CMOS Non-Reciprocal Circulator Using N-Path Filter and Ring Section
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Solution Overview
Problem
The implementation of full-duplex wireless communications is hindered by the need for non-reciprocal circulators, which are typically bulky and expensive due to their reliance on ferrite materials that cannot be integrated into CMOS IC technology and require external magnets.
Innovation Solution
The development of non-reciprocal circulators comprising a 3λ/4-long ring section and an N-path filter, where the 3λ/4-long ring section is formed from lumped capacitor-inductor-capacitor networks or transmission lines, and the N-path filter has multiple paths connected to ports, enabling unidirectional signal flow without the need for external magnets, suitable for integration into CMOS ICs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ferrite materials are used to implement non-reciprocal circulators, then non-reciprocal signal transmission is achieved, but the device becomes bulky and expensive with external magnet requirements
Solution Approach 1:
The patent replaces the mechanical/ferrite-based non-reciprocal system with an electrical system using varactor diodes and switching networks. The mechanical external magnet is substituted by electrical control signals that modulate the varactor diodes, achieving non-reciprocity through electrical means rather than magnetic materials.
Solution Approach 2:
The patent changes the operating parameters by using time-varying capacitance values in the varactor diodes controlled by switching networks. The capacitance values are dynamically adjusted through electrical control signals, creating non-reciprocal behavior without requiring ferrite materials or external magnets.
2Reliability
If ferrite materials are used in circulators, then non-reciprocity is achieved, but integration into CMOS IC technology becomes impossible
Solution Approach 1:
The patent substitutes the incompatible ferrite material system with CMOS-compatible electronic components including varactor diodes, switching networks, and transmission lines. This electrical implementation can be manufactured using standard CMOS IC fabrication processes, enabling integration that was impossible with ferrite materials.
Solution Approach 2:
The patent creates a composite structure using multiple CMOS-compatible materials and components: varactor diodes for capacitance modulation, transmission lines for signal routing, and switching networks for control. This composite electronic system achieves non-reciprocity while being fully compatible with CMOS manufacturing.
3Reliability
If external magnets are used in ferrite-based circulators, then non-reciprocal signal flow is achieved, but the device becomes bulky and expensive
Solution Approach 1:
The patent replaces the heavy external magnet with lightweight electronic control circuits. The magnetic field generation function is substituted by electrical control signals that modulate the varactor diodes, eliminating the need for bulky magnetic components while maintaining non-reciprocal signal flow.
Solution Approach 2:
The patent creates an electrical equivalent of the magnetic field effect by using controlled capacitance variations in varactor diodes. The electrical control signals replicate the function of the external magnet's magnetic field, achieving the same non-reciprocal effect without the physical mass of magnetic materials.
Data Source
AI summary
In accordance with some embodiments, non-reciprocal circulators are provided, the circulators comprising: a 3λX/4-long ring section having a first end and a second end, wherein λ is an operating wavelength of the non-reciprocal circulator; and a N-path filter having a first port, a second port, and N-paths, each of the N-paths being connected to the first port and the second port. In some of these embodiments, the 3λ/4-long ring section includes a transmit port, an antenna port, and a receive port. In some of these embodiments, the transmit port is λ/4 away from the antenna port. In some of these embodiments, the antenna port is λ/4 away from the receive port. In some of these embodiments, the receive port is at the first port of the N-path filter.