BANDWIDTH ADJUSTMENT IN A PHASE-LOCKED LOOP OF A LOCAL OSCILLATOR

• US 20190319582A1
• Filed: 04/08/2019
• Published: 10/17/2019
• Est. Priority Date: 04/17/2018
• Status: Active Grant

• Current Assignee: Infineon Technologies AG
• Original Assignee: Infineon Technologies AG
• Inventors: HESCHL, Lukas, Stuhlberger, Rainer
• Granted Patent: US 10,763,783 B2
• Time in Patent Office: Days
• CPC Class Codes: H03B 2201/0266 the means comprising a transistor
• CPC Class Codes: H03B 5/1243 the means comprising voltage variable capacitance diodes
• CPC Class Codes: H03B 5/1265 switched capacitors
• CPC Class Codes: H03L 2207/06 Phase locked loops with a controlled oscillator having at least two frequency control terminals
• CPC Class Codes: H03L 7/0805 the loop being adapted to provide an additional control signal for use outside the loop
• CPC Class Codes: H03L 7/0893 the up-down pulses controlling at least two source current generators or at least two sink current generators connected to different points in the loop
• CPC Class Codes: H03L 7/0898 the source or sink current values being variable H03L7/0896 takes precedence
• CPC Class Codes: H03L 7/099 concerning mainly the controlled oscillator of the loop
• CPC Class Codes: H03L 7/0996 Selecting a signal among the plurality of phase-shifted signals produced by the ring oscillator
• CPC Class Codes: H03L 7/189 comprising a D/A converter for generating a coarse tuning voltage
• CPC Class Codes: H03L 7/1976 using a phase accumulator for controlling the counter or frequency divider

Abstract

A method for a radar device is described. According to one example implementation, the method comprises generating an RF signal using a voltage-controlled oscillator (VCO), wherein the frequency of the RF signal depends on a first tuning voltage and a second tuning voltage. The method also comprises setting the second tuning voltage using a phase-locked loop coupled to the VCO, with the result that the frequency of the RF signal corresponds to a desired frequency. The first tuning voltage is changed in such a manner that the second tuning voltage set by the phase-locked loop corresponds approximately to a predefined value. Another example implementation relates to a method for a radar device comprising: generating an RF signal using a VCO, wherein the frequency of the RF signal depends on a tuning voltage, setting the tuning voltage using a phase-locked loop coupled to the VCO, with the result that the frequency of the RF signal corresponds to a desired frequency, and determining a differential VCO gain of the VCO. The bandwidth of the phase-locked loop is set on the basis of the determined VCO gain.

Claims

1. A method comprising:

generating a radio-frequency (RF) signal using a voltage-controlled oscillator (VCO), wherein a frequency of the RF signal depends on a first tuning voltage and a second tuning voltage,

setting the second tuning voltage using a phase-locked loop coupled to the VCO to cause the frequency of the RF signal to correspond to a particular frequency,

changing the first tuning voltage in such a manner that the second tuning voltage set by the phase-locked loop corresponds approximately to a predefined value,

determining a differential VCO gain of the VCO for one or more values of the frequency of the RF signal, and

adjusting a bandwidth of the phase-locked loop based on the differential VCO gain by setting an absolute value of an output current of a charge pump contained in the phase-locked loop.

2. The method as claimed in claim 1,

wherein changing the first tuning voltage comprises varying the first tuning voltage according to an iteration scheme.

3. The method as claimed in claim 1,

wherein, after the first tuning voltage has been changed, the second tuning voltage is regulated using the phase-locked loop in such a manner that the frequency of the RF signal is adjusted to the particular frequency.

4. The method as claimed in claim 1, further comprising:

generating a chirp by changing the particular frequency, which results in a corresponding change in the second tuning voltage using the phase-locked loop.

5. The method as claimed in claim 4,

wherein the first tuning voltage remains constant during the generation of the chirp.

7. The method as claimed in claim 1, further comprising:

changing the particular frequency by a defined frequency difference, while the first tuning voltage remains the same,

measuring a resulting change in the second tuning voltage, and

adjusting a bandwidth of the phase-locked loop based on the defined frequency difference and the resulting change in the second tuning voltage.

6. (canceled)

8. (canceled)

9. A method comprising:

generating a radio-frequency (RF) signal using a voltage-controlled oscillator (VCO), wherein a frequency of the RF signal depends on a tuning voltage,

setting the tuning voltage using a phase-locked loop coupled to the VCO to cause the frequency of the RF signal to correspond to a particular frequency,

determining a differential VCO gain of the VCO by;

changing the particular frequency, starting from a first frequency, by a defined frequency difference,

measuring a resulting change in the tuning voltage, and

determining the differential VCO gain based on the resulting change in the tuning voltage and the defined frequency difference, and

setting a bandwidth of the phase-locked loop based on the differential VCO gain by setting an absolute value of an output current of a charge pump combined in the phase-locked loop.

10. (canceled)

11. (canceled)

12. A radio-frequency (RF) oscillator circuit comprising:

a voltage-controlled oscillator (VCO) which is configured to generate an RF signal, wherein a frequency of the RF signal depends on a first tuning voltage and a second tuning voltage,

a phase-locked loop to which the VCO is coupled and which is configured to set the second tuning voltage in such a manner that the frequency of the RF signal corresponds to a particular frequency, and

a control circuit which is configured to set the first tuning voltage in such a manner that the second tuning voltage set by the phase-locked loop corresponds approximately to a predefined value,

wherein the control circuit is configured to change the particular frequency by a determined frequency difference while the first tuning voltage remains the same and to determine a resulting change in the second tuning voltage, and

wherein the control circuit is also configured to generate a control signal for the phase-locked loop based on the change in the second tuning voltage and the defined frequency difference, wherein a bandwidth of the phase-locked loop depends on the control signal, and wherein the phase-locked loop has a charge pump and the control signal is used to determine an absolute value of an output current of the charge pump.

13. The RF oscillator circuit as claimed in claim 12, further comprising:

a digital-to-analog converter which is configured to receive a digital signal from the control circuit and to generate a corresponding analog signal which determines the first tuning voltage.

14. The RF oscillator circuit as claimed in claim 12,

wherein, in order to set the first tuning voltage, the control circuit is configured to iteratively change the first tuning voltage until the second tuning voltage corresponds approximately to the predefined value.

15. The RF oscillator circuit as claimed in claim 12,

wherein, in order to generate a chirp, the control circuit is configured to set and change the particular frequency in accordance with predefined parameter.

18. The RF oscillator circuit as claimed in claim 12,

wherein the control circuit is configured to determine a VCO gain based on a frequency difference and the resulting change in the second tuning voltage and to adjust the bandwidth of the phase-locked loop based on the VCO gain.

16. (canceled)

17. (canceled)

19. A radio-frequency (RF) oscillator circuit comprising:

a voltage-controlled oscillator (VCO) which is configured to generate an RF signal, wherein a frequency of the RF signal depends on a tuning voltage,

a phase-locked loop to which the VCO is coupled and which is configured to set the tuning voltage in such a manner that the frequency of an RF signal corresponds to a particular frequency, and

a control circuit which is coupled to the phase-locked loop and is configured to determine a differential VCO gain of the VCO and to set a bandwidth of the phase-locked loop based on the differential VCO gain.

20. The RF oscillator circuit as claimed in claim 19,

wherein the control circuit is configured, starting from a first frequency, to change the particular frequency by a defined frequency difference and to determine a resulting change in the tuning voltage and to determine the differential VCO gain for the first frequency based on the resulting change and the defined frequency difference.

21. The RF oscillator circuit as claimed in claim 19,

wherein the phase-locked loop has a charge pump having an output current with a settable absolute value, and

wherein the control circuit is configured to change the absolute value of the output current of the charge pump in order to set the bandwidth of the phase-locked loop.