Method and apparatus switching a semiconductor switch with a multi-state drive circuit
First Claim
1. A circuit comprising:
- a semiconductor switch adapted to switch between first and second states, wherein the first state is one of an off state or an on state, wherein the second state is an other one of the off state or the on state;
a plurality of drive circuits coupled to the semiconductor switch, the plurality of drive circuits having a drive circuit impedance and coupled to provide a plurality of drive signals to switch the semiconductor switch from the first state to the second state; and
a selector circuit coupled to the semiconductor switch through a connection to sense the semiconductor switch, the selector circuit further coupled to each of the plurality of drive circuits to select in response to the sensing of the semiconductor switch through the connection the drive circuits that provide the plurality of drive signals to the semiconductor switch to reduce the drive circuit impedance as the semiconductor switch switches from the first state to the second state.
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Abstract
A method and an apparatus for implementing a semiconductor switch multi-stage drive circuit. The disclosed method and an apparatus reduce losses in a semiconductor switch when it is turned from an off state to an on state or from an on state to an off state. The reduction in losses is achieved without influencing the dv/dt across the semiconductor switch during a first time period while the semiconductor switch is switching. This reduction in losses is therefore achieved with very little increase in the noise generated due to rapid dv/dt during the first time period when the semiconductor switch is switching. The configuration of the circuitry to achieve this reduction in switching losses is such that benefits are less sensitive to manufacturing tolerances and temperature effects than alternative semiconductor switch drive schemes to achieve similar results.
49 Citations
20 Claims
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1. A circuit comprising:
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a semiconductor switch adapted to switch between first and second states, wherein the first state is one of an off state or an on state, wherein the second state is an other one of the off state or the on state; a plurality of drive circuits coupled to the semiconductor switch, the plurality of drive circuits having a drive circuit impedance and coupled to provide a plurality of drive signals to switch the semiconductor switch from the first state to the second state; and a selector circuit coupled to the semiconductor switch through a connection to sense the semiconductor switch, the selector circuit further coupled to each of the plurality of drive circuits to select in response to the sensing of the semiconductor switch through the connection the drive circuits that provide the plurality of drive signals to the semiconductor switch to reduce the drive circuit impedance as the semiconductor switch switches from the first state to the second state. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A method, comprising:
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selectively driving a semiconductor switch with a first drive signal from a drive circuit to switch from a first state to a second state, wherein the first state comprises one of an off state or an on state, wherein the second state comprises an other one of the off state or the on state; sensing the semiconductor switch through a connection; and selectively driving the semiconductor switch with a second drive signal from the drive circuit in response to the sensing of the semiconductor switch through the connection to switch the semiconductor switch from the first state to the second state to reduce a drive circuit impedance after the semiconductor switch has already begun to switch from the first state to the second state. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20)
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Specification