Stacked cascode current source
View Patent ↗Apparatus are provided for a stacked cascode current source. An apparatus is provided for an electrical device comprising an input node and an output node. A first transistor stack is coupled to the input node. The first transistor stack includes a first transistor and a second transistor. A drain terminal and a gate terminal of the first transistor are coupled to the input node. A drain terminal of the second transistor is coupled to a source terminal of the first transistor and a gate terminal of the second transistor is coupled to the input node. A second transistor stack coupled to the first transistor stack and the output node to create a current mirror for the first transistor stack.
1. A stacked cascode current source comprising:
an input node;
an output node;
a first transistor having a first drain terminal coupled to the input node, a first gate terminal coupled to the input node, and a first source terminal;
a second transistor having a second drain terminal coupled to the first source terminal, a second gate terminal coupled to the input node, and a second source terminal;
a third transistor having a third drain terminal coupled to the second source terminal, and a third gate terminal coupled to the first source terminal;
a fourth transistor having a fourth drain terminal coupled to the output node, a fourth gate terminal coupled to the first gate terminal, and a fourth source terminal;
a fifth transistor having a fifth drain terminal coupled to the fourth source terminal, a fifth gate terminal coupled to the second gate terminal, and a fifth source terminal; and
a sixth transistor having a sixth drain terminal coupled to the fifth source terminal, and a sixth gate terminal coupled to the third gate terminal.
2. The stacked cascode current source of claim 1 , the third transistor having a third source terminal and the sixth transistor having a sixth source terminal, wherein the stacked cascode current source further comprises:
a seventh transistor having a seventh drain terminal coupled to the third source terminal, and a seventh gate terminal coupled to the second source terminal; and
an eighth transistor having an eighth drain terminal coupled to the sixth source terminal, and an eighth gate terminal coupled to the seventh gate terminal.
3. The stacked cascode current source of claim 2 , the seventh transistor having a seventh source terminal, the eighth transistor having an eighth source terminal, wherein the seventh source terminal and the eighth source terminal are coupled to establish a reference voltage potential.
4. The stacked cascode current source of claim 1 , the third transistor having a third source terminal, the sixth transistor having a sixth source terminal, wherein the third source terminal is coupled to the sixth source terminal to establish a reference voltage potential.
5. The stacked cascode current source of claim 1 , further comprising a source coupled to the input node, the source being configured to provide a reference current to the input node.
6. The stacked cascode current source of claim 5 , wherein current at the output node is substantially equal to the reference current.
7. The stacked cascode current source of claim 6 , wherein the current at the output node is substantially equal to a fixed ratio of the reference current.
8. The stacked cascode current source of claim 6 , wherein the source comprises a resistor coupled electrically in series between a voltage supply and the input node.
9. The stacked cascode current source of claim 6 , further comprising a load coupled between a voltage supply and the output node, wherein current through the load is substantially equal to the reference current.
10. An electrical device comprising:
an input node;
an output node;
a first transistor pair having a first transistor, a second transistor, and a first common gate node coupled to the input node, wherein a drain terminal of the first transistor is coupled to the input node, and a drain terminal of the second transistor is coupled to the output node;
a second transistor pair having a second common gate node coupled to the input node, wherein the first transistor pair and the second transistor pair are stacked, the second transistor pair including a third transistor having a drain terminal coupled to a source terminal of the first transistor and a gate terminal coupled to the second common gate node; and
a third transistor pair having a third common gate node coupled to the source terminal of the first transistor, wherein the second transistor pair and the third transistor pair are stacked, the third transistor pair including a fourth transistor having a drain terminal coupled to a source terminal of the third transistor and a gate terminal coupled to the third common gate node.
11. The electrical device of claim 10 , wherein the electrical device further comprises a fourth transistor pair having a fourth common gate node coupled to the drain terminal of the third transistor, wherein the third transistor pair and the fourth transistor pair are stacked.
12. The electrical device of claim 11 , wherein the fourth transistor pair has a common source node configured to establish a reference ground.
13. The electrical device of claim 10 , wherein the third transistor pair has a common source node configured to establish a reference ground.
14. The electrical device of claim 10 , further comprising a current source coupled to the input node, the current source being configured to provide a reference current to the input node.
15. The electrical device of claim 14 , wherein current at the output node is substantially equal to a fixed ratio of the reference current.
16. An electrical device comprising:
an input node;
an output node;
a first transistor stack coupled to the input node, the first transistor stack comprising a first transistor, a second transistor, and a third transistor, wherein:
a drain terminal of the first transistor is coupled to the input node;
a gate terminal of the first transistor is coupled to the input node;
a drain terminal of the second transistor is coupled to a source terminal of the first transistor;
a gate terminal of the second transistor is coupled to the input node;
a drain terminal of the third transistor is coupled to a source terminal of the second transistor; and
a gate terminal of the third transistor is coupled to the source terminal of the first transistor; and
a second transistor stack coupled to the first transistor stack and the output node to create a current mirror for the first transistor stack, the second transistor stack comprising a fourth transistor, a fifth transistor, and a sixth transistor, wherein:
a drain terminal of the fourth transistor is coupled to the output node;
a gate terminal of the fourth transistor is coupled to the gate terminal of the first transistor;
a drain terminal of the fifth transistor is coupled to a source terminal of the fourth transistor;
a gate terminal of the fifth transistor is coupled to the gate terminal of the second transistor;
a drain terminal of the sixth transistor is coupled to a source terminal of the fifth transistor; and
a gate terminal of the sixth transistor is coupled to the gate terminal of the third transistor.
17. The electrical device of claim 16 , wherein the second transistor stack comprises a plurality of stacked transistors having gate terminals coupled to gate terminals of the first transistor stack.
18. The electrical device of claim 16 , further comprising a source coupled to the input node, the source being configured to provide a reference current to the input node, wherein current at the output node is substantially equal to the reference current.
19. The electrical device of claim 16 , wherein the first transistor stack and the second transistor stack have a common source node configured to establish a reference voltage potential.