IQ Mixer Layout Using a Shared Degeneration Inductor
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Solution Overview
Problem
Conventional IQ mixers have large circuit dimensions due to separate degeneration inductors, which hinders the integration of RF transceiver functionality onto a single die and increases manufacturing costs.
Innovation Solution
A compact IQ mixer design utilizing a shared degeneration inductor among pairs of Gilbert cells, each comprising current generators and switching networks, to convert RF signals into mixed signals without affecting circuit performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate degeneration inductors are used in each Gilbert cell, then circuit performance is maintained, but circuit dimensions become large
Solution Approach 1:
The patent combines multiple separate degeneration inductors into a single shared degeneration inductor that is coupled to multiple Gilbert cells. This merging approach reduces the total circuit area while maintaining the necessary performance characteristics through careful design of the shared inductor coupling.
Solution Approach 2:
The shared degeneration inductor serves multiple Gilbert cells simultaneously, making it a multi-functional component. This universal component performs the degeneration function for all connected Gilbert cells, eliminating the need for separate inductors and reducing overall circuit complexity and area.
2Reliability
If separate degeneration inductors are used in each Gilbert cell, then individual cell performance is optimized, but manufacturing costs increase
Solution Approach 1:
By merging separate inductors into a shared component, the patent reduces the total number of discrete elements that need to be manufactured and assembled, thereby lowering manufacturing costs while maintaining individual cell performance through proper coupling design.
Solution Approach 2:
The shared degeneration inductor provides a universal solution that benefits multiple Gilbert cells, reducing per-cell manufacturing cost through component sharing while maintaining the performance optimization that separate inductors would provide for each cell.
3Area of stationary object
If circuit dimension is reduced for integration, then die size decreases, but circuit mismatch increases
Solution Approach 1:
The shared degeneration inductor provides a common reference impedance for multiple Gilbert cells, which helps maintain matching conditions even when the overall circuit is scaled down for smaller die size. The common inductor acts as a stabilizing element that reduces mismatch variations.
Data Source
AI summary
An IQ mixer and a method thereof. The IQ mixer comprises a pair of Gilbert cells and a degeneration inductor. Each pair of Gilbert cells comprises a pair of first current generators and a pair of switching networks. The pair of first current generators converts an RF signal pair to currents respectively. The pair of switching networks, coupled to the first current generator, modulates the converted RF signal pair with an oscillation signal pair to generate a mixed signal pair. The degeneration inductor is coupled to all pairs of the first current generators, such that it is shared by the pair of Gilbert cells.