Bi-directional Switch Control Circuitry for Medical Stimulators
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Solution Overview
Problem
State-of-the-art medical stimulators face challenges in reducing power consumption due to the high number of switches in cross-point switch matrices, which limits energy storage capacity and increases power dissipation, especially in high-voltage IC technologies where CMOS switches have limited gate-to-source voltage, affecting the efficiency of bidirectional switches in medical applications.
Innovation Solution
A control circuitry for bidirectional switches that utilizes an energy storage element only coupled to the supply voltage when the switch is in the off state, generating a control voltage independent of the supply voltage, reducing static power consumption by charging the energy storage element only when the switch is off and using it to power the control circuit, thus minimizing power dissipation during switching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the number of switches in cross-point switch matrix is increased to improve therapeutic efficacy through field steering and accurate sensing, then stimulation and sensing precision is improved, but power consumption increases and available volume for energy storage decreases
Solution Approach 1:
The energy storage element is periodically charged from the supply voltage only during specific time intervals when the bi-directional switch is in the off state. This periodic charging action allows the control circuit to accumulate energy in discrete steps, enabling the system to support a larger number of switches without proportionally increasing continuous power consumption, thus resolving the contradiction between sensing precision and power usage.
2Use of energy by moving object
If integrated CMOS switches in high-voltage IC technology are used to meet low-power requirements, then power consumption is reduced, but gate-to-source voltage is limited to a few volts compared to much higher drain-to-source voltage
Solution Approach 1:
The energy storage element acts as an intermediary between the supply voltage and the control circuit. It stores energy when charged from the supply voltage and then provides this stored energy to the control circuit, enabling the control circuit to generate control voltages with a wider range than the limited gate-to-source voltage of CMOS switches. This intermediary mechanism allows the system to maintain low power consumption while expanding the voltage control range for ease of operation.
3Reliability
If energy storage element is continuously coupled to supply voltage to power control circuit, then control circuit has continuous power supply, but static power consumption increases
Solution Approach 1:
The energy storage element is periodically charged from the supply voltage only during specific time intervals when the bi-directional switch is in the off state, rather than maintaining continuous coupling. This periodic charging provides the control circuit with sufficient stored energy to operate during intervals when not charging, thereby maintaining power supply reliability while eliminating continuous static power consumption from the supply voltage.
4Device complexity
If control voltage level is dependent on supply voltage, then circuit design is simplified, but power dissipation increases during switching
Solution Approach 1:
The energy storage element serves as an intermediary that decouples the control voltage level from the supply voltage. By storing energy from the supply voltage and providing it to the control circuit, the energy storage element enables the control circuit to generate control voltages independent of the supply voltage level. This independence reduces power dissipation during switching while the energy storage element manages the voltage level transformation, balancing circuit complexity with energy efficiency.
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 approach significantly reduces power consumption by eliminating static power loads and dynamic power dissipation during switching, enhancing the efficiency of bidirectional switches in medical stimulators and allowing for more efficient energy management in low-power medical devices.
Implementation Method 1
a control circuitry (102, 214, 222) for controlling a bi-directional switch (132, 212, 220)... comprising an energy storage element (102, 214, 222)... The coupling means (101, 201) couples the energy storage element (102, 214, 222) to a supply voltage (Vsup) for charging energy storage element (102, 214, 222)
Data Source
AI summary
A control circuitry (134) and a method for controlling a bi-directional switch (132) is provided. The bi-directional switch (132) having a control terminal (130) for receiving a control voltage (124) to control an on state and an off state of the bi-directional switch (132) and at least one semiconductor switch in a bi-directional main current path. The control circuitry (134) comprises an energy storage element (102), a coupling means (101) to couple the energy storage element (102) to a supply voltage to charge the energy storage element (102), and a control circuit (108) configured to receive power from the energy storage element (102) and pendent of the supply voltage when the emergency storage element (102) is not coupled to the supply voltage. The coupling means (101) is configured for only coupling the energy storage element (102) to the supply voltage when the bi-directional switch (132) is in the off state.