EP-4737935-A1 - DISTRIBUTED COHERENT RADAR SYSTEMS WITH DIGITALLY CONTROLLED LOCAL OSCILLATORS

EP4737935A1EP 4737935 A1EP4737935 A1EP 4737935A1EP-4737935-A1

Abstract

Aspects of this disclosure are directed to various circuit topologies for mitigating coupling. In some embodiments, an amplifier circuit is provided that includes a first amplifier path, a second amplifier path, and a capacitor. The first amplifier path may include a first input, a first transistor, and a first wire coupled between the first input and a first terminal of the first transistor. The second amplifier path may include a second input, a second transistor, and a second wire coupled between the second input and a first terminal of the second transistor. The capacitor may include a first terminal coupled to the first input and a second terminal coupled to the second input. Under such an arrangement, the capacitor may be configured to compensate for a coupling between the first wire and the second wire. Other embodiments are disclosed.

Inventors

LOK, PIETER
WICHERN, ANDREAS HANS WALTER
Jansen, Feike Guus
Freidl, Philipp Franz
MIDDELINK, Marc Klein
BEKOOIJ, MARCO JAN GERRIT

Assignees

NXP B.V.

Dates

Publication Date: 20260506
Application Date: 20241029

Claims (15)

A radar unit for use in a distributed coherent, DCR, automotive radar system, the radar unit comprising: a local clock circuit, comprising: an oscillator; and a digital turning circuit in parallel with the oscillator and comprising a plurality of switchable capacitors; a tuning controller configured to adjust an operating frequency of the local clock circuit, by controlling the plurality of switchable capacitors within a non-transmit period of operation of the radar unit; and a communication unit configured to transmit and receive data from a central processor unit; wherein the tuning controller is configured to adjust the operating frequency of the local clock circuit, in response to the communication unit receiving a frequency offset data from the central processor unit, to reduce a frequency difference between operating frequency of the local clock circuit and a remote clock circuit of the DCR automotive radar system.
The radar unit according to claim 1, wherein the communication unit is further configured to transmit an own frequency offset data to the central processor unit.
The radar unit according to claim 1 or 2, wherein the non-transmit period of operation is a period between transmission of successive sequences of chirps.
The radar unit according to any preceding claim, wherein the communication unit is configured to communicate data with the central processor unit by means of an ethernet communication protocol.
The radar unit according to any preceding claim, further configured to determine the own frequency offset by a Precision Time Protocol.
The radar unit according to claim 5, wherein the radar unit is configured to implement the Precision Time Protocol by determining a rate-ratio between the clock circuit and the remote clock circuit.
A distributed coherent radar system for automotive applications, comprising the radar unit as claimed in any preceding claim, being a first radar unit; a further radar unit; and a central processor unit configured to communicate with each of the radar unit and the further radar unit.
The distributed coherent radar system of claim 7, wherein the central processor unit comprises a central processor oscillator, and a central communication unit.
The distributed coherent radar system of claim 8 wherein the central processor unit comprises the remote clock circuit.
The distributed coherent radar system of claim 7 or 8, wherein the further radar unit comprises the remote clock circuit.
The distributed coherent radar system according to claim 10, wherein the further radar unit is a radar unit according to any of claims 1 to 6.
The distributed coherent radar system according to claim 10 or 11, wherein the frequency offset is the difference between own frequency offset of the first radar unit and an own frequency offset of the further radar unit.
The distributed coherent radar system according to claim 12, wherein the first radar unit and the further radar unit are configured to reduce an operating frequency difference therebetween to zero.
The distributed coherent radar system according to claim 13, wherein the own frequency offset of the first radar unit is equal to the own frequency offset of the further radar unit, and each are non-zero.
A method of operating a radar unit in a distributed coherent, DCR, automotive radar system, the radar unit including: a local clock circuit, having an oscillator and a digital turning circuit, in parallel with the oscillator and comprising a plurality of switchable capacitors; a tuning controller configured to adjust an operating frequency of the local clock circuit, by controlling the plurality of switchable capacitors within a non-transmit period of operation of the radar unit; and a communication unit configured to transmit and receive data from a central processor unit; the method comprising: receiving, by the communication unit, a frequency offset data from the central processor unit, in response thereto adjusting, by the tuning controller, the operating frequency of the local clock circuit, thereby reducing a frequency difference between operating frequency of the local clock circuit and a remote clock circuit of the DCR automotive radar system.

Description

FIELD OF THE DISCLOSURE The present disclosure relates to distributed radar systems, and radar units therefor. BACKGROUND A distributed radar is one in which two or more individual units, commonly referred to as radar units or radar heads, are used as part of a single radar. A distributed coherent radar (DCR) system requires synchronization in time, frequency and phase between the individual radar units. Such synchronization is typically achieved or enabled by use of a master clock with a single oscillator, typically provided by a central processor or zonal processor unit, to each of the distributed radar units. Alternatively, the master clock may be provided by one of the radar units or heads, with a wired connection to the other radar units to distribute the clock signal. SUMMARY According to a fist aspect of the present disclosure, there is provided a radar unit for use in a distributed coherent, DCR, automotive radar system, the radar unit comprising: a local clock circuit, comprising: an oscillator; and a digital turning circuit in parallel with the oscillator and comprising a plurality of switchable capacitors; a tuning controller configured to adjust an operating frequency of the local clock circuit, by controlling the plurality of switchable capacitors within a non-transmit period of operation of the radar unit; and a communication unit configured to transmit and receive data from a central processor unit; wherein the tuning controller is configured to adjust the operating frequency of the local clock circuit, in response to the communication unit receiving a frequency offset data from the central processor unit, to reduce a frequency difference between operating frequency of the local clock circuit and a remote clock circuit of the DCR automotive radar system. A DCR automotive radar system using such a radar unit may be able to operate with a low tolerance oscillator and clock in a zonal or central processor, and may avoid a requirement for direct communication between multiple radar heads. In one or more embodiments, the communication unit is further configured to transmit an own frequency offset data to the central processor unit. The central processor unit may therefore act as a "central clearing house" by collecting the frequency offset data from each of the radar units, and distributing this to each of the other units. In one or more embodiments, the non-transmit period of operation is a period between transmission of successive sequences of chirps. In one or more embodiments the communication unit is configured to communicate data with the central processor unit by means of an ethernet communication protocol. Ethernet communication protocols are widely used, and particularly convenient providing for packet-based communication; however the present disclosure is not limited thereto, and other communication protocols, such as control area networks (CAN) may be used in the alternative In one or more embodiments, the radar unit may be further configured to determine the own frequency offset by a Precision Time Protocol. In one or more such embodiments, the radar unit may be configured to implement the Precision Time Protocol by determining a rate-ratio between the clock circuit and the remote clock circuit. According to a second aspect of the present disclosure, there is provided a distributed coherent radar system for automotive applications, comprising a radar unit as described above; a further radar unit; and a central processor unit configured to communicate with each of the radar unit and the further radar unit. According to such an aspect, a direct link between the radar unit and the further radar unit may not be necessary. And, moreover, it may be possible to use local clocks in each of the radar units and still provide a distributed coherent radar system. The system may include two or more radar units. In one or more embodiments, the central processor unit comprises a central processor oscillator, and a central communication unit. In some embodiments, the central processor oscillator is part of a clock circuit, and may have a lower precision (that is to say a wider range of possible values for any given nominal value) than the oscillators of the radar units. In one or more such embodiments, the central processor unit comprises the remote clock circuit. In one or more other embodiments, the further radar unit comprises the remote clock circuit. In one or more such embodiments, the further radar unit is a radar unit such as has been described above. That is to say, the radar units or radar heads may all be similar and in such embodiments it may not be necessary to include a leader radar head and follow-up radar heads. In one or more embodiments, the frequency offset is the difference between own frequency offset of the radar unit and an own frequency offset of the further radar unit. In one or more embodiments, the first radar unit and the further radar unit are configured to reduce an opera