FDD Transceiver Calibration via Dynamic LO Frequency Switching

The patent applies dynamics by making the local oscillator frequency dynamic and reconfigurable. During normal operation, the LO operates at the receive frequency for down-conversion. During calibration mode, the LO frequency is dynamically changed to match the transmit frequency, enabling the receiver to process looped-back transmit signals. This frequency switching capability resolves the contradiction by allowing the system to adapt between FDD operation and calibration modes.

The patent introduces an intermediary calibration mode that bridges the gap between transmit and receive paths. By using a switch to route the transmit signal to the receiver input and reconfiguring the LO frequency, the system creates an intermediate calibration path that allows calibration without requiring separate hardware loops for each frequency. This intermediary mechanism enables calibration while maintaining FDD operation.

The patent applies universality by making the receiver and local oscillator serve multiple functions. The receiver can process both normal receive signals and looped-back transmit calibration signals. The local oscillator can operate at both receive frequency and transmit frequency. This multi-functionality allows I/Q mismatch calibration using existing hardware components, reducing the need for additional dedicated calibration hardware and minimizing system complexity.

The patent implements self-service by enabling the transceiver to perform its own calibration using its existing components. The receiver unit calibrates itself by processing looped-back transmit signals, and the local oscillator reconfigures itself to the appropriate frequency for calibration mode. This self-calibration capability eliminates the need for external calibration equipment or complex additional calibration circuits.