Analog Signal Switch Circuit With Nonlinear Capacitance Compensation
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Solution Overview
Problem
Existing electrical circuits used in mobile telecommunications for transmitting analogue signals suffer from signal distortion due to the non-linear capacitance characteristic of switches in the switched-off state, which affects transmission quality.
Innovation Solution
Incorporating a compensation circuit with non-linear capacitance, such as varactors or transistors, connected to the control connection of the switches to counteract the distortion caused by the switches in both the ON and OFF states, specifically using series-connected varactors or transistors to create an opposite curvature that compensates for the distortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If switches (field-effect transistors or PIN diodes) are used to connect or separate signal transmission paths, then transmission loss is reduced and switching speed is improved, but signal distortion occurs in the switched-off state due to non-linear capacitance
Solution Approach 1:
The patent converts the harmful non-linear capacitance effect into a beneficial compensation mechanism by introducing a compensation circuit with opposite non-linear capacitance characteristic. The compensation circuit's non-linear capacitance (with curvature to the right) counteracts the distortion produced by the switch's non-linear capacitance (with curvature to the left), transforming the harmful distortion effect into a useful signal restoration function.
Solution Approach 2:
The compensation circuit acts as an intermediary element between the switch and the signal transmission path. It mediates the interaction by introducing a compensating non-linear capacitance that counterbalances the switch's non-linear capacitance effect, thereby reducing signal distortion without interfering with the switch's primary function of connecting or separating signal paths.
2Reliability
If switches are brought into high-resistance state for signal separation, then path isolation is improved, but non-linear capacitance distortion is generated that affects transmission quality
Solution Approach 1:
The patent transforms the harmful capacitance distortion that occurs during signal separation into a beneficial effect by using a compensation circuit with opposite non-linear characteristic. The compensation circuit's non-linear capacitance counteracts the switch's non-linear capacitance, converting the information loss caused by distortion into preserved signal integrity.
3Reliability
If non-linear capacitance compensation is applied to reduce signal distortion, then transmission quality is improved, but device complexity increases due to additional compensation circuits
Solution Approach 1:
The patent changes the capacitance parameter characteristic by introducing elements with opposite non-linear capacitance behavior. By selecting compensation elements (such as varactors or transistors configured to exhibit non-linear capacitance with curvature to the right) that are parameter-matched to counterbalance the switch's non-linear capacitance (curvature to the left), the system achieves distortion compensation through parameter optimization rather than complex circuit topologies.
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
The compensation circuit significantly reduces signal distortion in the switched-off state, thereby enhancing the transmission quality of analogue signals across various frequency bands.
Implementation Method 1
In the switched-off state (OFF), known field-effect transistors have a capacitance characteristic as shown for example in FIG. 2... Owing to the non-linear characteristic, in the switched-off state (OFF) the field-effect transistor produces a distortion... the compensation circuit... comprises at least one non-linear capacitance
Data Source
AI summary
The invention relates to an electrical circuit (1) for transmitting a useful analogue signal, which has a signal transmission path (16) with an input path (2) and an output path (3) and at least one switch (6), with which the useful signal which is carried on the input path (2) can be connected through to the output path (3) or the signal transmission path (16) can be interrupted. According to the invention, a compensation circuit (4) which substantially compensates for a distortion of the useful analogue useful signal generated by the at least one switch (6) when it is switched off (OFF) is provided, wherein the compensation circuit (4) is connected to a control terminal (G) of the at least one switch (6) and comprises at least one non-linear capacitance.