Coupled Oscillator Voltage Sharing for Low-Noise RF Signals
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Solution Overview
Problem
The reduction in supply voltages in silicon technologies limits the signal-to-noise ratio (SNR) in RF systems due to phase noise, affecting spectral purity, particularly in telecommunications applications, and existing solutions either increase manufacturing costs or degrade circuit efficiency.
Innovation Solution
An electronic system comprising two mutually coupled oscillators with a shared power supply and a feedback loop to maintain a constant dynamic ground potential, allowing constructive combination of oscillation signals to improve SNR.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If supply voltage is reduced to ensure reliable transistor operation, then transistor reliability is improved, but signal amplitude and signal-to-noise ratio deteriorate
Solution Approach 1:
The oscillator is divided into two differential pairs (first and second differential pairs) that share the supply voltage. Each differential pair operates at a lower voltage swing, ensuring reliable transistor operation, while their combined output achieves the required high signal amplitude. This segmentation allows the system to maintain both transistor reliability and adequate signal power simultaneously.
2Power
If new transistor families (GO2, LDMOS, high-voltage transistors) are used to maintain higher voltages, then signal amplitude is improved, but manufacturing cost increases
Solution Approach 1:
Instead of using expensive specialized high-voltage transistors, the invention segments the voltage swing across two standard transistors in differential pairs. This approach achieves the required signal amplitude using conventional transistor families, thereby avoiding increased manufacturing costs while maintaining adequate signal power.
3Reliability
If supply voltage is reduced, then transistor operation reliability is improved, but phase noise increases
Solution Approach 1:
The invention segments the signal generation function across two differential pairs operating in parallel. Each pair contributes to the overall signal and shares the phase noise burden. The combined output achieves lower total phase noise compared to a single differential pair operating at reduced voltage, while maintaining reliable transistor operation.
Solution Approach 2:
Two differential pairs are merged in parallel to combine their output signals. This merging provides signal addition while averaging out phase noise contributions, resulting in improved spectral purity compared to a single differential pair operating at lower voltage swing.
4Power
If voltage is shared between two differential pairs, then signal amplitude is improved, but circuit complexity increases
Solution Approach 1:
The oscillator is segmented into two differential pairs with systematically arranged components. The first differential pair uses PMOS transistors while the second uses NMOS transistors, with symmetric connection topologies. This systematic segmentation achieves high signal amplitude while keeping the increased complexity manageable through structural regularity and component reuse.
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
This approach enhances the SNR by stabilizing the dynamic ground voltage through a feedback loop, resulting in improved spectral purity and reduced phase noise, achieving higher signal amplitudes with better circuit efficiency.
Implementation Method 1
a feedback loop suitable for maintaining the potential of said dynamic ground point at a constant level
Implementation Method 2
each said oscillator comprising an electrical resonator
Data Source
Figure 1A~1C
Figure 2A~2C
Figure 3A~3D
AI summary
Electronic system comprising a first (OSC1) and a second (OSC2) oscillator mutually coupled and having the same resonance frequency, each said oscillator comprising an electric resonator (RES1, RES2), an active cell (CA1, CA2) having a resistance of small negative signal connected to said electrical resonator, a power supply terminal (AE1, AE2) of said active cell, an output (S1, S2) for an oscillation signal (s_osc1, s_osc2) and a connection terminal (CM1, CM2) to a ground point, characterized in that: - the electrical supply terminal (AE2) of the second oscillator and the connection terminal (CM1) to a ground point of the first oscillator are connected to the same point (MD ), called dynamic mass; and - the system also comprises a differential amplifier (CMFB) forming, with the active cell of one of said oscillators, a feedback loop adapted to maintain the potential of said dynamic ground point at a constant level, a function of said voltage reference.