Current source that has a high output impedance and that can be used with low operating voltages
AssigneeInfineon Technologies AG
InventorChristian Paulus
Life of this patent
Estimating the term…
Abstract
An electrical current source with a high output resistance has a current determining transistor and a regulating switch. The regulating switch has an amplifier circuit with transistors and a regulating transistor, and allows the electrical supply to have a high output resistance. To enable the electrical supply to be used at even very low operating voltages, a sourcing circuit is provided, which is used for setting a freely selectable minimal decrease in voltage over the supply. The sourcing circuit has one or more transistors and influences the voltage at the current determining transistor. The output resistance of the electrical source can be further improved by utilizing a correcting circuit that has resistors.
Claims10
A current source having a high output impedance at an output terminal, comprising:
- a current-determining transistor determining an output current, said current-determining transistor having a source terminal, a drain terminal, a gate terminal, and a source-drain voltage;
- a source-follower circuit providing an output signal;
- a control circuit having:
- an output terminal;
- and
- an input connected to said source-follower circuit and receiving said output signal of said source-follower circuit;
- a control transistor connected in series with said current-determining transistor, said control transistor having a source terminal, a drain terminal, and a gate terminal;
- one of said source terminal and said drain terminal of said current-determining transistor being connected with one of said source terminal and said drain terminal of said control transistor and another one of said source terminal and said drain terminal of said current-determining transistor being connected with a pole of a voltage supply;
- an input voltage supplied to said gate terminal of said current-determining transistor for determining a current output by the current source;
- one of said source terminal and said drain terminal of said control transistor being connected with one of said source terminal and said drain terminal of said current-determining transistor and another one of said source terminal and said drain terminal of said control transistor being the output terminal of the current source from which output current is generated by the current source;
- a node between said current-determining transistor and said control transistor defining a potential;
- said gate terminal of said control transistor being connected with said output terminal of said control circuit;
- said control circuit ensuring that said source-drain voltage of said current-determining transistor has and maintains a required value by applying a suitable drive to said control transistor;
- and
- said source-follower circuit having an input receiving said potential between said current-defining transistor and said control transistor.
Dependencies are inferred from the claim text.