Method for calibrating transmiter-to-receiver relative phase in millimeter wave beamforming system and associated millimeter wave antenna module

1. A method for calibrating a transmitter-to-receiver (T2R) relative phase in millimeter wave (mmWave) beamforming system, comprising:

transmitting a first calibrated signal to a second antenna of the mmWave beamforming system through a first antenna of the mmWave beamforming system according to a first transmitter (TX) input signal;

receiving the first calibrated signal through the second antenna, and obtaining a first loopback receiver (RX) signal according to the first calibrated signal received by the second antenna;

transmitting a second calibrated signal to the first antenna through the second antenna according to a second TX path input signal;

receiving the second calibrated signal through the first antenna, and obtaining a second loopback RX signal according to the second calibrated signal received by the first antenna; and

calibrating the T2R relative phase according to a phase difference between the first and second loopback RX signals.

2. The method of claim 1 , wherein the first calibrated signal is transmitted by a first TX path, the second calibrated signal is transmitted by a second TX path, the second calibrated signal is received by a first RX path, the first calibrated signal is received by a second RX path; the first TX path, the first RX path, the first antenna, the second TX path, the second RX path, and the second antenna are all packaged in a same antenna module (AM).

3. The method of claim 2 , wherein the T2R relative phase comprises a difference between a first phase difference and a second phase difference, the first phase difference is between a phase mismatch of a signal path of the first TX path and a phase mismatch of a signal path of the second TX path, and the second phase difference is between a phase mismatch of a signal path of the first RX path and a phase mismatch of a signal path of the second RX path.

4. The method of claim 2 , wherein the T2R relative phase comprises a sum of a first phase difference and a second phase difference, the first phase difference is between a phase mismatch of a local oscillator (LO) signal path of the first TX path and a phase mismatch of an LO signal path of the second TX path, and the second phase difference is between a phase mismatch of an LO signal path of the first RX path and a phase mismatch of an LO signal path of the second RX path.

5. The method of claim 2 , wherein the T2R relative phase comprises a sum of a first phase difference and a second phase difference, the first phase difference is between an initial phase of an LO signal path of the first TX path and an initial phase of an LO signal path of the second TX path, and the second phase difference is between an initial phase of an LO signal path of the first RX path and an initial phase of an LO signal path of the second RX path.

6. The method of claim 1 , wherein the first calibrated signal is transmitted by a first TX path, the second calibrated signal is transmitted by a second TX path, the second calibrated signal is received by a first RX path, the first calibrated signal is received by a second RX path; the first TX path, the first RX path, and the first antenna are packaged in a first antenna module (AM); and the second TX path, the second RX path, and the second antenna are packaged in a second AM.

7. The method of claim 6 , wherein the T2R relative phase comprises a difference between a first phase difference and a second phase difference, the first phase difference is between a phase mismatch of a signal path of the first TX path and a phase mismatch of a signal path of the second TX path, and the second phase difference is between a phase mismatch of a signal path of the first RX path and a phase mismatch of a signal path of the second RX path.

8. The method of claim 6 , wherein the T2R relative phase comprises a sum of a first phase difference and a second phase difference, the first phase difference is between a phase mismatch of a local oscillator (LO) signal path of the first TX path and a phase mismatch of an LO signal path of the second TX path, and the second phase difference is between a phase mismatch of an LO signal path of the first RX path and a phase mismatch of an LO signal path of the second RX path.

9. The method of claim 6 , wherein the T2R relative phase comprises a sum of a first phase difference and a second phase difference, the first phase difference is between an initial phase of an LO signal path of the first TX path and an initial phase of an LO signal path of the second TX path, and the second phase difference is between an initial phase of an LO signal path of the first RX path and an initial phase of an LO signal path of the second RX path.

10. A millimeter wave (mmWave) antenna module (AM), comprising:

a first mmWave transceiver path, comprising:

a first antenna;

a first transmitter (TX) path, arranged to transmit a first calibrated signal to a second antenna through the first antenna according to a first TX input signal; and

a first receiver (RX) path, arranged to receive a second calibrated signal through the first antenna, and obtain a second loopback RX signal according to the second calibrated signal received by the first antenna;

a second mmWave transceiver path, comprising:

the second antenna;

a second TX path, arranged to transmit the second calibrated signal to the first antenna through the second antenna according to a second TX input signal; and

a second RX path, arranged to receive the first calibrated signal through the second antenna, and obtain a first loopback RX signal according to the first calibrated signal received by the second antenna; and

a calibration engine, arranged to utilize the first and second RX loopback signals to calibrate a transmitter-to-receiver (T2R) relative phase.

11. The mmWave AM of claim 10 , wherein the first TX path, the first RX path, the first antenna, the second TX path, the second RX path, and the second antenna are all packaged in a same AM.

12. The mmWave AM of claim 11 , wherein the T2R relative phase comprises a difference between a first phase difference and a second phase difference, the first phase difference is between a phase mismatch of a signal path of the first TX path and a phase mismatch of a signal path of the second TX path, and the second phase difference is between a phase mismatch of a signal path of the first RX path and a phase mismatch of a signal path of the second RX path.

13. The mmWave AM of claim 11 , wherein the T2R relative phase comprises a sum of a first phase difference and a second phase difference, the first phase difference is between a phase mismatch of a local oscillator (LO) signal path of the first TX path and a phase mismatch of an LO signal path of the second TX path, and the second phase difference is between a phase mismatch of an LO signal path of the first RX path and a phase mismatch of an LO signal path of the second RX path.

14. The mmWave AM of claim 11 , wherein the T2R relative phase comprises a sum of a first phase difference and a second phase difference, the first phase difference is between an initial phase of an LO signal path of the first TX path and an initial phase of an LO signal path of the second TX path, and the second phase difference is between an initial phase of an LO signal path of the first RX path and an initial phase of an LO signal path of the second RX path.

15. The mmWave AM of claim 10 , wherein the first TX path, the first RX path, and the first antenna are packaged in a first AM; and the second TX path, the second RX path, and the second antenna are packaged in a second AM.

16. The mmWave AM of claim 15 , wherein the T2R relative phase comprises a difference between a first phase difference and a second phase difference, the first phase difference is between a phase mismatch of a signal path of the first TX path and a phase mismatch of a signal path of the second TX path, and the second phase difference is between a phase mismatch of a signal path of the first RX path and a phase mismatch of a signal path of the second RX path.

17. The mmWave AM of claim 15 , wherein the T2R relative phase comprises a sum of a first phase difference and a second phase difference, the first phase difference is between a phase mismatch of a local oscillator (LO) signal path of the first TX path and a phase mismatch of an LO signal path of the second TX path, and the second phase difference is between a phase mismatch of an LO signal path of the first RX path and a phase mismatch of an LO signal path of the second RX path.

18. The mmWave AM of claim 15 , wherein the T2R relative phase comprises a sum of a first phase difference and a second phase difference, the first phase difference is between an initial phase of an LO signal path of the first TX path and an initial phase of an LO signal path of the second TX path, and the second phase difference is between an initial phase of an LO signal path of the first RX path and an initial phase of an LO signal path of the second RX path.