Circuit and method for fast switching of a current mirror with large MOSFET size
View Patent ↗The present invention discloses a fast switching current mirror circuit and method for generating fast switching current. The circuit and method for fast switching of a current mirror with large MOSFET size will save space and current consumption.
1. A circuit for providing a switched current comprising:
a first current mirror having a power terminal coupled to a source of supply voltage, an input, and an output;
a second current mirror having an input for receiving an input current, a first output coupled to the output of the first current mirror, a second output coupled to the input of the first current mirror, and a power terminal coupled to ground;
a draining module having an input coupled to the output of the first current mirror, a first output coupled to the input of the first current mirror, and a second output coupled to ground; and
an MOS output transistor having a gate coupled to the input of the first current mirror through a first switch and coupled to the source of supply voltage through a second switch, a first current terminal coupled to the source of supply voltage, and a second current terminal for providing the switched current.
2. The circuit of claim 1 wherein the first current mirror comprises a PMOS current mirror.
3. The circuit of claim 1 wherein the first current mirror comprises a first transistor one-thousandth the size of the output transistor.
4. The circuit of claim 3 wherein the first current mirror comprises a second transistor one-thousandth the size of the output transistor.
5. The circuit of claim 1 wherein the second current mirror comprises an NMOS current mirror.
6. The circuit of claim 1 wherein the draining module comprises:
an inverter having an input coupled to the input of the draining module, and an output; and
a transistor having a gate coupled to the output of the inverter, a first current output coupled to the first output of the draining module, and a second current output coupled to the second output of the draining module.
7. The circuit of claim 6 wherein the transistor comprises an NMOS transistor.
8. The circuit of claim 1 wherein the input current is equal to 50 μA.
9. The circuit of claim 1 wherein the switched current is switched to 50 mA.
10. The circuit of claim 1 wherein the first current mirror comprises a unity gain current mirror.
11. The circuit of claim 1 wherein the second current mirror comprises a unity gain current mirror.
12. A circuit for providing a switched current comprising:
a first current mirror;
a second current mirror for receiving an input current having first and second outputs coupled to the first current mirror;
an inverter having an input coupled to the first output of the second current mirror, and an output;
a first transistor having a gate coupled to the output of the inverter, a drain coupled to the second output of the second current mirror, and a source coupled to ground; and
a second transistor having a gate coupled to an input of the first current mirror through a first switch and coupled to a source of supply voltage through a second switch, a source coupled to the source of supply voltage, and a drain for providing the switched current, wherein the second transistor comprises an MOS transistor.
13. A circuit for providing a switched current comprising:
a first current mirror;
a second current mirror for receiving an input current having first and second outputs coupled to the first current mirror;
an inverter having an input coupled to the first output of the second current mirror, and an output;
a draining transistor having a gate coupled to the output of the inverter, a drain coupled to the second output of the second current mirror, and a source coupled to ground; and
a switched MOS output transistor having a gate coupled to an input of the first current mirror, a source coupled to a source of supply voltage, and a drain for providing the switched current.