Electronic Devices Having Spatial Ranging Calibration Capabilities

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.

What is claimed is: 
     
         1 . Wireless circuitry comprising:
 one or more antennas;   a transmitter configured to transmit, using the one or more antennas, a radio-frequency signal having a first tone and a second tone separated from the first tone by a frequency gap; and   a mixer configured to receive, using the one or more antennas, the radio-frequency signal transmitted by the transmitter, the mixer being configured to generate a baseband signal based on the radio-frequency signal transmitted by the transmitter and the radio-frequency signal received using the one or more antennas.   
     
     
         2 . The wireless circuitry of  claim 1 , wherein the mixer is configured to generate the baseband signal by mixing the radio-frequency signal transmitted by the transmitter with the radio-frequency signal received using the one or more antennas. 
     
     
         3 . The wireless circuitry of  claim 2 , further comprising:
 a signal path that couples the transmitter to the mixer, the mixer being configured to receive, over the signal path, the radio-frequency signal transmitted by the transmitter.   
     
     
         4 . The wireless circuitry of  claim 1 , wherein the transmitter is configured to transmit, using the one or more antennas, a radar signal based on the baseband signal. 
     
     
         5 . The wireless circuitry of  claim 4 , wherein the transmitter is configured to distort the radar signal based on the baseband signal. 
     
     
         6 . The wireless circuitry of  claim 5 , further comprising:
 measurement circuitry configured to generate phase and magnitude information based on the baseband signal, the transmitter being configured to distort the radar signal based on the phase and magnitude information.   
     
     
         7 . The wireless circuitry of  claim 1 , wherein the mixer comprises an in-phase and quadrature-phase (I/Q) mixer. 
     
     
         8 . The wireless circuitry of  claim 1 , wherein the frequency gap is less than or equal to 20 MHz. 
     
     
         9 . The wireless circuitry of  claim 1 , wherein the baseband signal is separated from a direct current (DC) frequency by the frequency gap. 
     
     
         10 . The wireless circuitry of  claim 1 , wherein the transmitter comprises:
 a signal generator configured to generate the first tone and the second tone;   a digital-to-analog converter configured to convert the first tone and the second tone to an analog domain; and   an additional mixer configured to upconvert the first tone and the second tone to radio frequencies.   
     
     
         11 . A method of operating radar circuitry, the method comprising:
 transmitting, using a transmit chain, a radio-frequency signal that includes a first tone and a second tone separated from the first tone by a frequency gap;   receiving, using a receive chain and one or more antennas, the radio-frequency signal transmitted using the transmit chain;   receiving, at a mixer in the receive chain, the radio-frequency signal over a signal path between the transmit chain and the receive chain; and   generating, using the mixer, a baseband signal based on the radio-frequency as received using the one or more antennas and the radio-frequency signal as received over the signal path.   
     
     
         12 . The method of  claim 11 , wherein generating the baseband signal comprises mixing the radio-frequency signal as received using the one or more antennas with the radio-frequency signal as received over the signal path. 
     
     
         13 . The method of  claim 11 , wherein the baseband signal is offset from a direct current frequency by the frequency offset. 
     
     
         14 . The method of  claim 13 , wherein the frequency offset is less than or equal to 20 MHz. 
     
     
         15 . The method of  claim 11 , further comprising:
 transmitting, using the transmit chain, a radar waveform based on the baseband signal.   
     
     
         16 . The method of  claim 15 , wherein transmitting the radar waveform comprises distorting the radar waveform based on the baseband signal. 
     
     
         17 . The method of  claim 15 , wherein the signal path comprises a de-chirp path, the mixer includes a de-chirp mixer, and the radar waveform comprises a frequency ramp. 
     
     
         18 . An electronic device comprising:
 one or more antennas;   radar circuitry configured to generate first signals that are transmitted and received using the one or more antennas and second signals that are that are transmitted and received using the one or more antennas, the first signals including a first tone and a second tone separated from the first tone by a frequency gap; and   one or more processors configured to detect an external object based on the second signals.   
     
     
         19 . The electronic device of  claim 18 , the radar circuitry being configured to distort the second signals based on the first signals. 
     
     
         20 . The electronic device of  claim 19 , the one or more processors being configured to estimate a power droop of the radar circuitry based on the first signals and the radar circuitry being configured to distort the second signals based on the estimated power droop.