasma H05H) - G04F: TIME-INTERVAL MEASURING (measuring pulse characteristics G01R, e.g. G01R29/02; in radar or like systems G01S) ## Abstract Apparatus and methods for rotary traveling wave oscillators (RTWOs) are provided herein. In certain configurations, an RTWO includes a differential transmission line connected in a ring and a plurality of segments distributed around the ring. The segments include metal stubs extending from the RTWO's differential transmission line. The metal stubs aid in providing access to additional layout resources for tuning capacitors and other circuitry of the RTWO's segments, while permitting the length of RTWO's ring to be relative short. Thus, the metal stubs do not inhibit the RTWO from operating with relatively high oscillation frequency, while providing connectivity to tuning capacitors that tune the RTWO's oscillation frequency over a wide tuning range and/or provide fine frequency step size. ## Claims ### Claim 1 A rotary traveling wave oscillator (RTWO) comprising: an RTWO ring comprising a first transmission line conductor and a second transmission line conductor and configured to carry a traveling wave; and a plurality of segments positioned around the RTWO ring, wherein a first segment of the plurality of segments comprises: a pair of metal stubs comprising a first metal stub electrically connected to the first transmission line conductor and a second metal stub electrically connected to the second transmission line conductor, wherein the pair of metal stubs extend substantially perpendicularly from the RTWO ring such that the pair of metal stubs do not inhibit the RTWO from high frequency oscillation; and one or more capacitor tuning banks electrically connected to the pair of metal stubs and operable to control an oscillation frequency of the RTWO. ### Claim 2 (depends on 1) The RTWO of claim 1, wherein the first segment further comprises a time-to-digital converter (TDC) latch electrically connected between the first metal stub and the second metal stub and operable to detect passage of the traveling wave. ### Claim 3 (depends on 1) The RTWO of claim 1, wherein the first metal stub and the second metal stub have substantially equal length. ### Claim 4 (depends on 1) The RTWO of claim 1, wherein the first metal stub and the second metal stub each have a length of at least a factor of 0.05 of a wavelength of the traveling wave. ### Claim 5 (depends on 1) The RTWO of claim 1, wherein the first metal stub and the second metal stub each have a length of at least about 25 μm. ### Claim 6 (depends on 1) The RTWO of claim 1, wherein the first segment further comprises a first tap buffer including an input electrically connected to the first metal stub, and a second tap buffer including an input electrically connected to the second metal stub. ### Claim 7 (depends on 1) The RTWO of claim 1, wherein the first segment further comprises a regeneration circuit electrically connected between the first metal stub and the second metal stub and configured to provide energy to the traveling wave to compensate for a loss of the first and second transmission line conductors. ### Claim 8 (depends on 1) The RTWO of claim 1, wherein each of the plurality of segments comprises a plurality of tuning capacitor banks operable to provide a least significant bit (LSB) tuning resolution of 50 kHz/LSB or smaller and a tuning range of 4 GHz or greater. ### Claim 9 (depends on 1) The RTWO of claim 1, wherein the one or more capacitor tuning banks comprises a fine tuning capacitor bank electrically connected between the first metal stub and the second metal stub, and a coarse tuning capacitor bank electrically connected between the first metal stub and the second metal stub. ### Claim 10 (depends on 9) The RTWO of claim 9, wherein the one or more capacitor tuning banks further comprises a process, voltage, and temperature (PVT) tuning capacitor bank electrically connected between the first metal stub and the second metal stub. ### Claim 11 (depends on 1) The RTWO of claim 1, wherein each of the segments comprises a TDC latch, wherein the RTWO further comprises a clock distribution tree and a reference clock buffer configured to provide a reference clock signal to the TDC latch of each of the segments via the clock distribution tree. ### Claim 12 A phase-locked loop (PLL) comprising: a PLL core configured to generate one or more frequency tuning codes; and a rotary traveling wave oscillator (RTWO) comprising: a ring comprising a first transmission line conductor and a second transmission line conductor and configured to carry a traveling wave; and a plurality of segments positioned around the ring and each comprising a pair of metal stubs comprising a first metal stub electrically connected to the first transmission line conductor and a second metal stub electrically connected to the second transmission line conductor, wherein the pair of metal stubs extend substantially perpendicularly from the ring such that the pair of metal stubs do not inhibit the RTWO from high frequency oscillation; and one or more capacitor tuning banks electrically connected to the pair of metal stubs and operable to control an oscillation frequency of the RTWO based on the one or more frequency tuning codes. ### Claim 13 (depends on 12) The PLL of claim 12, wherein the first metal stub and the second metal stub each have a length of at least a factor of 0.05 of a wavelength of the traveling wave. ### Claim 14 (depends on 12) The PLL of claim 12, wherein the RTWO is configured to operate in the PLL as both a digitally controlled oscillator and a time to digital converter. ### Claim 15 (depends on 12) The PLL of claim 12, wherein the one or more capacitor tuning banks comprises a fine tuning capacitor bank and a coarse tuning capacitor bank, and wherein the one or more frequency tuning codes comprises a coarse tuning code and a fine integer tuning code. ### Claim 16 (depends on 12) The PLL of claim 12, wherein the first metal stub and the second metal stub have substantially equal length. ### Claim 17 (depends on 12) The PLL of claim 12, wherein the first metal stub and the second metal stub each have a length of at least about 25 μm. ### Claim 18 (depends on 12) The PLL of claim 12, wherein the plurality of segments positioned around the ring each further comprise a regeneration circuit electrically connected between the first metal stub and the second metal stub and configured to provide energy to the traveling wave to compensate for a loss of the first and second transmission line conductors. ### Claim 19 (depends on 12) The PLL of claim 12, wherein each of the plurality of segments comprises a plurality of tuning capacitor banks operable to provide a least significant bit (LSB) tuning resolution of 50 kHz/LSB or smaller and a tuning range of 4 GHz or greater. ### Claim 20 A method comprising: propagating a traveling wave on a rotary traveling wave oscillator (RTWO) ring that includes a first transmission line conductor and a second transmission line conductor; and controlling an oscillation frequency of the RTWO ring using one or more capacitor tuning banks electrically connected to a pair of metal stubs of a first segment, the pair of metal stubs including a first metal stub electrically connected to the first transmission line conductor and a second metal stub electrically connected to the second transmission line conductor, wherein the pair of metal stubs extend substantially perpendicularly from the RTWO ring such that the pair of metal stubs do not inhibit the RTWO from high frequency oscillation. ### Claim 21 (depends on 20) The method of claim 20, further comprising detecting passage of the traveling wave using a time-to-digital converter (TDC) latch in the first segment, the TDC electrically connected between the first metal stub and the second metal stub. ### Claim 22 (depends on 20) The method of claim 20, further comprising providing signal buffering using a first tap buffer coupled to the first metal stub and a second tap buffer coupled to the second metal stub. ### Claim 23 (depends on 20) The method of claim 20, further comprising using a regeneration circuit in the first segment to provide energy to the traveling wave to compensate for a loss of the first and second transmission line conductors, wherein the regeneration circuit electrically connected between the first metal stub and the second metal stub. ### Claim 24 (depends on 20) The method of claim 20, wherein controlling the oscillation frequency includes: switching a fine tuning capacitor bank in the one or more capacitor tuning banks, the fine tuning capacitor bank electrically connected between the first metal stub and the second metal stub; and switching a coarse tuning capacitor bank electrically connected between the first metal stub and the second metal stub. ### Claim 25 (depends on 24) The method of claim 24, wherein the one or more capacitor tuning banks further comprises a process, voltage, and temperature (PVT) tuning capacitor bank electrically connected between the first metal stub and the second metal stub.