Transmit power reduction for radio frequency transmitters

Patent metadata

Field	Value
Publication number	US-12392865-B2
Application number	US-202117547907-A
Country	US
Kind code	B2
Filing date	Dec 10, 2021
Priority date	Dec 10, 2021
Publication date	Aug 19, 2025
Grant date	Aug 19, 2025

Abstract

A method of operating a monolithic microwave integrated circuit (MMIC) in a radar transmitter includes: sending a radio frequency (RF) signal to a power amplifier of the radar transmitter, where the power amplifier is controlled by a termination control signal, where when the termination control signal is de-asserted, the power amplifier is configured to pass the RF signal through the power amplifier for transmission by an RF antenna, where when the termination control signal is asserted, the power amplifier is configured to terminate the RF signal in the power amplifier; transmitting the RF signal by de-asserting the termination control signal; and after de-asserting the termination control signal, disabling transmission of the RF signal by: reducing a power of the RF signal; and asserting the termination control signal.

First claim

What is claimed is:

1. A method of operating a radar transmitter, the method comprising:
supplying a first radio frequency (RF) signal to a phase shifter, wherein the phase shifter comprises an in-phase (I) component RF path and a quadrature (Q) component RF path, wherein the I-component RF path and the Q-component RF path are configured to generate a phase shift to the first RF signal according to a first scale factor of the I-component RF path and a second scale factor of the Q-component RF path, wherein the phase shifter is configured to generate a second RF signal at an output terminal of the phase shifter, wherein the output terminal of the phase shifter is coupled to an input terminal of a power amplifier of the radar transmitter;
generating an enable signal for the power amplifier, wherein the enable signal is a binary digital control signal that alternates between a first value and a second value during operation of the radar transmitter;
passing the second RF signal from the phase shifter through the power amplifier by setting the enable signal for the power amplifier to the first value;
after passing the second RF signal, setting the enable signal for the power amplifier to the second value to reduce a gain of the power amplifier; and
based on setting the enable signal to the second value, reducing a power of the second RF signal by setting the first scale factor of the I-component RF path and the second scale factor of the Q-component RF path.

2. The method of claim 1 , wherein a power consumption of the power amplifier remains substantially the same regardless of whether the enable signal has the first value or the second value.

3. The method of claim 1 , wherein the first RF signal comprises a plurality of frames, wherein each frame of the first RF signal comprises:
a chirp signal having a frequency that changes from a first frequency value to a second frequency value during a first period of the frame; and
a fly-back signal having a frequency that changes from the second frequency value to the first frequency value within a fly-back period of the frame, wherein the enable signal for the power amplifier has the second value at least partially during the fly-back period.

4. The method of claim 1 , wherein the phase shifter is configured to generate the second RF signal by:
modulating an in-phase carrier signal with a first data signal using a first modulator, wherein the first data signal is determined by the first scale factor of the I-component RF path;
modulating a quadrature carrier signal with a second data signal using a second modulator, wherein the second data signal is determined by the second scale factor of the Q-component RF path, wherein the first data signal and the second data signal are selected to provide a first phase shift; and
adding a first output of the first modulator with a second output of the second modulator to generate the second RF signal.

5. The method of claim 4 , wherein reducing the power of the second RF signal comprises:
decreasing the first scale factor of the I-component RF path; and
decreasing the second scale factor of the Q-component RF path.

6. The method of claim 5 , wherein each of the first scale factor and the second scale factor is decreased to zero in one or more steps.

7. The method of claim 6 , wherein the first scale factor and the second scale factor change values at a same time.

8. The method of claim 1 , wherein the enable signal starts changing from the first value to the second value at a first time instant, wherein the first scale factor and the second scale factor start to decrease from non-zero values to zero at or before the first time instant.

9. The method of claim 8 , wherein the enable signal starts changing from the second value to the first value at a second time instant, wherein the method further comprises:
after the first scale factor and the second scale factor are decreased to zero, starting changing the first scale factor and the second scale factor from zero to the non-zero values at or after the second time instant.

10. The method of claim 9 , wherein the first scale factor and the second scale factor change from zero to the non-zero values in one or more steps.

11. The method of claim 1 , wherein the power amplifier comprises a switch coupled between the input terminal of the power amplifier and an output terminal of the power amplifier, wherein the output terminal of the power amplifier is connected to an RF antenna, wherein setting the enable signal for the power amplifier to the second value opens the switch.

12. The method of claim 1 , wherein reducing the power of the second RF signal comprises reducing the power of the second RF signal from a non-zero value to zero in multiple steps within a period of time, wherein the period of time starts at a first time instant and ends at a second time instant, wherein setting the enable signal for the power amplifier to the second value comprises starting changing the enable signal for the power amplifier from the first value to the second value at the second time instant.

13. A method of operating a monolithic microwave integrated circuit (MMIC) in a radar transmitter, the method comprising:
sending a radio frequency (RF) signal to an input terminal of a power amplifier of the radar transmitter, wherein the RF signal is generated by modulating an in-phase carrier with an in-phase data signal and modulating a quadrature carrier with a quadrature data signal, wherein the power amplifier is controlled by a termination control signal, wherein the termination control signal is a binary control signal, wherein when the termination control signal is de-asserted, the power amplifier is configured to pass the RF signal through the power amplifier for transmission by an RF antenna by closing a switch of the power amplifier coupled between the input terminal of the power amplifier and the RF antenna, wherein when the termination control signal is asserted, the power amplifier is configured to terminate the RF signal in the power amplifier by opening the switch;
transmitting the RF signal by de-asserting the termination control signal; and
after de-asserting the termination control signal, disabling transmission of the RF signal by:
reducing a power of the RF signal, wherein reducing the power of the RF signal comprises reducing a first amplitude of the in-phase data signal and reducing a second amplitude of the quadrature data signal; and
asserting the termination control signal.

14. The method of claim 13 , wherein before reducing the power of the RF signal, the first amplitude of the in-phase data signal has a first value, and the second amplitude of the quadrature data signal has a second value, wherein reducing the power of the RF signal comprises reducing the first amplitude from the first value to zero and reducing the second amplitude from the second value to zero.

15. The method of claim 14 , wherein reducing the first amplitude comprises starting, at a first time instant, reducing the first amplitude from the first value to zero in a plurality of steps, wherein reducing the second amplitude comprises starting, at the first time instant, reducing the second amplitude from the second value to zero in a plurality of steps, wherein the termination control signal is asserted at a second time instant after the first time instant.

16. The method of claim 14 , further comprising, after disabling transmission of the RF signal, resuming transmission of the RF signal by:
increasing the power of the RF signal by increasing the first amplitude from zero to a third valu

Assignees

• Infineon Technologies Ag

Inventors

• Knapp Herbert
• Li Hao

Classifications

• G01S7/358

  using I/Q processing · CPC title

• H03F2200/451

  the amplifier being a radio frequency amplifier · CPC title

• G01S13/325

  using transmission of coded signals, e.g. P.S.K. signals · CPC title

• H03F3/245 Primary

  with semiconductor devices only · CPC title

• G01S7/35 Primary

  Details of non-pulse systems · CPC title