RF Switching Circuit Using Opposed Diodes for Fast Isolation
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Solution Overview
Problem
Existing RF switching circuits face challenges with large RF suppressing elements that cause energy storage, reduce switching speed, and require significant spatial volume, especially at high voltages, leading to unwanted interference and additional losses.
Innovation Solution
A switching circuit design utilizing a pair of diodes with opposite polarities in parallel signal paths, allowing for rapid switching by dissipating stored charge and reducing the need for large RF suppressing components, with optional RF suppressing elements to control current flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If RF suppressing elements are used to isolate DC control signal from RF signal, then isolation between DC and RF is improved, but the size of the elements becomes large and switching speed is reduced
Solution Approach 1:
The patent extracts the RF suppression function from traditional large inductors and capacitors and implements it using small diodes in parallel signal paths. The diodes are placed in series with DC control signal paths to provide RF suppression while maintaining compact size and fast switching speed, thereby separating the suppression function from bulky energy storage elements.
Solution Approach 2:
The patent changes the component parameters by using diodes with specific forward voltage drops and reverse recovery characteristics instead of traditional inductors and capacitors. This parameter change allows RF suppression with minimal energy storage, enabling faster switching while maintaining isolation between DC control signals and RF signals.
2Reliability
If RF suppressing elements are used to isolate DC control signal from RF signal, then isolation between DC and RF is improved, but spatial requirements increase
Solution Approach 1:
The patent extracts the RF suppression function from traditional large inductors and capacitors and implements it using small diodes in parallel signal paths. The diodes are placed in series with DC control signal paths to provide RF suppression while maintaining compact size and fast switching speed, thereby separating the suppression function from bulky energy storage elements.
Solution Approach 2:
The patent uses multiple small diodes in parallel signal paths to replicate the RF suppression function that would traditionally require a single large inductor or capacitor. This copying approach distributes the suppression function across multiple compact components, reducing overall spatial requirements while maintaining isolation effectiveness.
3Reliability
If RF suppressing elements are used to isolate DC control signal from RF signal, then isolation between DC and RF is improved, but additional losses occur
Solution Approach 1:
The patent changes the component parameters by using diodes with specific forward voltage drops and reverse recovery characteristics instead of traditional inductors and capacitors. This parameter change allows RF suppression with minimal energy storage, enabling faster switching while maintaining isolation between DC control signals and RF signals.
Solution Approach 2:
The patent converts the typically harmful reverse recovery charge in diodes into a beneficial feature by using the parallel signal path configuration. The second diode in the parallel path quickly removes stored charge during switching transitions, and this charge removal mechanism actually improves switching speed while the small size of the diodes minimizes resistive losses compared to traditional RF suppressing elements.
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 solution achieves switching times under a microsecond and minimizes impedance detuning, reducing spatial requirements and manufacturing costs while maintaining circuit integrity at high voltages.
Implementation Method 1
The control circuit comprises a first signal path, wherein the first signal path comprises at least one first diode being configured to provide the control signal to the switchable element. The control circuit also comprises a second signal path, wherein the second signal path is arranged in parallel to the first signal path. The second signal path comprises at least one second diode, wherein the at least one second diode is arranged with opposite polarity compared to the at least one first diode.
Data Source
AI summary
A switching circuit for selectively closing or interrupting a radio frequency (RF) signal path includes a switchable element that is switchable between an on-state and an off-state. The switching circuit also includes a control circuit and a power supply circuit. The control circuit is configured to apply a control signal provided by the power supply circuit to the switchable element. The control signal includes a control voltage and/or a control current. The control circuit includes a first signal path that includes at least one first diode being configured to provide the control signal to the switchable element. The control circuit comprises a second signal path. The second signal path is arranged in parallel to the first signal path. The second signal path includes at least one second diode that is arranged with opposite polarity compared to the at least one first diode.