Calibrating an injection locked oscillator

Patent metadata

Field	Value
Publication number	US-10855296-B2
Application number	US-201916585689-A
Country	US
Kind code	B2
Filing date	Sep 27, 2019
Priority date	Sep 27, 2018
Publication date	Dec 1, 2020
Grant date	Dec 1, 2020

Abstract

A circuit for calibrating an injection locked oscillator is provided. The injection locked oscillator includes an injection locking input, an LC tank and an oscillator output to output an oscillator output signal. The circuit is configured to adjust a capacitance of the LC tank to different values, detect an amplitude of the oscillator output signal for each value of the different values of the capacitance while an input signal having a target frequency is applied to the injection locking input, determine a maximum amplitude of the detected amplitudes, and select a value for operating the injection locked oscillator based on the determined maximum amplitude.

First claim

What is claimed is:

1. A circuit configured to calibrate an injection locked oscillator, the injection locked oscillator comprising an injection locking input, an LC tank, and an oscillator output configured to output an oscillator output signal, the circuit configured to:
adjust a capacitance of the LC tank to different values while the injection locked oscillator is turned on;
while the injection locked oscillator is turned on, detect an amplitude of the oscillator output signal for each value of the different values of the capacitance while an input signal having a target frequency is applied to the injection locking input;
determine a maximum amplitude based on the detected amplitudes; and
select a value for operating the injection locked oscillator based on the determined maximum amplitude.

2. The circuit of claim 1 , wherein the circuit is configured to determine a value associated with the maximum amplitude and to select the value associated with the maximum amplitude as the value for operating the injection locked oscillator.

3. The circuit of claim 1 , further comprising:
a peak detector configured to detect the amplitude of the oscillator output signal for each value of the different values of the capacitance.

4. The circuit of claim 3 , wherein the peak detector is directly coupled to the oscillator output for receiving the oscillator output signal.

5. The circuit of claim 1 , wherein the circuit is configured to apply different digital control words to a capacitor bank of the LC tank to adjust the capacitance of the LC tank to the different values.

6. The circuit of claim 1 , wherein the circuit is configured to adjust the capacitance of the LC tank to the different values resulting in a resonance frequency of the LC tank in a frequency range of ±15% of the target frequency.

7. The circuit of claim 1 , wherein the injection locked oscillator comprises cross-coupled transistors that enable an oscillator function of the injection locked oscillator, wherein the cross-coupled transistors are turned on while the injection locked oscillator is turned on such that the oscillator function is enabled.

8. An injection locked oscillator circuit, comprising:
an injection locked oscillator configured to receive an input signal having a target frequency at an injection locking input thereof, the injection locked oscillator comprising an LC tank having an adjustable capacitance, a control input configured to receive a control signal to adjust the capacitance of the LC tank, and an oscillator output configured to output an oscillator output signal; and
a circuit configured to calibrate the injection locked oscillator while the injection locked oscillator is turned on, wherein the circuit is configured to:
adjust a capacitance of the LC tank to different values while the injection locked oscillator is turned on,
while the injection locked oscillator is turned on, detect an amplitude of the oscillator output signal for each value of the different values of the capacitance while an input signal having a target frequency is applied to the injection locking input,
determine a maximum amplitude of the detected amplitudes, and
select a value for operating the injection locked oscillator based on the determined maximum amplitude, and

wherein the circuit is coupled to the oscillator output and the control input of the injection locked oscillator, and is configured to apply a control signal corresponding to the selected value to the control input in a normal operation of the injection locked oscillator.

9. The injection locked oscillator circuit of claim 8 , wherein the injection locked oscillator comprises cross-coupled transistors that enable an oscillator function of the injection locked oscillator, wherein the cross-coupled transistors are turned on while the injection locked oscillator is turned on such that the oscillator function is enabled.

10. The injection locked oscillator circuit of claim 8 , where the circuit includes a peak detector configured to detect the amplitude of the oscillator output signal for each value of the different values of the capacitance while the input signal having the target frequency is applied to the injection locking input, wherein the peak detector is directly coupled to the oscillator output for receiving the oscillator output signal.

11. A frequency multiplier, comprising:
a local oscillator (LO) configured to output a LO signal having a LO frequency;
a harmonic generator coupled to the local oscillator to receive the LO signal and configured to generate at an output thereof a generator output signal at a frequency which is a multiple of the LO frequency; and
an injection locked oscillator comprising:
an injection locked oscillator configured to receive an input signal having a target frequency at an injection locking input thereof, the injection locked oscillator comprising an LC tank having an adjustable capacitance, a control input configured to receive a control signal to adjust the capacitance of the LC tank, and an oscillator output configured to output an oscillator output signal; and
a circuit configured to calibrate the injection locked oscillator while the injection locked oscillator is turned on, wherein the circuit is configured to:
adjust a capacitance of the LC tank to different values while the injection locked oscillator is turned on,
while the injection locked oscillator is turned on, detect an amplitude of the oscillator output signal for each value of the different values of the capacitance while an input signal having a target frequency is applied to the injection locking input,
determine a maximum amplitude of the detected amplitudes, and
select a value for operating the injection locked oscillator based on the determined maximum amplitude,
wherein the circuit is coupled to the oscillator output and the control input of the injection locked oscillator, and is configured to apply a control signal corresponding to the selected value to the control input in a normal operation of the injection locked oscillator, and

wherein the injection locked oscillator is coupled to the harmonic generator to receive the generator output signal at the injection locking input thereof.

12. The frequency multiplier of claim 11 , wherein the injection locked oscillator comprises cross-coupled transistors that enable an oscillator function of the injection locked oscillator, wherein the cross-coupled transistors are turned on while the injection locked oscillator is turned on such that the oscillator function is enabled.

13. The frequency multiplier of claim 11 , where the circuit includes a peak detector configured to detect the amplitude of the oscillator output signal for each value of the different values of the capacitance while the input signal having the target frequency is applied to the injection locking input, wherein the peak detector is directly coupled to the oscillator output for receiving the oscillator output signal.

14. A frequency divider, comprising:
a local oscillator (LO) configured to output a LO signal having a LO frequency;
a divider circuit coupled to the local oscillator to receive the LO signal and configured to generate at an output thereof a divider circuit output signal at a frequency that is a fraction of the LO frequency;
an injection locked oscillator circuit comprising:
an injection locked oscillator configured to receive an input signal having a target frequency at an injection locking input thereof, the injection locked oscillator comprising an LC tank having an adjustable capacitance, a control input configured to receive a control signal to adjust the

Assignees

• Infineon Technologies Ag

Inventors

• Bassi Matteo
• Boi Giovanni
• Cherniak Dmytro
• Padovan Fabio

Classifications

• H03B5/1265 Primary

  switched capacitors · CPC title

• H03J5/246

  using electronic means (H03J5/244 takes precedence) · CPC title

• H03J2200/09

  Calibration of oscillator in receiver, using an external carrier frequency as reference · CPC title

• H03L7/18

  using a frequency divider or counter in the loop (H03L7/20, H03L7/22 take precedence) · CPC title

• H03B5/1215

  the current source or degeneration circuit being in common to both transistors of the pair, e.g. a cross-coupled long-tailed pair · CPC title