MILLIMETER-WAVE PHASE-LOCKED LOOP WITH INJECTION-LOCKED FREQUENCY DIVIDER USING QUARTER-WAVELENGTH TRANSMISSION LINE AND METHOD OF CALIBRATION

• US 20090042528A1
• Filed: 08/07/2007
• Published: 02/12/2009
• Est. Priority Date: 08/07/2007
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Intel Corporation
• Inventors: Pellerano, Stefano, Mukhopadhyay, Rajarshi, Palaskas, Georgios
• Granted Patent: US 7,856,212 B2
• Time in Patent Office: Days
• US Class Current: 455/260
• CPC Class Codes: H03L 2207/06 Phase locked loops with a controlled oscillator having at least two frequency control terminals
• CPC Class Codes: H03L 7/095 using a lock detector H03L7/087 takes precedence
• CPC Class Codes: H03L 7/18 using a frequency divider or counter in the loop H03L7/20, H03L7/22 take precedence
• CPC Class Codes: H03L 7/193 the frequency divider/counter comprising a commutable pre-divider, e.g. a two modulus divider

Abstract

Embodiments of a millimeter-wave phase-locked loop with an injection-locked frequency divider (ILFD) are generally described herein. Other embodiments may be described and claimed. In some embodiments, the ILFD uses a quarter-wavelength transmission line. A method of calibrating an ILFD is also provided to allow the ILFD to operate at or near the center of its locking range for each of a plurality of VCO oscillating frequency bands.

Claims

1. A millimeter-wave phase-locked loop (PLL) comprising:

an injection-locked frequency divider (ILFD) to generate a divided output frequency from an injected millimeter-wave frequency;

calibration circuitry to determine values for an ILFD control signal to be applied to the ILFD for a selected oscillating frequency band to cause the ILFD to operate at or near a center of a locking range of the ILFD; and

a voltage controlled oscillator (VCO) to generate the injected millimeter-wave frequency as an output frequency of the PLL based at least in part on the divided output frequency generated by the ILFD.

2. The millimeter-wave PLL of claim 1 wherein the ILFD comprises:

a pseudo-differential pair of transistors;

a quarter-wavelength transmission line coupled between the pseudo-differential pair and ground to receive the injected millimeter-wave frequency; and

a pair of transistors operating as voltage controlled resistors responsive to the ILFD control signal.

3. The millimeter-wave PLL of claim 2 wherein the quarter-wavelength transmission line provides a high impedance at a millimeter-wave frequency and a short-to-ground at DC for the pseudo-differential pair.

4. The millimeter-wave PLL of claim 2 further comprising a look-up table (LUT) to store the values for the ILFD control signal for each of a plurality of selectable VCO oscillating frequency bands,

wherein each value of the ILFD control signal when applied to the ILFD causes the ILFD to operate at or near the center of the locking range for an associated one of the selectable VCO oscillating frequency bands.

5. The millimeter-wave PLL of claim 4 wherein the calibration circuitry is configured to perform a calibration procedure for the PLL,

wherein as part of the calibration procedure, the calibration circuitry is configured to:

measure a further divided down output frequency for different settings of the ILFD control signal when applied to the ILFD for a selected VCO oscillating frequency band to identify the locking range for the ILFD; and

select a value for the ILFD control signal for the selected VCO oscillating frequency band that causes the ILFD to operate at or near the center of the locking range,

wherein the further divided down output frequency is generated by a second divider stage that divides the divided output frequency provided by the ILFD by an integer value.

6. The millimeter-wave PLL of claim 5 wherein during the calibration procedure, the calibration circuitry further:

repeats the measuring of the further divided down output frequency for the different settings of the ILFD control signal to identify the locking range for the ILFD for each of a plurality of VCO oscillating frequency bands; and

stores the selected value for the ILFD control signal in the LUT for each of the plurality of VCO oscillating frequency bands,

wherein the selected values for the ILFD control signal allows the ILFD to operate at or near the center of the locking range for the plurality of VCO oscillating frequencies, and

wherein during the calibration procedure, the calibration circuitry sets a VCO control voltage to a predetermined value to disable a phase/frequency detector and charge pump of the PLL.

7. The millimeter-wave PLL of claim 5 wherein the calibration procedure is performed each time the PLL is powered up.

8. The millimeter-wave PLL of claim 1 wherein the ILFD is a first divider stage of the PLL, and

wherein the millimeter-wave PLL further comprises a second divider stage to divide the divided output frequency of the ILFD by an integer value to provide a further divided down output frequency for comparison with a reference frequency for use in generating a VCO control voltage for controlling the VCO.

9. The millimeter-wave PLL of claim 2 wherein the ILFD comprises first and second stages in a ring-oscillator configuration, each stage to receive in-phase versions of the injected millimeter-wave frequency,

wherein each stage comprises a pseudo-differential pair of transistors, a quarter-wavelength transmission line coupled between the pseudo-differential pair and ground to receive the injected millimeter-wave frequency, and a pair of transistors operating as voltage controlled resistors responsive to the ILFD control signal, and

wherein each stage is responsive to the ILFD control signal to cause the ILFD to operate at or near the center of the locking range.

10. An injection-locked frequency divider (ILFD) to generate a divided output frequency from an injected millimeter-wave frequency comprising:

a pseudo-differential pair of transistors;

a quarter-wavelength transmission line coupled between the pseudo-differential pair and ground to receive the injected millimeter-wave frequency; and

a pair of transistors operating as voltage-controlled resistors responsive to an ILFD control signal selected to cause the ILFD to operate at or near a center of a locking range of the ILFD.

11. The ILFD of claim 10 wherein the quarter-wavelength transmission line provides a high impedance at a millimeter-wave frequency and a short-to-ground at DC for the pseudo-differential pair of transistors to help maximize current through the pseudo-differential pair providing for a wider output signal swing.

12. The ILFD of claim 11 wherein the ILFD comprises first and second stages in a ring-oscillator configuration, each stage to receive in-phase versions of the injected millimeter-wave frequency,

wherein each stage comprises a pseudo-differential pair of transistors, a quarter-wavelength transmission line coupled between the pseudo-differential pair and ground to receive the injected millimeter-wave frequency, and a pair of transistors operating as voltage controlled resistors responsive to an ILFD control signal selected to cause the ILFD to operate at or near a center of the locking range, and

wherein each stage is responsive to the ILFD control signal to cause the ILFD to operate at or near the center of the locking range.

13. The ILFD of claim 10 further comprising a cross-coupled pair of transistors to latch an output of the ILFD.

14. A method of calibrating an injection-locked frequency divider (ILFD) comprising:

measuring a further divided down output frequency for different settings of an ILFD control signal when applied to the ILFD for a selected VCO oscillating frequency band to identify a locking range for the ILFD; and

selecting a value for the ILFD control signal for the selected VCO oscillating frequency band that causes the ILFD to operate at or near a center of the locking range.

15. The method of claim 14 further comprising:

generating, with the ILFD, a divided output frequency from an injected millimeter-wave frequency;

determining values for an ILFD control signal to be applied to the ILFD for a selected VCO oscillating frequency band to cause the ILFD to operate at or near the center of the locking range; and

generating, with a voltage controlled oscillator (VCO), the injected millimeter-wave output frequency as an output signal of a phase-locked loop (PLL) based at least in part on the divided output frequency generated by the ILFD.

16. The method of claim 14 comprising:

repeating the measuring of the further divided down output frequency for the different settings of the ILFD control signal to identify a locking range for each of the selected VCO oscillating frequency bands; and

storing the selected value for the ILFD control signal in the LUT for each of the VCO oscillating frequency bands,

wherein the selected values for the ILFD control signal allows the ILFD to operate at or near the center of the locking range for the VCO oscillating frequency bands, and

wherein during the measuring, a VCO control voltage is set to a predetermined value to disable a phase/frequency detector and charge pump.

17. The method of claim 15 comprising performing at least the measuring and selecting at powered up.

18. A wireless communication device comprising front-end circuitry for communicating millimeter-wave signals, wherein the front-end circuitry comprises a millimeter-wave phase-locked loop (PLL) for use in generating the millimeter-wave signals, and wherein the millimeter-wave PLL comprises:

an injection-locked frequency divider (ILFD) to generate a divided output frequency from an injected millimeter-wave frequency;

calibration circuitry to determine values for an ILFD control signal to be applied to the ILFD for a selected VCO oscillating frequency band to cause the ILFD to operate at or near a center of a locking range of the ILFD; and

a voltage controlled oscillator (VCO) to generate the injected millimeter-wave frequency as an output frequency of the PLL based at least in part on the divided output frequency generated by the ILFD.

19. The wireless communication device of claim 18 wherein the ILFD comprises:

a pseudo-differential pair of transistors;

a quarter-wavelength transmission line coupled between the pseudo-differential pair and ground to receive the injected millimeter-wave frequency; and

a pair of transistors operating as voltage controlled resistors responsive to the ILFD control signal.

20. The wireless communication device of claim 19 wherein the quarter-wavelength transmission line provides a high impedance at a millimeter-wave frequency and a short-to-ground at DC for the pseudo-differential pair.

21. The wireless communication device of claim 18, wherein the PLL further comprises a look-up table (LUT) to store the values for the ILFD control signal for each of a plurality of selectable VCO oscillating frequency bands,

wherein each value of the ILFD control signal when applied to the ILFD causes the ILFD to operate at or near the center of the locking range for an associated one of the selectable VCO oscillating frequency bands.

22. The wireless communication device of claim 21 wherein the calibration circuitry is configured to perform a calibration procedure for the PLL,

wherein as part of the calibration procedure, the calibration circuitry is configured to:

measure a further divided down output frequency for different settings of the ILFD control signal when applied to the ILFD for the selected VCO oscillating frequency band to identify the locking range for the ILFD; and

select a value for the ILFD control signal for the selected VCO oscillating frequency band that causes the ILFD to operate at or near the center of the locking range,

wherein the further divided down output frequency is generated by a second divider stage that divides the ILFD output frequency by an integer value.

23. The wireless communication device of claim 22 wherein during the calibration procedure, the calibration circuitry further:

repeats the measuring of the further divided down output frequency for the different settings of the ILFD control signal to identify the locking range for the ILFD for each of a plurality of VCO oscillating frequency bands; and

stores the selected value for the ILFD control signal in the LUT for each of the plurality of VCO oscillating frequency bands,

wherein the selected values for the ILFD control signal allows the ILFD to operate at or near the center of the locking range for the plurality of VCO oscillating frequencies, and

wherein during the calibration procedure, the calibration circuitry sets a VCO control voltage to a predetermined value to disable a phase/frequency detector and charge pump of the PLL.