Electronic devices having spatial ranging calibration capabilities

Patent metadata

Field	Value
Publication number	US-11828871-B2
Application number	US-202117150974-A
Country	US
Kind code	B2
Filing date	Jan 15, 2021
Priority date	Jan 15, 2021
Publication date	Nov 28, 2023
Grant date	Nov 28, 2023

Abstract

An electronic device may include radar circuitry. Control circuitry may calibrate the radar circuitry using a multi-tone calibration signal. A first mixer may upconvert the calibration signal for transmission by a transmit antenna. A de-chirp mixer may mix the calibration signal output by the first mixer with the calibration signal as received by a receive antenna or loopback path to produce a baseband multi-tone calibration signal. The baseband signal will be offset from DC by the frequency gap. This may prevent DC noise or other system effects from interfering with the calibration signal. The control circuitry may sweep the first mixer over the radio frequencies of operation of the radar circuitry to estimate the power droop and phase shift of the radar circuitry based on baseband calibration signal. Distortion circuitry may distort transmit signals used in spatial ranging operations to invert the estimated power droop and phase shift.

First claim

What is claimed is:

1. Wireless communication circuitry for performing spatial ranging operations on an external object using transmit signals, the wireless communication circuitry comprising:
a digital-to-analog converter (DAC) configured to generate a multi-tone calibration signal having a first tone and a second tone separated from the first tone by a frequency gap;
a first mixer configured to upconvert the multi-tone calibration signal from a first frequency band to a second frequency band;
a second mixer having a first input configured to receive the multi-tone calibration signal in the second frequency band via a signal path from an output of the first mixer, and having a second input configured to receive the multi-tone calibration signal in the second frequency band via intermediate circuitry communicatively coupled between the output of the first mixer and the second input, wherein the second mixer is configured to generate a baseband multi-tone calibration signal;
measurement circuitry configured to measure a magnitude of the baseband multi-tone calibration signal; and
control circuitry configured to
estimate a power droop of the intermediate circuitry based on the magnitude measured by the measurement circuitry and
distort the transmit signals based on the estimated power droop.

2. The wireless communication circuitry of claim 1 wherein the transmit signals comprise chirp signals and the signal path comprises a de-chirp path, the wireless communication circuitry further comprising:
a chirp generator configured to generate the chirp signals for transmission by a transmit antenna, wherein the first mixer is configured to upconvert the chirp signals to the second frequency band, the first input of the second mixer is configured to receive the chirp signals in the second frequency band via the de-chirp path, and the second input is configured to receive a reflected version of the chirp signals via a receive antenna.

3. The wireless communication circuitry of claim 1 , further comprising:
a signal splitter having an input coupled to the output of the first mixer, a first output coupled to the intermediate circuitry, and a second output coupled to the first input of the second mixer over the signal path.

4. The wireless communication circuitry of claim 3 , wherein the intermediate circuitry comprises:
a third mixer communicatively coupled to the first output of the signal splitter and configured to upconvert the multi-tone calibration signal from the second frequency band to a third frequency band; and
a fourth mixer communicatively coupled to the second input and configured to downconvert the multi-tone calibration signal from the third frequency band to the second frequency band.

5. The wireless communication circuitry of claim 4 , wherein the first frequency band comprises a baseband frequency, the second frequency band comprises frequencies greater than the baseband frequency and less than 10 GHz, and the third frequency band comprises frequencies greater than the second frequency band.

6. The wireless communication circuitry of claim 5 , wherein the second frequency band comprises frequencies greater than 20 GHz.

7. The wireless communication circuitry of claim 4 wherein the intermediate circuitry comprises:
a transmit antenna communicatively coupled to an output of the third mixer and configured to transmit the multi-tone calibration signal in the third frequency band; and
a receive antenna communicatively coupled to an input of the fourth mixer and configured to receive the multi-tone calibration signal in the third frequency band transmitted by the transmit antenna.

8. The wireless communication circuitry of claim 4 , wherein the intermediate circuitry comprises a loopback path communicatively coupled between an output of the third mixer and an input of the fourth mixer, the loopback path being configured to convey the multi-tone calibration signal in the third frequency band.

9. The wireless communication circuitry of claim 1 , wherein the wireless communication circuitry comprises digital predistortion circuitry communicatively coupled to an input of the DAC.

10. The wireless communication circuitry of claim 1 , wherein the measurement circuitry is configured to measure a phase of the baseband multi-tone calibration signal, the control circuitry is configured to estimate a phase shift of the intermediate circuitry based on the phase measured by the measurement circuitry, and the control circuitry is configured to distort the transmit signals based on the phase shift estimated by the measurement circuitry.

11. The wireless communication circuitry of claim 1 , wherein the control circuitry is configured to control the first mixer to sweep over a plurality of radio frequencies, the second mixer is configured to generate the baseband multi-tone calibration signal for each of the radio frequencies in the plurality of radio frequencies, the measurement circuitry is configured to measure the magnitude of the baseband multi-tone calibration signal for each of the radio frequencies in the plurality of radio frequencies, and the control circuitry is configured to estimate the power droop of the intermediate circuitry across each of the radio frequencies in the plurality of radio frequencies.

12. The wireless communication circuitry of claim 1 , wherein the baseband multi-tone calibration signal is separated from a direct current (DC) frequency by the frequency gap and the frequency gap is less than or equal to 20 MHz.

13. A method for calibrating radar circuitry, the method comprising:
with a digital-to-analog converter (DAC) in a transmit chain of the radar circuitry, generating a multi-tone calibration signal having a first tone and a second tone separated from the first tone by a frequency gap of less than 20 MHz;
with a first mixer in the transmit chain, upconverting the multi-tone calibration signal from baseband to a first frequency band;
with a second mixer in the transmit chain, upconverting the multi-tone calibration signal from the first frequency band to a second frequency band;
with a third mixer in a receive chain of the radar circuitry, downconverting the multi-tone calibration signal upconverted by the second mixer from the second frequency band to the first frequency band;
with a de-chirp mixer in the receive chain, generating a baseband multi-tone calibration signal by mixing the multi-tone calibration signal upconverted by the first mixer with the multi-tone calibration signal downconverted by the third mixer, the baseband multi-tone calibration signal being separated from a direct current (DC) frequency by the frequency gap;
with control circuitry, estimating a power droop and phase shift of the radar circuitry based on the baseband multi-tone calibration signal generated by the de-chirp mixer; and
with predistortion circuitry in the transmit chain, predistorting chirp signals transmitted over the transmit chain based on the power droop and phase shift estimated by the control circuitry.

14. The method of claim 13 , further comprising:
with the second mixer, sweeping the second frequency band over a plurality of radio frequencies;
with the third mixer, downconverting the multi-tone calibration signal for each of the radio frequencies in the plurality of radio frequencies;
with the de-chirp mixer, generating the baseband multi-tone calibration signal for each of the radio frequencies in the plurality of radio frequencies; and
with the control circuitry, estimating the power droop of the radar circuitry based on the baseband multi-tone calibration signal generated by the de-chirp mixer for e

Assignees

• Apple Inc

Inventors

• Schrattenecker Jochen
• Sogl Bernhard
• Menkhoff Andreas
• Hur Joonhoi
• Pretl Harald
• Mayer Christian
• Langer Andreas
• Vazny Rastislav

Classifications

• G01S7/4056 Primary

  specially adapted to FMCW · CPC title

• G01S7/40 Primary

  Means for monitoring or calibrating · CPC title

• G01S7/4073

  involving an IF signal injection · CPC title

• G01S7/4008 Primary

  of transmitters · CPC title

• G01S13/32

  using transmission of continuous waves, whether amplitude-, frequency-, or phase-modulated, or unmodulated · CPC title