Integrated Circuit Design to Minimize Parasitic Capacitance
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Summary
Problems
Larger crosspoint switch die sizes lead to increased parasitic capacitance, limiting dynamic performance due to long signal lines and numerous circuit elements, causing issues like ringing, poor settling times, and oscillatory behavior, and require external feedback capacitors.
Innovation solutions
Incorporating shield conductors adjacent to feedback signal lines within the integrated circuit to interrupt parasitic capacitance and generate capacitance between feedback lines and output terminals, potentially eliminating the need for external feedback capacitors.
TRIZ Analysis
Specific contradictions:
General conflict description:
Principle concept:
If crosspoint switch die size is increased to provide larger input and output counts, then the switch capacity and versatility are improved, but parasitic capacitance increases which degrades dynamic performance
Why choose this principle:
A ground isolation conductor is introduced as an intermediary element between the feedback signal line and the ground plane. This conductor acts as a mediator to block the formation of parasitic capacitance between the feedback line and ground, thereby eliminating the harmful capacitive coupling while allowing the larger die size to maintain its switching capacity.
Principle concept:
If signal line length is increased to accommodate more circuit elements, then the switch functionality is improved, but parasitic capacitance increases causing ringing and oscillation
Why choose this principle:
The ground isolation conductor serves as a mediator that interrupts the parasitic capacitance path between the feedback signal line and ground. By placing this isolation conductor adjacent to the feedback signal line, the harmful capacitive coupling is blocked, preventing ringing and oscillation while allowing the signal line to extend across the larger die to provide enhanced switch functionality.
Application Domain
Data Source
AI summary:
Incorporating shield conductors adjacent to feedback signal lines within the integrated circuit to interrupt parasitic capacitance and generate capacitance between feedback lines and output terminals, potentially eliminating the need for external feedback capacitors.
Abstract
An amplifier structure includes shield conductors that are provided spatially adjacent to elongated feedback signal lines that couple a feedback circuit to an amplifier input. The shield conductors are provided between the feedback signal lines and a ground plane, which interrupts a parasitic capacitance that otherwise would be established between the feedback signal line and ground. The shield conductors are electrically coupled to the amplifier's outputs which create a capacitance between the output terminal and the feedback signal line. In some embodiments, the capacitance generated between the output terminal and the feedback signal line can suffice as a capacitor in a feedback path of the amplifier and be contained in an integrated circuit die on which the amplifier is manufactured. Optionally, a structure may be provided that eliminates common mode signals on the feedback lines while simultaneously preserving the common mode signals on the amplifier output terminals. In this option, a second amplifier is provided that, in response to common mode variations at the output terminal, generates counterbalancing voltage variations on a second circuit that is coupled to the feedback lines at their source. The two variations cancel each other out at nodes from which the feedback lines originate, which substantially reduces feedback common mode variation even when there is common mode variation at the output terminals.