Switch Circuit Impedance Correction for High-Frequency Signal Distortion
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Solution Overview
Problem
Existing switch circuits for high-frequency signals suffer from significant even-order distortion due to asymmetric impedance changes when FETs are in the OFF state, which is not adequately addressed by existing configurations that either increase layout area, fail to eliminate distortion across multiple frequencies, or result in increased power consumption.
Innovation Solution
The introduction of correction circuits with capacitance elements connected between high-frequency terminals and gate electrodes of FETs to balance impedance, ensuring it changes symmetrically with the direct-current potential, thereby reducing even-order distortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If FETs are used in switch circuit for high-frequency signals, then switching function is achieved, but even-order distortion occurs due to asymmetric impedance changes
Solution Approach 1:
The patent applies asymmetry principle by introducing capacitance elements with specific values to deliberately create asymmetric impedance compensation. The first capacitance element connected to the first FET and the second capacitance element connected to the second FET have different values to counterbalance the asymmetric impedance changes caused by the FETs' OFF state, thereby reducing even-order distortion while maintaining switching functionality.
Solution Approach 2:
The patent uses capacitance elements as intermediary components between the FET gate electrodes and the signal path. These capacitance elements mediate the impedance changes by providing a frequency-dependent impedance that compensates for the asymmetric behavior of FETs in the OFF state, thus reducing even-order distortion without affecting the switching function.
2Object-generated harmful factors
If capacitance elements are added to correct impedance asymmetry, then even-order distortion is reduced, but device complexity increases
Solution Approach 1:
The patent applies local quality principle by adding capacitance elements only at specific locations where impedance asymmetry occurs - namely at the gate electrodes of the FETs in the OFF state. Rather than redesigning the entire circuit, the capacitance elements are locally inserted to compensate for the asymmetric impedance changes, thus reducing even-order distortion with minimal increase in device complexity.
3Ease of operation
If gate width of FETs is increased, then switching capability is improved, but parasitic capacitance increases and switch characteristics deteriorate
Solution Approach 1:
The patent applies parameter changes principle by modifying the impedance characteristics of the switch circuit through the introduction of capacitance elements. By carefully selecting the values of these capacitance elements, the overall impedance behavior is adjusted to compensate for the increased parasitic capacitance from larger FET gate widths, thereby maintaining good switch characteristics while preserving enhanced switching capability.
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 configuration effectively reduces even-order distortion in switch units during the OFF state, improving signal transmission quality while maintaining low power consumption and compact layout.
Implementation Method 1
a first capacitance element 51, 54 connected between first high-frequency terminal 1 and gate electrode of FET 31, 34; a second capacitance element 52, 55 connected between first high-frequency terminal 1 and gate electrode of FET 32, 35; a third capacitance element 53, 56 connected between first high-frequency terminal 1 and gate electrode of FET 33, 36
Data Source
AI summary
A switch circuit for passing or blocking a high-frequency signal includes a correction circuit for correcting an impedance component that exists in the switch circuit and that changes asymmetrically with the direct-current potential as a reference such that impedance as seen from either high-frequency terminal changes symmetrically with the direct-current potential as a reference in response to positive and negative changes that take the direct-current potential of the high-frequency signal as a reference.