High voltage integrated Miller capacitor feedback circuit
First Claim
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1. An expansion card comprising:
- a printed wiring substrate including a connector to receive an input voltage and control circuits; and
an integrated Miller compensation circuit to generate a first voltage for said control circuits whose slew rate is lower than the slew rate of said input voltage, said compensation circuit comprising;
an output voltage node which rises to said first voltage;
an integrated voltage divider configured to attenuate the first voltage to provide a second voltage at a first internal node;
an integrated thin-film capacitor electronically coupled between the first internal node and an internal feedback node.
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Abstract
A circuit for controlling an electronic semiconductor switching device to limit the in-rush current when an expansion board is plugged into an electronic system. An integrated thin-film capacitor is used in a high-voltage feedback circuit by attenuating the output voltage, which can be substantially greater than the breakdown voltage of the capacitor, with an integrated voltage divider. An adequate slew rate is obtained using a low capacitance by providing a high-impedance internal feedback node that is coupled to the gate of a power FET with a voltage buffer.
30 Citations
19 Claims
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1. An expansion card comprising:
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a printed wiring substrate including a connector to receive an input voltage and control circuits; and
an integrated Miller compensation circuit to generate a first voltage for said control circuits whose slew rate is lower than the slew rate of said input voltage, said compensation circuit comprising;
an output voltage node which rises to said first voltage;
an integrated voltage divider configured to attenuate the first voltage to provide a second voltage at a first internal node;
an integrated thin-film capacitor electronically coupled between the first internal node and an internal feedback node. - View Dependent Claims (2, 3)
a current source configured to provide a current to the internal feedback node; - and
a voltage buffer amplifier having an input coupled to the internal feedback node.
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4. An expansion card comprising:
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a printed wiring substrate including a connector to receive an input voltage and control circuits; and
an integrated Miller compensation circuit to generate a first voltage for said control circuits whose slew rate is lower than the slew rate of said input voltage, said compensation circuit comprising;
an output voltage node which rises to said first voltage;
an integrated voltage divider configured to attenuate the first voltage to provide a second voltage at a first internal node;
an integrated thin-film capacitor electronically coupled between the first internal node and an internal feedback node;
an integrated current source configured to provide current to the internal feedback node; and
an integrated voltage buffer amplifier having a buffer input electronically coupled to the internal feedback node and a buffer output electronically coupled to an electronic semiconductor switch control node. - View Dependent Claims (5, 6, 7, 8, 9, 10)
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11. An expansion card comprising:
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a printed wiring substrate including a connector to receive an input voltage and control circuits; and
an integrated Miller compensation circuit to generate a first voltage for said control circuits whose slew rate is lower than the slew rate of said input voltage, said compensation circuit comprising;
an output voltage node which rises to said first voltage having an absolute value of between about 30-100 Volts;
an integrated voltage divider configured to attenuate the first voltage to provide a second voltage at a first internal node;
an integrated thin-film capacitor having a breakdown voltage less than the first voltage and greater than the second voltage and a capacitance less than about 50 picofarads, and electronically coupled between the first internal node and an internal feedback node having a feedback node impedance greater than about 1000 Mohms;
an integrated current source configured to provide current to the internal feedback node; and
an integrated voltage buffer amplifier having a buffer input electronically coupled to the internal feedback node and a buffer output electronically coupled to an electronic semiconductor switch control node.
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12. An expansion card comprising:
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a printed wiring substrate including a connector to receive an input voltage and control circuits; and
an electronic circuit to generate a first voltage for said control circuits whose slew rate is lower than the slew rate of said input voltage, said compensation circuit comprising;
an electronic semiconductor switching device having an input port, a control port, and an output port;
a voltage divider configured to attenuate said first voltage at the output port to a second voltage at a first internal node;
a thin-film capacitor electronically coupled between the first internal node and an internal feedback node;
a current source configured to provide current to the internal feedback node; and
a voltage buffer amplifier having a buffer input electronically coupled to the internal feedback node and a buffer output electronically coupled to the control port, wherein at least the thin-film capacitor, the internal feedback node, the current source, and the voltage buffer amplifier are integrated on a semiconductor chip. - View Dependent Claims (13, 14, 15)
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16. A method for operating a Miller feedback circuit, the method comprising:
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connecting an expansion card into a computer bus to receive an input voltage;
providing an output voltage to an output node from said input voltage;
attenuating the output voltage to a feedback voltage;
applying the feedback voltage across a capacitor to an internal feedback node, wherein an input of an integrated operational amplifier is coupled to the internal feedback node.
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17. A method for operating a Miller feedback circuit, the method comprising:
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connecting an expansion card into a computer bus to receive an input voltage;
providing an output voltage to an output node from said input voltage;
attenuating the voltage to a feedback voltage;
applying the feedback voltage across a capacitor to an internal feedback node;
providing a first current to the internal feedback node from a current source; and
buffering the voltage at the internal feedback node to provide a second voltage at a control node. - View Dependent Claims (18, 19)
providing said input voltage to an input node of an electronic semiconductor switching device; - and
turning the electronic semiconductor switching device at least partially on.
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19. The method of claim 17 further comprising a step, between the providing an input voltage step and the turning the electronic semiconductor switching device at least partially on step, of waiting a selected period of time.
Specification