High-voltage bulk driver using bypass circuit
AssigneeFairchild Semiconductor Corporation
InventorsJulie Lynn Stultz, Tyler Daigle
Life of this patent
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Abstract
This application discusses, among other things, apparatus and methods for driving the bulk of a high-voltage transistor using transistors having gates with low-voltage ratings. In an example, a bulk driver can include an output configured to couple to bulk of a high-voltage transistor, a pick circuit configured to couple the output to an input voltage at an input terminal of the high-voltage transistor or an output voltage at the output terminal of the high-voltage transistor when the high-voltage transistor is in a high impedance state, and a bypass circuit configured to couple the output of the bulk driver to the output voltage when the high-voltage transistor is in a low impedance state.
Claims21
A bulk driver for a high-voltage transistor, the high-voltage transistor configured to couple an input terminal with an output terminal in a low-impedance state and to isolate the input terminal from the output terminal in a high impedance state, the bulk driver comprising:
- an output configured to couple to a bulk of the high-voltage transistor;
- a pick circuit configured to couple the bulk of the high-voltage transistor to an input voltage at the input terminal or an output voltage at the output terminal when the high-voltage transistor is in the high impedance state;
- and
- a bypass circuit configured to couple the output of the bulk driver to the output voltage when the high-voltage transistor is in the low impedance state.
A method of driving bulk of a high-voltage field effect transistor (FET), the high-voltage FET configured to couple an input terminal with an output terminal in a low-impedance state and to isolate the input terminal from the output terminal in a high impedance state, the method comprising:
- receiving an low-voltage enable signal at a bulk driver circuit, the low voltage enable signal configured to establish the high-voltage FET in the low impedance state;
- receiving the low voltage enable signal at a gate node of a bypass circuit;
- and
- coupling the output terminal of the high-voltage FET to a bulk of the high-voltage FET using first and second lateral diffused transistors of the bypass circuit coupled in series between the output node and the bulk of the high-voltage FET.
A high-voltage transistor switch system comprising
- A high-voltage field effect transistor configured to couple an input terminal with an output terminal in a low-impedance state and to isolate the input terminal from the output terminal in a high impedance state;
- and
- a bulk driver configured to drive a bulk of the high-voltage field effect transistor, the bulk driver comprising:
- an output configured to couple to the bulk of the high-voltage transistor;
- a pick circuit configured to couple the bulk of the high-voltage transistor to an input voltage at the input terminal or an output voltage at the output terminal when the high-voltage transistor is in the high impedance state;
- and
- a bypass circuit configured to couple the output of the bulk driver to the output voltage when the high-voltage transistor is in the low impedance state.
Dependencies are inferred from the claim text.