Translational Phase Lock Loop and Synthesizer That Eliminates Dividers

Abstract

This invention describes a method by which a low cost low phase noise Phase Locked Loop or Phase Locked Loop based Frequency Synthesizer can be realized. The new method, called a Translational Phase Lock Loop or TPLL, allows the conversion of a traditional voltage controlled oscillator or VCO signal so that the phase noise of the VCO signal is substantially identical to the noise that the loop is aimed to correct via comparison to a low noise reference oscillator. It overcomes additional problems associated with traditional and prior art phase lock loops in terms of unwanted spurious signals, complexity, and cost.

Description

CROSS RELATION TO RELATED APPLICATIONS[0001]Not ApplicableFIELD OF THE INVENTION[0002]This invention pertains to a method to create high purity broadband signals from a low noise tunable source using novel signal processing and synthesis techniques.DEFINITION OF TERMS[0003]Voltage Controlled Oscillator (VCO): An oscillator whose frequency is controlled by the application of a voltage (or current) to a tuning port.[0004]Phase Lock Loop (PLL): A closed loop system where the output of a VCO is locked to a Reference Oscillator within a certain bandwidth.[0005]TCXO: Temperature Controlled Crystal Oscillator. The Crystal Oscillator output is kept stable by a temperature sensor that is used to electronically control the frequency.[0006]OCXO: Oven Controlled Crystal Oscillator. A heater element is used to control the temperature of the oscillator circuit. Usually provides better stability than a TCXO, but is more expensive.[0007]DDS: A Direct Digital Synthesizer. Is used to create arbitrary...

AI Technical Summary

Benefits of technology

[0017]Our invention is aimed at solving the two biggest issues associated with prior art by doing exactly this. It is non-intuitive, but it is simple and effective.

[0018]Prior art attempts to solve this same issue have involved using multiple frequency multipliers and dividers in order to provide the same effect. They involve the necessity to build two loops to achieve the goal, a first loop that is a traditional loop that sets the VCO at the frequency where it needs to be, and then a second loop that provides a frequency translation Fmixer that can only then be brought into the picture. Our approach needs only one loop, is faster to lock, is more accurate, and costs less.

[0019]This is demonstrated in the detailed description of the invention that follows. Our invention provides almost all the advantages of the DDS and the PLL, while eliminating all their disadvantages. It allows the cleanup of the noisiest aspects of the most typical noisy VCOs.

Problems solved by technology

The fact that a PLL assures that the loop adheres to the phase noise of the RO is in itself not sufficient to assure a compliant phase noise spectrum at the output.

As can be appreciated by anyone familiar with the art, this is not easy.

To provide a signal to the phase detector at the same frequency as the RO, but with the same phase noise characteristics as the VCO over possibly multi-octave or decade bandwidths has been heretofore considered extremely expensive if not impossible.

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