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US 6,674,275 B2Granted
Current source utilizing a transconductance amplifier and a lowpass filter
AssigneeSTMicroelectronics S.r.l.
InventorSaul Darzy
Life of this patent
Estimating the term…
Abstract
A current source circuit is described for generating control current. The circuit is capable of generating a very accurate reference current and in particular dealing with the problem which can arise from injected noise. A feedback loop is implemented to reject the charge injection noise.
Claims4
A current source for generating a control current comprising:
- a reference current generator having a first output impedance and connected to supply a substantially constant reference current to a circuit node;
- a control current generator having a second output impedance and connected to supply said control current to said circuit node;
- whereby an input voltage is generated at said circuit node based on the substantially constant reference current, the control current and the first and second output impedances;
- a filter circuit connected to said circuit node and arranged to filter said input voltage;
- and
- an amplifier connected to receive the filtered input voltage and arranged to control the level of said control current in dependence on the filtered input voltage.
3 more elements
A current source for generating a control current comprising:
- a reference current generator having a first output impedance and connected to supply a reference current to a circuit node;
- a control current generator having a second output impedance and connected to supply said control current to said circuit node;
- whereby an input voltage is generated at said circuit node based on the reference current, the control current and the first and second output impedances;
- a filter circuit connected to said circuit node and arranged to filter said input voltage;
- and
- an amplifier connected to receive the filtered input voltage and arranged to control the level of said control current in dependence on the filtered input voltage;
- wherein the amplifier comprises a transistor having a source connected to a resistive component and a gate connected to receive the filtered input voltage.
4 more elements
A current source for generating a control current comprising:
- a reference current generator having a first output impedance and connected to supply a reference current to a circuit node;
- a control current generator having a second output impedance and connected to supply said control current to said circuit node;
- whereby an input voltage is generated at said circuit node based on the reference current, the control current and the first and second output impedances;
- a filter circuit connected to said circuit node and arranged to filter said input voltage;
- and
- an amplifier connected to receive the filtered input voltage and arranged to control the level of said control current in dependence on the filtered input voltage;
- wherein the control current generator comprises a current source connected to a current mirror circuit which supplies said control current to said circuit node.
4 more elements
A current source for generating a control current comprising:
- a reference current generator having a first output impedance and connected to supply a reference current to a circuit node;
- a control current generator having a second output impedance and connected to supply said control current to said circuit node;
- whereby an input voltage is generated at said circuit node based on the reference current, the control current and the first and second output impedances;
- a filter circuit connected to said circuit node and arranged to filter said input voltage;
- and
- an amplifier connected to receive the filtered input voltage and arranged to control the level of said control current in dependence on the filtered input voltage;
- wherein the filter circuit comprises a resistive component between said circuit node and the amplifier, and a capacitor connected between said resistor and a voltage supply terminal.
4 more elements
Dependencies are inferred from the claim text.