Integrated RF Phase Shifter With High-Isolation Switching
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Solution Overview
Problem
Conventional RF phase shifter circuits face challenges in achieving high isolation without introducing insertion loss and in reducing die area, especially for applications requiring high-resolution phase shifting and isolation from external circuitry.
Innovation Solution
The integration of a high-isolation function within the phase shifter circuit using independent switch control signals and a switchable shunt termination resistor, allowing for a distinct high-isolation state without adding insertion loss, and combining this with bracketing attenuator circuits to reduce die size and increase isolation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional isolation switches are used in phase shifter circuits, then isolation from external circuitry is achieved, but insertion loss is introduced
Solution Approach 1:
The patent combines the isolation switch function with the phase shifter circuit by integrating the switchable shunt termination resistor directly into the phase shifter unit cell structure. This merging eliminates the need for separate external isolation switches, thereby achieving isolation without introducing additional insertion loss that would result from separate switch components.
Solution Approach 2:
The phase shifter circuit is designed to perform multiple functions: phase shifting and isolation. By making the isolation function integral to the phase shifter unit cell, the circuit achieves multi-functionality where the same structure provides both phase adjustment and isolation capabilities without requiring separate dedicated components for each function.
2Reliability
If isolation switches are added to improve isolation, then isolation performance increases, but die area increases
Solution Approach 1:
By merging the isolation function into the existing phase shifter unit cell structure, the patent avoids adding separate isolation switch components that would increase die area. The isolation capability is achieved using the same circuit elements already present in the phase shifter, thereby improving isolation performance without expanding the overall die area.
3Reliability
If high-isolation mode is implemented, then isolation from external circuitry is improved, but circuit complexity increases
Solution Approach 1:
The phase shifter unit cell is designed with multi-functionality, where the same circuit elements serve both phase shifting and isolation purposes. This universal design approach allows the circuit to achieve high-isolation mode without requiring separate dedicated isolation components, thereby improving isolation while maintaining relatively simple circuit architecture.
Data Source
AI summary
A phase shifter unit cell or a connected set of such cells that can be well isolated from external circuitry and which do not introduce insertion loss into an RF signal path, exhibit good return loss, and further provides additional advantages when combined with bracketing attenuator circuits. More particularly, embodiments integrate a high-isolation function within a phase shifter circuit by breaking the complimentary nature of the control signals to a phase shifter cell to provide greater control of switch states internal to the phase shifter cell and thus enable a distinct high-isolation state, and by including a switchable shunt termination resistor for use in the high-isolation state. Some embodiments are serially coupled to attenuator circuits to enable synergistic interaction that reduces overall die size and/or increases isolation. One such embodiment positions a high-isolation phase shifter cell in accordance with the present invention between bracketing programmable attenuators.