Current drive circuit reducing VDS dependency
AssigneeRohm Co., Ltd.
InventorsIsao Yamamoto, Koichi Miyanaga
Life of this patent
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Abstract
A first transistor is provided in a first route and a second transistor is provided in a second route, the first route and the second route constituting a current mirror circuit. The sources of the transistors are grounded. In order to match VDS of the first transistor and that of the second transistor match each other, there are provided an operational amplifier receiving the drain voltages of the transistors, and a third transistor having a gate thereof connected to the output of the operational amplifier. The third transistor is provided in the first route. As a result, the current fed to the third transistor is controlled so that VDS of the first transistor and that of the second transistor match each other.
Claims5
A current drive circuit comprising:
- a first route feeding a reference current;
- a second route including a target load and feeding a drive current to the load;
- a first resistor and a third resistor provided in series in said first route;
- a second resistor and a fourth resistor provided in series in said second route;
- a first element which is connected to said third resistor in parallel and, upon transition from an initial state to another state, maintains said another state;
- a second element which is connected to said fourth resistor in parallel and, upon transition from an initial state to another state, maintains said another state;
- and
- an operational amplifier having two inputs thereof connected to an end of said first resistor and an end of said second resistor, respectively, wherein
- a transistor is provided in said second route and a gate of the transistor is connected to an output of said operational amplifier.
Dependencies are inferred from the claim text.