RADAR TRANSCEIVER WITH PHASE NOISE CANCELLATION

• US 20180113193A1
• Filed: 10/06/2017
• Published: 04/26/2018
• Est. Priority Date: 10/24/2016
• Status: Active Grant

• Current Assignee: Infineon Technologies AG
• Original Assignee: Infineon Technologies AG
• Inventors: HUEMER, Mario, MELZER, Alexander, ONIC, Alexander, STUHLBERGER, Rainer
• Granted Patent: US 10,663,559 B2
• Time in Patent Office: Days
• CPC Class Codes: G01S 13/34 using transmission of continuous, frequency-modulated waves while heterodyning the received signal, or a signal derived therefrom, with a locally-generated signal related to the contemporaneously transmitted signal
• CPC Class Codes: G01S 13/343 using sawtooth modulation
• CPC Class Codes: G01S 13/931 of land vehicles
• CPC Class Codes: G01S 7/028 Miniaturisation, e.g. surface mounted device [SMD] packaging or housings
• CPC Class Codes: G01S 7/038 Feedthrough nulling circuits
• CPC Class Codes: G01S 7/2813 Means providing a modification of the radiation pattern for cancelling noise, clutter or interfering signals, e.g. side lobe suppression, side lobe blanking, null-steering arrays specially adapted to secondary radar systems G01S13/762; aerials or aerials systems H01Q21/29, H01Q25/00
• CPC Class Codes: G01S 7/35 Details of non-pulse systems
• CPC Class Codes: G01S 7/4056 specially adapted to FMCW
• CPC Class Codes: G01S 7/406 using internally generated reference signals, e.g. via delay line, via RF or IF signal injection or via integrated reference reflector or transponder
• CPC Class Codes: G01S 7/4065 involving a delay line
• CPC Class Codes: H03B 1/04 Reducing undesired oscillations, e.g. harmonics
• CPC Class Codes: H03B 2202/073 by modifying the internal feedback of the oscillator

Abstract

A method for cancelling phase noise in a radar signal is described herein. In accordance with one embodiment, the method includes transmitting an RF oscillator signal, which represents a local oscillator signal including phase noise, to a radar channel and receiving a respective first RF radar signal from the radar channel. The first RF radar signal included at least one radar echo of the transmitted RF oscillator signal. Further, the method includes applying the RF oscillator signal to an artificial radar target composed of circuitry, which applies a delay and a gain to the RF oscillator signal, to generate a second RF radar signal. The second RF radar signal is modulated by a modulation signal thus generating a frequency-shifted RF radar signal. Further, the method includes subtracting the frequency-shifted RF radar signal from the first RF radar signal.

Claims

1. A method for cancelling phase noise in a radar signal, the method comprising:

transmitting a radio frequency (RF) oscillator signal, which represents a local oscillator signal including phase noise, to a radar channel;

receiving a respective first RF radar signal from the radar channel, the first RF radar signal including at least one radar echo of the transmitted RF oscillator signal;

applying the RF oscillator signal to an artificial radar target composed of circuitry, which applies a delay and a gain to the RF oscillator signal, to generate a second RF radar signal;

modulating the second RF radar signal by a modulation signal to generate a frequency-shifted RF radar signal; and

subtracting the frequency-shifted RF radar signal from the first RF radar signal.

2. The method according to claim 1,

wherein one radar echo of the at least one radar echo is a short-range (SR) leakage signal caused by a SR target.

3. The method according to claim 1,

wherein the phase noise included in the RF oscillator signal is also present in the first RF radar signal as well as in the second RF radar signal.

4. The method according to claim 1,

wherein a first radar echo of the at least one radar echo is a short-range (SR) leakage signal caused by a SR target, the first radar echo being characterized by a round-trip delay time (RTDT), wherein the delay of the artificial radar target is significantly lower than the RTDT of the first radar echo.

5. The method according to claim 4,

wherein the phase noise included in the RF oscillator signal is introduced into the first RF radar signal by the first radar echo.

6. The method according to claim 5,

wherein the phase noise introduced into the first RF radar signal by the first radar echo is approximated by a phase noise included in the second RF radar signal amplified by a noise gain.

7. The method according to claim 6,

wherein the modulation signal has an amplitude which is set dependent on the noise gain.

8. The method according to claim 6,

wherein the noise gain is set based on the delay of the artificial radar target, the RTDT of the first radar echo and a power spectrum density of the phase noise included in the RF oscillator signal.

9. The method according to claim 4,

wherein the modulation signal has a modulation frequency that depends on the RTDT of the first radar echo and the delay of the artificial radar target.

10. The method according to claim 4,

wherein the modulation signal has a modulation frequency that is proportional to a difference between the RTDT of the first radar echo and the delay of the artificial radar target.

11. The method according to claim 1, further comprising:

down-converting a third RF radar signal that results from subtracting the frequency-shifted RF radar signal from the first RF radar signal into a base-band to generate a base-band radar signal which includes at least one beat frequency corresponding to the at least one radar echo.

12. The method according to claim 11, further comprising:

high-pass filtering the base-band radar signal to remove at least one of the at least one one beat frequency from the base-band radar signal which is caused by a SR target, and/or

low-pass filtering the base-band radar signal to remove undesired image frequencies caused by the down-conversion.

13. The method according to claim 12,

wherein the high-pass filtering is accomplished before or after the low-pass filtering, or

wherein the high-pass filtering and the low-pass filtering are accomplished by a band-pass filter.

14. A radar transceiver, comprising:

a local oscillator (LO) operably generating a radio frequency (RF) oscillator signal, which includes phase noise;

at least one transmit antenna coupled to the LO for transmitting the RF oscillator signal to a radar channel;

at least one receive antenna for receiving a first RF radar signal from the radar channel, the first RF radar signal including at least one radar echo of the transmitted RF oscillator signal;

an artificial radar target coupled to the LO to receive the RF oscillator signal, and composed of circuitry, which applies a delay and a gain to the RF oscillator signal, to generate a second RF radar signal;

a modulator coupled to the artificial radar target to receive the second RF radar signal, and configured to modulate the second RF radar signal with a modulation signal to generate a frequency-shifted RF radar signal; and

an RF subtractor circuit coupled to the at least one receive antenna and the and configured to subtract the frequency-shifted RF radar signal from the first RF radar signal.

15. The radar transceiver according to claim 14,

wherein the at least one transmit antenna and the at least one receive antenna are identical in a monostatic radar configuration.

16. The radar transceiver according to claim 14, further comprising:

a first RF amplifier coupled between the LO and the at least one transmit antenna for amplifying the RF oscillator signal.

17. The radar transceiver according to claim 16, further comprising:

a second RF amplifier coupled to the at least one receive antenna for amplifying the first RF radar signal.

18. The radar transceiver according to claim 17,

wherein the second RF amplifier is coupled to the at least one receive antenna downstream of the RF subtractor circuit.

19. The radar transceiver according to claim 14,

wherein the modulator is an I/Q-modulator that includes a first mixer and a second mixer to generate an in-phase signal and a quadrature signal, respectively, and further includes a hybrid coupler configured to combine the in-phase signal and the quadrature signal to generate the frequency-shifted RF radar signal.

20. The radar transceiver according to claim 19,

wherein the I/Q-modulator includes a further hybrid coupler configured to direct the modulation signal to both, the first mixer and the second mixer.

21. The radar transceiver according to claim 14,

wherein a first radar echo of the at least one radar echo is a short-range (SR) leakage signal caused by a SR target, the first radar echo being characterized by a round-trip delay time (RTDT), wherein the delay of the artificial radar target is significantly lower than the RTDT of the first radar echo.

22. The radar transceiver according to claim 21, further comprising:

an oscillator configured to generate the modulation signal for the modulator with a frequency that depends on the delay of the artificial radar target and the RTDT of the first radar echo.

23. The radar transceiver according to claim 14, further comprising:

a mixer coupled to the RF subtractor circuit and configured to down-convert, into a base-band, an output signal of the RF subtractor circuit representing a difference between the first RF radar signal and the frequency-shifted RF radar signal.

24. The radar transceiver according to claim 23, further comprising:

a base band signal processing chain coupled to the mixer downstream thereof, the base band signal processing chain including at least one of;

a high-pass filter, or a low-pass filter.

25. The radar transceiver according to claim 14,

wherein the LO, the modulator, and the artificial radar target are integrated in a single monolithic microwave integrated circuit (MMIC).