Semiconductor Switching Circuit With Pre-Discharge Control Path
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Solution Overview
Problem
High-frequency semiconductor switching devices face challenges in reducing switching time while maintaining signal integrity, as existing solutions increase chip area and power consumption due to the need for large output capacitance and current extraction capacity in negative voltage generating circuits.
Innovation Solution
The semiconductor switching device incorporates a control circuit with diodes and transistors connected between the output nodes and ground, along with inverters to drive the level shift circuit, allowing the control signal to switch from a blocking to conducting state before the potential changes, reducing switching time without increasing output capacitance or current extraction capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a negative voltage generating circuit is included to provide negative potential control signals, then the switching device can operate with proper control levels, but the switching time cannot be reduced due to the circuit's inherent limitations
Solution Approach 1:
The transistor is configured to switch from blocking state to conducting state before the output node potential switches from high level to low level. This preliminary action prepares the discharge path in advance, enabling faster voltage transition and reducing switching time while maintaining reliable control signal levels.
Solution Approach 2:
A diode is introduced as an intermediary component between the output node and the transistor. The diode enables controlled discharge of the output node capacitance through the transistor, facilitating faster voltage transitions without compromising the stability of the control signal levels generated by the negative voltage generating circuit.
2Reliability
If large output capacitance is used in the negative voltage generating circuit, then signal integrity is maintained, but chip area increases
Solution Approach 1:
The discharge path is prepared in advance by configuring the transistor to switch before the potential change occurs. This allows the output node capacitance to be discharged more efficiently through the controlled action of the transistor and diode, reducing the required capacitance value and thereby reducing chip area while maintaining signal integrity during switching transitions.
3Productivity
If large current extraction capacity is provided in the negative voltage generating circuit, then switching performance improves, but power consumption increases
Solution Approach 1:
The transistor is switched on before the potential change to prepare the discharge path. This preliminary action allows the capacitance to be discharged through a controlled current path, reducing the peak current extraction capacity required from the negative voltage generating circuit while achieving fast switching performance, thereby reducing power consumption.
Solution Approach 2:
The diode acts as an intermediary that enables controlled current flow during the discharge phase. This controlled discharge mechanism reduces the current extraction burden on the negative voltage generating circuit, improving switching speed without proportionally increasing power consumption.
Data Source
AI summary
A semiconductor switching device includes, on one semiconductor substrate: a switching circuit configured to switch connection states between a plurality of terminals; a negative voltage generating circuit; and a control circuit connected to the switching circuit and the negative voltage generating circuit and configured to supply a control signal to the switching circuit, the control circuit including: a level shift circuit with a low-potential power supply terminal connected to the negative voltage generating circuit and an output node connected to the switching circuit, the level shift circuit being configured to supply a negative potential signal as a control signal at a low level to the switching circuit; a diode with its anode connected to the output node of the level shift circuit; and a transistor with its drain-source path connected between the cathode of the diode and ground, the drain-source path switching from a blocking state to a conducting state before the potential of the output node of the level shift circuit switches from a high level to the low level.