Ultra-Wideband Signal Generator With Single-LO Low Phase Noise
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Solution Overview
Problem
Existing signal generators using multiple oscillators suffer from phase noise, limited flexibility, and signal degradation due to mixer imbalances and digital-to-analog converter imperfections, leading to frequency domain artifacts and IQ constellation errors.
Innovation Solution
An ultra-wideband signal generator utilizing a single local oscillator to generate carrier frequencies for I and Q signals, combined with dual DACs for error correction and a fixed LO system for low phase noise, enabling fast switching between bands with improved signal quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple oscillators are used to provide different carrier frequencies, then flexibility to generate various frequencies is improved, but phase noise increases
Solution Approach 1:
The patent combines multiple frequency generation functions into a single tunable oscillator, eliminating the need for multiple separate oscillators. This single oscillator generates all required carrier frequencies through tuning, thereby maintaining frequency flexibility while eliminating the phase noise that would be generated by multiple oscillators working together.
Solution Approach 2:
The tunable oscillator is designed to perform multiple frequency generation functions across different bands (e.g., L-band, S-band, C-band, X-band, Ku-band, K-band, Ka-band) within a single device. This universal oscillator replaces what would traditionally require multiple specialized oscillators, achieving both flexibility and low phase noise.
2Object-generated harmful factors
If fixed oscillators are used, then phase noise is reduced, but flexibility to generate different frequencies is limited
Solution Approach 1:
The patent employs a dynamic tunable oscillator that can adjust its operating frequency across multiple bands while maintaining the low phase noise characteristics of fixed oscillators. The oscillator's frequency is controlled through tuning mechanisms that allow it to adapt to different carrier frequency requirements without sacrificing phase noise performance.
3Adaptability or versatility
If mixer and DAC components are used, then signal generation capability is improved, but frequency domain artifacts and IQ constellation errors are introduced
Solution Approach 1:
The patent extracts and eliminates the problematic mixer and DAC components from the signal generation path by using a direct digital synthesis approach where the tunable oscillator directly generates the desired carrier frequencies. This removal of intermediate components eliminates the sources of frequency domain artifacts and IQ constellation errors that would otherwise be introduced by mixers and DACs.
Data Source
AI summary
A waveform generator includes a carrier band generator to produce a carrier signal, one or more selectable frequency multipliers to receive the carrier signal and to output a selected carrier signal having a frequency of a multiple of the carrier signal, at least two main digital-to-analog converters (DACs), each main DAC to receive a digital in-phase (I) or quadrature (Q) signals, and to convert the digital I and Q signals to analog I and Q signals in accordance with a control signal, at least two offset DACs, each offset DAC to receive the digital I or Q signals to convert the digital I and Q signals to analog I and Q signals in accordance with the control signal, a mixer to mix the analog I and Q signals with the selected carrier signal to produce an output signal, and a variable filter configured to produce a filtered output signal.