Direct digital synthesis-based (DDS-based) device and method for synthesizing broadband microwave local-oscillation multi-ring frequency

Abstract

The invention discloses a direct digital synthesis-based (DDS-based) device and a method for synthesizing broadband microwave local-oscillation multi-ring frequency. A high-performance direct digital frequency synthesis chip is used for substituting a decimal ring in the universal multi-ring frequency synthesis, so that the loop design of the local oscillation narrowband frequency scanning can be simplified; and meanwhile, the DDS-based single-ring lock phase frequency synthesis technology is adopted during the local oscillation broadband scanning. Against for the complexity of the multi-ring lock-phase frequency synthesis of the broadband microwave local oscillation and the open-loop property of the broadband scanning, the DDS is used for substituting the decimal frequency division, so that the design is simplified, the difficulty in realization is small, convenience in debugging is realized, and the cost is reduced; and a voltage control oscillator (VCO) loop also stays at a locking state in broadband quick scanning, so that the output frequency precision of a broadband local oscillation signal is greatly improved.

Description

technical field [0001] The invention relates to a microwave local oscillator multi-ring frequency synthesis method, in particular to a microwave local oscillator multi-ring frequency synthesis method realized by using DDS. Background technique [0002] The broadband microwave local oscillator is the key technology in the design of current receivers and transmitters. The broadband microwave local oscillator has an important impact on many important technical indicators of the whole machine, such as frequency accuracy, frequency resolution, frequency coverage, spurious response and single sideband noise etc. [0003] The development of broadband microwave local oscillator synthesis technology has experienced open, multi-loop frequency-locked and multi-loop phase-locked. Improve frequency stability and local oscillator phase noise indicators. Multi-loop frequency synthesis The local oscillator is composed of four main loops, namely the reference loop, fractional loop, sampli...

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Problems solved by technology

It should be pointed out here that the frequency synthesis of this multi-ring phase-locked structure is only in a small frequency scanning range (generally, the span is less than 10MHz, hereinafter referred to as "narrowband scanning", and when the span is greater than 10MHz, hereinafter referred to as "broadband scanning") ”); in the case of large span, in order to ensure the scanning speed, the VCO loop generally works in an open-loop state, and the frequency output accuracy is relatively poor

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