Steerable transmit, steerable receive frequency modulated continuous wave radar transceiver

• US 9,285,461 B2
• Filed: 03/12/2013
• Issued: 03/15/2016
• Est. Priority Date: 03/12/2013
• Status: Active Grant

• Current Assignee: Nokia Technologies Oy (Nokia Corporation)
• Original Assignee: Nokia Technologies Oy (Nokia Corporation)
• Inventors: Swirhun, Paul Stanley, Townley, Andrew Patrick
• Primary Examiner(s): Sotomayor, John B
• Assistant Examiner(s): Windrich, Marcus
• Application Number:
  US13/795,544
• Publication Number:
  US 20140266866A1
• Time in Patent Office: 1,099 Days
• Field of Search: 342/175, 342/188, 342/194, 34235775-35777
• US Class Current: 1/1
• 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 2013/0254 Active array antenna
• CPC Class Codes: G01S 7/026 involving the transmission of elliptically or circularly polarised waves
• CPC Class Codes: G01S 7/03 Details of HF subsystems specially adapted therefor, e.g. common to transmitter and receiver
• CPC Class Codes: G01S 7/35 Details of non-pulse systems
• CPC Class Codes: H01P 5/187 Broadside coupled lines

Abstract

Apparatus, method, and system example embodiments provide an improved integrated circuit RF front end to simultaneously transmit and receive signals for radar imaging. In an example embodiment, an apparatus comprises a transceiver coupled to a circularly polarized antenna assembly, capable of transmitting circularly polarized signals that are a component of a multi-signal radar beam; a power amplifier configured to amplify a transmit signal, coupled through isolation couplers to the circularly polarized antenna assembly; a phase shifting block circuit configured to perform phase shifting of a local oscillator signal, in response to the receipt of phase control signals, to perform phased-array beam steering of the multi-signal radar beam when the component circular signals are associated with signals transmitted from other transceivers receiving the phase control signals. The apparatus further includes a receiver circuit utilizing a receive phase-shifting circuit coupled to a quadrature down-conversion mixer, for receive beam steering.

Claims

1. An apparatus, comprising:

a transceiver coupled to a dual-orthogonally polarized antenna assembly, capable of transmitting circularly polarized signals that are a component of a multi-element radar beam;

a transmit phase shifting circuit in the transceiver, configured to apply a phase shift to a transmit signal from a local oscillator, in response to receiving transmit phase control signals;

a power amplifier in the transceiver coupled to the transmit phase shifting circuit, having a differential output with a first port coupled through a first isolation coupler to a first polarity terminal of the dual-orthogonally polarized antenna assembly, for transmission of in-phase signals and with a second port of the differential output coupled through a second isolation coupler and a 90-degree phase delay to a second polarity terminal of the dual-orthogonally polarized antenna assembly, for transmission of quadrature-phase signals, the in-phase and quadrature-phase signals at the antenna assembly terminals forming a circularly polarized electromagnetic wave that is additively combined with circularly polarized electromagnetic waves transmitted from other transceivers, to perform phased-array beam steering of the multi-element radar beam in response to the transmit phase control signals;

a power combining circuit in the transceiver, with a first input terminal coupled through the first isolation coupler to the first polarity terminal of the dual-orthogonally polarized antenna assembly and with a second input terminal coupled through the second isolation coupler to the second polarity terminal of the dual-orthogonally polarized antenna assembly, and an output terminal;

a low noise amplifier in the transceiver, with an input terminal coupled to the output terminal of the power combining circuit, and an output terminal, configured to amplify a received circularly-polarized signal;

a first mixer having a first input coupled to the first isolation coupler and a second input coupled to the output of the low noise amplifier, configured to output a difference signal at an output thereof, related to a difference in frequency of transmitted and received radar signals, with the difference signal generated using a signal in-phase with the local oscillator signal;

a second mixer having a first input coupled to the second isolation coupler through a quadrature phase-shifting circuit and a second input coupled to the output of the low noise amplifier, configured to output a difference signal at an output thereof, related to a difference in frequency of transmitted and received radar signals, with the difference signal generated using a signal in quadrature with the local oscillator signal;

a first variable-gain amplifier coupled to the first mixer, configured to amplify in-phase receive signals in response to a first weighted value of the receive phase control signals;

a second variable-gain amplifier coupled to the second mixer, configured to amplify quadrature phase of the receive signals in response a second weighted value of the receive phase control signals; and

a signal combining circuit coupled to outputs of the first and second variable gain amplifiers, configured to combine the amplified in-phase receive signals with the amplified quadrature phase of the receive signals, to rotate the phase of the received signal in response to the receive phase control signals, to steer a received multi-signal radar beam composed of signals reflected by an object, which were earlier transmitted from the other transceivers.

2. The apparatus of claim 1, wherein the transceiver is formed on at least one integrated circuit chip.

3. The apparatus of claim 1, further comprising:

wherein the transmit phase shifting circuit includes two variable-gain amplifiers and a power combining structure to amplify in-phase and quadrature transmit signals in weighted combinations to rotate the phase of the transmitted signal in response to the transmit phase control signals.

4. The apparatus of claim 1, further comprising:

wherein the receive phase shifting circuit includes two variable-gain amplifiers and an analog summer, configured to coherently combine received signals in a phased array by weighted combinations of in-phase and quadrature phase down-converted received signals in response to the receive phase control signals.

5. The apparatus of claim 1, further comprising:

wherein the receive phase shifting circuit includes a quadrature generating circuit, two variable-gain tuned amplifiers, and a power combining structure to amplify in-phase and quadrature receive signals in weighted combinations to rotate the phase of the transmitted signal in response to the transmit phase control signals.

6. The apparatus of claim 1, the transmit phase shifting circuit further comprising:

a first variable-gain amplifier configured to amplify in-phase transmit signals in response to a first weighted value of the transmit phase control signals;

a second variable-gain amplifier configured to amplify quadrature phase of the transmit signals in response a second weighted value of the transmit phase control signals; and

a signal combining circuit coupled to outputs of the first and second variable gain amplifiers, configured to combine the amplified in-phase transmit signals with the amplified quadrature phase of the transmit signals, to rotate the phase of the transmitted signal in response to the transmit phase control signals.

7. The apparatus of claim 1, comprising:

wherein the local oscillator is configured to sweep the frequency of the transmit signal about a center frequency and

wherein the first and second mixers are configured to mix a received radar signal at an earlier transmitted sweep frequency, with a currently transmitted radar signal at a current transmitted sweep frequency and provide a beat note frequency of the mixed signals as a measure of a propagation distance to an object that reflected the received radar signal.

8. The apparatus of claim 1, comprising:

wherein the first isolation coupler and the second isolation coupler are at least one of broadside couplers or Lange couplers.

9. A method, comprising:

phase shifting, in a transceiver, a transmit signal from a local oscillator, in response to receiving transmit phase control signals;

amplifying, in the transceiver, the phase shifted transmit signal, with differential output for transmission of in-phase signals via a first polarity terminal of a dual-orthogonally polarized antenna assembly and transmission of quadrature-phase signals via a second polarity terminal of the dual-orthogonally polarized antenna assembly, forming a circularly polarized electromagnetic wave that is additively combined with circularly polarized electromagnetic waves transmitted from other transceivers;

performing, in the transceiver, phased-array transmit beam steering of a multi-element radar beam in response to transmit phase control signals, to steer the multi-element radar beam in response to the transmit phase control signals;

generating a first difference signal related to a difference in frequency of transmitted and received radar signals, using a signal in-phase with the local oscillator signal;

generating a second difference signal related to a difference in frequency of transmitted and received radar signals, with the difference signal generated using a signal in quadrature with the local oscillator signal; and

phase shifting the first difference signal and the second phase difference signal, to perform phased-array receive beam steering in response to receiving receive phase control signals, to steer received radar signals reflected by an object, which were earlier transmitted from the other transceivers.

10. The method of claim 9, the phase shifting the transmit signal further comprising:

amplifying in-phase transmit signals in response to a first weighted value of the transmit phase control signals;

amplifying quadrature phase of the transmit signals in response a second weighted value of the transmit phase control signals; and

combining the amplified in-phase transmit signals with the amplified quadrature phase of the transmit signals, to rotate the phase of the transmitted signal in response to the transmit phase control signals.

11. The method of claim 9, the phase shifting to perform receive beam steering further comprising:

amplifying in-phase receive signals in response to a first weighted value of the receive phase control signals;

amplifying quadrature phase of the receive signals in response a second weighted value of the receive phase control signals; and

combining the amplified in-phase receive signals with the amplified quadrature phase of the receive signals, to rotate the phase of the received signal in response to the receive phase control signals.