Harmonic VCO Signal Source for Wideband Low-Phase-Noise Tuning
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Solution Overview
Problem
Existing tunable signal sources face challenges in achieving low phase noise and a wide tuning range, particularly at high frequencies, as phase noise degrades with frequency increase and traditional methods result in limited tuning range.
Innovation Solution
A frequency tunable signal source comprising two Voltage Controlled Oscillators (VCOs) and a Fixed Frequency Oscillator (FFO), connected through a mixer with ON/OFF switches controlled by a unit, allowing for harmonic frequency combinations and an additional input to generate a wide range of frequencies with low phase noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If frequency multipliers are used to up-convert a low frequency VCO signal, then phase noise performance is improved, but phase noise degrades by 6 dB at every doubling of the oscillation frequency
Solution Approach 1:
The patent divides the frequency synthesis function into multiple segments: a low-frequency VCO, frequency multipliers, and a mixer with a fixed-frequency oscillator. This segmentation allows each component to operate in its optimal frequency range, with the VCO operating at low frequency where phase noise is naturally lower, and the frequency multiplication and mixing stages handling the frequency conversion while managing phase noise degradation through careful design.
2Measurement precision
If a mixer and fixed frequency oscillator are used to up-convert frequency, then phase noise degradation is alleviated, but tuning range becomes relatively small
Solution Approach 1:
The patent extends the tuning range by utilizing not only the fundamental frequency of the VCO but also its harmonic frequencies (2nd, 3rd, 4th harmonics). By switching between different harmonic frequencies of the VCO and combining them with the fixed-frequency oscillator in the mixer, the system achieves a much wider overall tuning range while maintaining good phase noise performance across the extended bandwidth.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution provides a tunable signal source with improved phase noise performance and a wide tuning range, capable of operating at high frequencies, such as 60 GHz and above, by seamlessly covering frequency ranges through harmonic combinations and frequency shifting.
Implementation Method 1
a mixer with a first and a second input port as well as an output port, and further comprises a control unit which controls ON/OFF switches, by means of which switches two of said signals are switchably connected to the first input port and the other two signals are switchably to the other input port
Data Source
AI summary
A frequency tunable signal source (100) with first (105) and a second (115, 315) oscillators, each of which outputs a signal at a fundamental frequency (f1, f2) and at least one signal at a harmonic frequency (f1′, f2′) and a mixer (120) with first (121) and second (122) input ports and an output port (124), and a control unit (110) which controls switches (S1, S2, S3, S4), by means of which two of said signals (f1, f2, f1′, f2′) are switchably connected to the first input port. The other two signals are switchably to the other input port, with one switch (S1, S2, S3, S4) for each signal (f1, f2, f1′, f2′). There is also comprised a third oscillator (125), with an output signal connected to a third input port (123) of the mixer (120). At least one of the oscillators (105, 115, 315, 125) is a VCO, a Voltage Controlled Oscillator.