A 40-50 GHz RF Front-End with Integrated Local Oscillator Leakage Calibration

Area of Science:

• Electrical Engineering
• Wireless Communication Systems
• Integrated Circuit Design

Background:

• High-frequency transmitters require precise control over signal integrity to meet stringent communication standards.
• Image and local oscillator (LO) leakage signals are critical impairments in radio frequency (RF) front-ends that degrade performance.
• Existing solutions often require complex post-fabrication calibration, increasing cost and complexity.

Purpose of the Study:

• To develop a novel transmitter (TX) front-end operating in the 40-50 GHz band.
• To integrate amplitude and phase imbalance tuning for improved image signal rejection.
• To implement self-calibration mechanisms for LO leakage and image signal suppression.

Main Methods:

• Design of a differential quadrature mixer with integrated amplitude and phase imbalance tuning.
• Incorporation of a power amplifier (PA) for signal amplification.
• Integration of a detection mixer (DM) for LO leakage and image signal monitoring and calibration.
• Utilizing an in-phase quadrature (IQ) signal generator for LO signal generation and calibration.

Main Results:

• Achieved over 30 dBc image signal rejection across the 40-50 GHz band without post-calibration.
• Reduced LO leakage by more than 10 dB through an integrated calibration module.
• Maintained a 1 dB compressed output power (OP1 dB) above 13.5 dBm at 1 GHz intermediate frequency (IF).
• Demonstrated compliance with IEEE 802.11aj standards up to 64-quadrature amplitude modulation (QAM).

Conclusions:

• The proposed TX front-end effectively suppresses image and LO leakage signals through integrated calibration.
• The design achieves high performance metrics, including output power and error vector magnitude (EVM), meeting IEEE 802.11aj requirements.
• This integrated approach offers a robust solution for next-generation high-frequency wireless systems.