Calibration circuit for calibrating phases and gains between channels in multi-channel beamforming system, multi-channel beamforming system including the same and channel calibration method using the same

A multi-channel beamforming system comprising:

• a plurality of channels;
• and
• a calibration circuit connected to the plurality of channels, the calibration circuit configured to calibrate phases and gains between the plurality of channels,
• wherein the calibration circuit includes:
• a selection unit connected to the plurality of channels, the selection unit configured to select two channels from among the plurality of channels, to provide a test signal to the selected two channels, and to receive a test result signal from the selected two channels;
• a power detector configured to detect power of the selected two channels based on the test result signal;
• an analog-to-digital converter configured to perform an analog-to-digital conversion on an output of the power detector;
• and
• a calibrator configured to calibrate the phases and the gains between the plurality of channels based on an output of the analog-to-digital converter,
• wherein one of the plurality of channels is set as a reference channel, phases and gains of remaining channels other than the reference channel among the plurality of channels are sequentially optimized based on the reference channel, and a phase and a gain of the reference channel is optimized based on one of the remaining channels.

A channel calibration method for calibrating phases and gains between a plurality of channels included in a multi-channel beamforming system, the plurality of channels including a first channel to an N-th channel, where N is a natural number greater than or equal to three, the channel calibration method comprising:

• selecting the first channel as a reference channel;
• sequentially selecting a second channel to the N-th channel as a comparison channel;
• sequentially setting the second channel to the N-th channel to have lowest power at a first phase;
• selecting the second channel as the reference channel;
• selecting a third channel as the comparison channel;
• setting the third channel to have lowest power at a second phase different from the first phase;
• selecting the third channel as the reference channel;
• selecting the first channel as the comparison channel;
• and
• setting the first channel to have lowest power at the first phase.

A channel calibration method for calibrating phases and gains between a plurality of channels included in a multi-channel beamforming system, the plurality of channels including a first channel to an N-th channel, where N is a natural number greater than or equal to three, the channel calibration method comprising:

• selecting the first channel as a reference channel;
• sequentially selecting an (N/2+1)-th channel to the N-th channel as a comparison channel;
• sequentially setting the (N/2+1)-th channel to the N-th channel to have lowest power at a first phase;
• selecting the (N/2+1)-th channel as the reference channel;
• sequentially selecting the first channel to an N/2-th channel as the comparison channel;
• and
• sequentially setting the first channel to the N/2-th channel to have lowest power at the first phase or at a second phase different from the first phase.