A Method of Using Digital Switching to Realize Precise Phase Shift

Abstract

The invention discloses a method for realizing precise phase shift by means of a digital switch. The phase-shifting method is to shift the phase of the phase-locked loop reference frequency signal that generates the local oscillator signal. Firstly, a digital circuit is used to generate a signal with the same value as the reference frequency of the phase-locked loop, and the signal is divided into M angle regions. Then according to the output phase requirements, the signal is continuously switched between the selected angles using a random sequence, and the phase shift is completed through this phase modulation method. Then perform narrowband filtering on the modulated signal to obtain a pure reference frequency signal. Compared with the existing direction-shifting technology, the present invention can use digital circuits to realize accurate positioning without relying on digital / analog conversion and analog / digital conversion devices. Phase shifting has great advantages in terms of power consumption, price and integration. All phase shift elements can be easily integrated on a single ASIC chip, which can realize phase shift control of hundreds of channels while ensuring high phase resolution.

Description

technical field [0001] The invention relates to the field of satellite communications, in particular to a method for realizing precise phase shifting by means of digital switching. Background technique [0002] Array antennas have important applications in satellite communications. Among various array antennas, phased arrays have received extensive attention due to their excellent electrical scanning characteristics. Since the array beam pointing is controlled by the phase difference, the phase shifter is regarded as an extremely critical part of the phased array. [0003] Traditional phase shifters use analog phase shifting methods, such as switching phase shifters and vector modulation phase shifters, but because they use analog phase shifting, phase shifters have poor phase resolution, in the 360° period range. Usually there are only 4 to 6 phase-shifting steps, which is not enough for geostationary satellite systems that need to track satellites in real time. Digital ...

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Problems solved by technology

However, the high cost of digital beamforming also limits its application. The array requires a D / A converter and an A / D converter for each unit channel to receive and transmit respectively. For small systems with few channels said, this is acceptable, but too expensive and impractical for satellite communication systems that typically have hundreds of channels

Due to the development of direct digital synthesis (DDS), some other high-resolution digital phase-shifting techniques have also been developed, but similar to DBF, its application in phased arrays with a large number of channels is also limited due to the limited number of DDS channels. restricted

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