Negative Voltage Charge Pump Recovery for Switch Break-Before-Make
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Solution Overview
Problem
In systems with multiple switches, such as wireless communication systems, there is a challenge in ensuring that one switch is fully turned off before another is turned on to avoid feedback loops and system instability, particularly due to the significant capacitance of low threshold switches that require negative voltage biasing for isolation.
Innovation Solution
A switch activation system incorporating a fast recovery negative voltage charge pump and load monitoring, which includes a charge pump to drive a negative voltage node to a predetermined level, a load monitor to assert a break done signal when the voltage recovers, and a switch driver to turn on switches only after the break done signal is asserted, ensuring complete off-state before activation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If low threshold switches are used to achieve low on resistance, then on resistance is reduced, but significant capacitance causes delayed switch off time
Solution Approach 1:
The charge pump is activated in advance to generate the negative voltage required for turning off the switch. The load monitor continuously monitors the negative voltage node and asserts the break done signal in advance when the voltage reaches the predetermined level, so that when switching is needed, the system is already prepared and can execute the turn-off operation immediately without delay.
Solution Approach 2:
The load monitor provides real-time feedback on the voltage level at the negative voltage node. This feedback mechanism allows the system to detect when the negative voltage has been successfully established or recovered, and use this information to control the timing of switch activation, ensuring proper sequencing and avoiding conflicts.
2Reliability
If switches are turned off completely with negative voltage biasing, then off isolation is improved, but the capacitance requires longer charging/discharging time
Solution Approach 1:
The load monitor continuously monitors the negative voltage node voltage level and provides feedback to determine when the switch is fully turned off. This feedback allows the system to accurately detect the completion of the charging/discharging process and proceed with the next operation at the precise moment isolation is achieved, minimizing unnecessary waiting time while ensuring complete off state.
Solution Approach 2:
The charge pump operates dynamically, adjusting its operation based on the monitoring feedback. When a switch needs to be turned off, the charge pump actively charges the capacitance to the required negative voltage level. When switching is complete and the voltage needs recovery, the charge pump quickly recharges the node. This dynamic operation optimizes both isolation quality and switching speed.
3Reliability
If one switch is turned off before another is turned on, then feedback loops are prevented, but system response time is delayed
Solution Approach 1:
The load monitor continuously monitors the negative voltage node and asserts the break done signal in advance when the voltage reaches the predetermined level. This preliminary assertion of the break done signal allows the switch driver to immediately activate the next switch as soon as it receives the activation signal, without waiting for additional confirmation, thus minimizing the delay while ensuring proper sequencing.
Solution Approach 2:
The load monitor provides real-time feedback on the voltage level at the negative voltage node. This feedback mechanism allows the system to detect when the negative voltage has been successfully established or recovered, and use this information to control the timing of switch activation, ensuring proper sequencing and avoiding conflicts.
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 solution ensures that switches are fully turned off before being activated, preventing conflicts and maintaining system stability by quickly recovering the negative voltage node, thus enabling efficient and conflict-free switching operations.
Implementation Method 1
The charge pump may be configured to drive a negative voltage node to a predetermined negative voltage level
Implementation Method 2
The low threshold switches, however, may have significant capacitance that must be charged or discharged before the switch fully turns off
Data Source
AI summary
A switch activation system including a charge pump, a load monitor, and a switch driver. The charge pump drives a negative voltage node to a predetermined negative voltage level. The load monitor monitors the charge pump and to assert a break done signal after the charge pump begins driving the negative voltage back to the predetermined negative voltage level after being increased. The switch driver turns on a first electronic switch in response to assertion of a corresponding activation signal and assertion of the break done signal. The break done signal is asserted only after electronic switches being turned off are fully turned off to avoid conflict. The charge pump operates at a frequency based on a difference between a voltage level of the negative voltage node and the predetermined negative voltage level to drive the negative voltage node back to its predetermined level within a predetermined period of time.