Ring Mixer Resistor Network for Better Linearity and Isolation
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Solution Overview
Problem
Mixers, such as diode ring and FET ring mixers, face challenges in improving linearity due to inherent non-linear characteristics of their elements, which affect cross modulation, harmonic generation, gain compression, and signal-to-noise and distortion ratio (SNDR).
Innovation Solution
Incorporating parallel shunt resistors in the ring mixer to reduce non-linear resistance and capacitance effects, and further enhancing linearity by adding series resistors, which improves isolation, symmetry, and reduces even order harmonics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If shunt resistors are added in parallel with diodes, then linearity is improved and non-linear effects are reduced, but device complexity increases
Solution Approach 1:
The mixer circuit is segmented by adding separate shunt resistor components in parallel with each diode, allowing the non-linear characteristics of diodes to be compensated independently. This segmentation enables precise control of linearity without requiring complete circuit redesign.
Solution Approach 2:
Shunt resistors are introduced as intermediary elements between the diodes and ground, acting as mediators that provide alternative current paths to reduce the impact of non-linear resistance and capacitance effects in the diodes, thereby improving overall linearity.
2Reliability
If series resistors are added to the ring mixer, then isolation and symmetry are improved, but device complexity increases
Solution Approach 1:
Series resistors are strategically placed at specific locations in the ring mixer where isolation and symmetry are most needed. This local quality approach allows targeted improvement of circuit performance without uniformly increasing complexity throughout the entire circuit.
Solution Approach 2:
The series resistors are configured to create controlled asymmetry in the circuit that actually enhances symmetry in signal paths. By introducing deliberate resistive elements, the circuit achieves better balance and isolation between different signal paths.
3Manufacturing precision
If shunt and series resistors are added to reduce non-linear effects, then conversion loss is reduced and input 1 dB compression point increases, but the number of components increases
Solution Approach 1:
Multiple resistor functions are merged into a unified resistor network configuration where shunt and series resistors work together as an integrated system. This combining approach reduces the total number of discrete components needed compared to separate compensation circuits.
Solution Approach 2:
The added resistors serve multiple functions simultaneously: they provide linearity improvement, enhance isolation, improve symmetry, and reduce non-linear effects. This multi-functionality reduces the need for additional separate components that would otherwise be required to achieve each benefit individually.
Data Source
AI summary
Mixers with improved linearity are disclosed. A diode or FET ring mixer is implemented with at least one parallel shunt element coupled with the ring mixer, the shunt element providing shunt to a diode or FET, for example, to reduce the effect of nonlinear or off resistance and/or capacitance. Linearity, isolation, symmetry, even order harmonics of the ring mixer, or any combination thereof can be improved as a result. The linearity of the ring mixer with parallel shunt resistors can be further improved by adding series resistors in the ring according to certain embodiments.