Apparatus and methods for frequency tuning of rotary traveling wave oscillators

Patent metadata

Field	Value
Publication number	US-10277233-B2
Application number	US-201615288313-A
Country	US
Kind code	B2
Filing date	Oct 7, 2016
Priority date	Oct 7, 2016
Publication date	Apr 30, 2019
Grant date	Apr 30, 2019

Abstract

Apparatus and methods for frequency tuning of rotary traveling wave oscillators (RTWOs) are provided herein. In certain configurations, distributed quantized tuning is used to tune a frequency of the RTWO. The RTWO includes a plurality of segments distributed around the RTWO's ring, and the segments include tuning capacitors and other circuitry. The distributed quantized frequency tuning is used to control the tuning capacitors in the RTWO's segments using separately controllable code values, thereby enhancing the RTWO's frequency step size or resolution. Moreover, in configurations including multiple RTWO rings that are locked to one another to reduce phase noise, the distributed quantized frequency tuning can be used to separately set the tuning capacitors across multiple RTWO rings that are coupled to one another.

First claim

What is claimed is:

1. A rotary traveling wave oscillator (RTWO) comprising:
a first RTWO ring;
a plurality of segments positioned around the first RTWO ring and including a first segment and a second segment;
a plurality of tuning capacitors that are selectable to control an oscillation frequency of the RTWO and including a first plurality of capacitors in the first segment and a second plurality of capacitors in the second segment; and
segmented decoder circuitry positioned around the first RTWO ring, the segmented decoder circuitry operable to control selection of the plurality of tuning capacitors based on one or more frequency tuning codes wherein the segmented decoder circuitry includes a first decoder of the first segment configured to control selection of the first plurality of capacitors based on decoding a first input code, and a second decoder of the second segment configured to control selection of the second plurality of capacitors based on decoding a second input code that is separately controllable from the first input code.

2. The RTWO of claim 1 , wherein the segmented decoder circuitry comprises a plurality of local decoders each configured to control a number of selected capacitors for a corresponding one of the plurality of segments, and a plurality of tuning decoders configured to control the plurality of local decoders based on the one or more frequency tuning codes.

3. The RTWO of claim 2 , wherein the one or more frequency tuning codes comprises a fine frequency tuning code, wherein the segmented decoder circuitry is implemented such that a selection of one or more tuning decoders in response to a given value of the fine frequency tuning code is dynamically chosen.

4. The RTWO of claim 3 , wherein the segmented decoder circuitry is implemented such that a sequence of selecting each of the plurality of tuning decoders is different for a first ramp of the fine frequency tuning code relative to a second ramp of the fine frequency tuning code.

5. The RTWO of claim 4 , wherein the sequence of selecting rotates through a plurality of different selection sequences.

6. The RTWO of claim 4 , wherein the sequence of selecting is chosen randomly or pseudo-randomly.

7. The RTWO of claim 1 , wherein the segmented decoder circuitry is implemented such that a selection of one or more tuning capacitors in response to a given value of the one or more frequency tuning codes is dynamically chosen.

8. The RTWO of claim 1 , where the first RTWO ring comprises a plurality of sides, wherein the segmented decoder circuitry is further configured to balance a number of selected tuning capacitors for each side of the RTWO ring.

9. The RTWO of claim 8 , wherein the decoder circuitry is implemented such that the number of selected tuning capacitors per side of the RTWO ring is at most one tuning capacitor apart for each value of the one or more frequency tuning codes.

10. The RTWO of claim 1 , further comprising a second RTWO ring in phase lock with the first RTWO ring, wherein the segmented decoder circuitry separately controls a number of selected capacitors of the first RTWO ring and the second RTWO ring.

11. The RTWO of claim 10 , wherein the segmented decoder circuitry is further configured to balance a number of selected tuning capacitors for the first RTWO ring and the second RTWO ring.

12. The RTWO of claim 11 , wherein the segmented decoder circuitry is implemented such that a number of selected tuning capacitors per RTWO ring is at most one tuning capacitor apart for each value of the one or more frequency tuning codes.

13. The RTWO of claim 1 , wherein the plurality of tuning capacitors comprises a plurality of fine tuning capacitors and at least one of a plurality of coarse tuning capacitors or a plurality of process, voltage, and temperature (PVT) tuning capacitors, wherein the first plurality of capacitors controlled by the first decoder are fine tuning capacitors, and wherein the second plurality of capacitors controlled by the second decoder are fine tuning capacitors.

14. The RTWO of claim 1 , wherein the one or more frequency tuning codes comprises a fine frequency tuning code, wherein the segmented decoder circuitry is further configured to receive an offset code operable to provide a capacitance adjustment to a particular segment of the plurality of segments by adjusting a value of the fine frequency tuning code.

15. The RTWO of claim 14 , wherein the offset code is configured to provide a dynamic capacitance adjustment to the plurality of segments while the RTWO is operational to linearize the RTWO.

16. A rotary traveling wave oscillator (RTWO) comprising:
a first RTWO ring;
a plurality of segments positioned around the first RTWO ring, each segment of the plurality of segments comprising a plurality of fine tuning capacitors that are selectable to control an oscillation frequency of the RTWO; and
segmented decoder circuitry comprising a plurality of local decoders positioned around the first RTWO ring and including at least four local decoders for fine tuning, wherein each respective local decoder of the plurality of local decoders is configured to receive a respective fine integer tuning code for a respective segment of the plurality of segments to control the fine tuning capacitors in the respective segment, wherein the four local decoders receive separately controllable fine integer tuning codes.

17. The RTWO of claim 16 , wherein the segmented decoder circuitry further comprises respective tuning decoders configured to control the respective fine integer tuning codes based on one or more frequency tuning codes.

18. The RTWO of claim 17 , wherein the one or more frequency tuning codes comprises a fine frequency tuning code, wherein the segmented decoder circuitry is implemented such that a selection of one or more tuning decoders in response to a given value of the fine frequency tuning code is dynamically chosen.

19. The RTWO of claim 17 , wherein the one or more frequency tuning codes comprises a fine frequency tuning code, wherein the segmented decoder circuitry is further configured to receive an offset code operable to provide a capacitance adjustment to a particular segment of the plurality of segments by adjusting a value of the fine frequency tuning code.

20. The RTWO of claim 16 , further comprising a second RTWO ring in phase lock with the first RTWO ring, wherein the segmented decoder circuitry separately controls a number of selected capacitors of the first RTWO ring and the second RTWO ring.

Assignees

• Analog Devices Inc

Inventors

• Shanan Hyman

Classifications

• H03L2207/50

  All digital phase-locked loop · CPC title

• H03B2201/0208

  the means being an element with a variable capacitance, e.g. capacitance diode · CPC title

• H03B2200/0016

  including a ring, disk or loop shaped resonator · CPC title

• H03B5/1841

  the frequency-determining element being a strip line resonator (H03B5/1805, H03B5/1817, H03B5/1864 and H03B5/1882 take precedence) · CPC title

• H03L7/0995 Primary

  the oscillator comprising a ring oscillator · CPC title