Low-Cost Digital Phase-Shifting Technique Using Delta-Sigma Modulation for Satellite Communication Antenna Systems

Abstract

A low-cost digital phase-shifting technique using delta-sigma modulation is proposed in this article for satellite communication. The design methodology and working mechanism of the proposed phase-shifting scheme are presented. By employing delta-sigma modulation to tune the local oscillator (LO) phase-locked loop (PLL) reference’s phase, very precise phase resolution (theoretical 26 bits over 360°) can be achieved without digital-to-analog converter (DAC). The proposed scheme is simulated and verified using Simulink and shows good phase-shifting characteristics. As a proof-of-concept example, an eight-element active phased array receiver system prototype was designed, fabricated, and measured to confirm the feasibility of the proposed technique. The measured sidelobe level was approximately −12 dB and the gain flatness of less than 3 dB was obtained within the ±50° beam scanning range. Merits of low power consumption, low cost, and ease of integration can be achieved due to the removal of DACs, thus making this proposed technique possible to be implemented in programmable logic devices or application-specific integrated circuits (ASICs) and promising for future wireless communication systems, especially for the satellite communications.