Poly-resistor, and linear amplifier
View Patent ↗The present invention provides a poly-resistor with an improved linearity. Majority charge carrier wells are provided under the poly-strips and are biased in such way that the non-linearity of the resistor is reduced. Further, when such poly-resistors are used in amplifier circuits, the gain of the amplifier remains constant against the poly-depletion effect.
1. A poly-resistor, comprising:
a first region wherein the first region is characterized as semiconductive or conductive;
a resistive strip providing a resistive connection between a first resistor contact and a second resistor contact; said resistive strip extending over at least a part of said first region;
a dielectric layer isolating said first region from said resistive strip; and
a bias source connected to said first region, for biasing said first region to a voltage which lies between a voltage at the first resistor contact and a voltage at the second resistor contact, said bias source including:
a second resistive strip providing a resistive connection between a third resistor contact at which a first voltage can be applied and a forth resistor contact at which a second voltage can be applied; and
a conductive path from said second resistive strip to said first region, for biasing said first region with a bias voltage between said first voltage and said second voltage.
2. A poly-resistor as claimed in claim 1 , wherein said bias source includes a conductive path from said resistive strip to said first region.
3. A poly-resistor as claimed in claim 2 , wherein said conductive path includes: at least one passage through said dielectric layer that electrically connects a position at said resistive strip to said first region, said conductive path for biasing said first region to a voltage of said position.
4. A poly-resistor as claimed in claim 3 , wherein when said poly-resistor is in use, a first change in resistivity occurs in a part of said strip between said position and said first resistor contact and a second change in resistivity occurs in a part of said strip between said position and said second resistor contact, said second change at least partially compensating said first change.
5. A poly-resistor as claimed in claim 3 , wherein a distance between said position and said first resistor contact is substantially equal to a distance between said position and said second resistor contact.
6. A poly-resistor as claimed in claim 1 , wherein the first region is provided with an n-type doping and a material below the first region is provided with a p-type doping or vice versa.
7. A poly-resistor as claimed in claim 1 , wherein said dielectric layer is a shallow trench isolation region extending over said first region.
8. A poly-resistor as claimed in claim 1 , wherein said resistive strip is a poly-silicon strip.
9. A poly-resistor as claimed in claim 1 , wherein the sheet resistance of the poly-resistor is in a range of 10Ω to 10 kΩ per square.
10. A poly-resistor as claimed in claim 1 , wherein said resistive strip has a rectangular shape and wherein said first resistor contact is provided at a first end of the rectangular shape and the second resistor contact is provided at a second end of the rectangular shape, opposite to the first edge.
11. A poly-resistor as claimed in claim 10 , wherein a conductive element is provided, in a direction from the first end to the second end, in the middle of said rectangular shape.
12. A poly-resistor as claimed in claim 11 , wherein said conductive element separates said resistive strip into a first part and a second part and is connected to said first region.
13. A poly-resistor as claimed in claim 1 , including a substrate and, optionally at least one intermediate layer between said substrate and said dielectric layer, and wherein said first region is provided in said substrate and/or at least one of said at least one intermediate layer.
14. An integrated circuit including a poly-resistor as claimed in claim 1 .
15. An amplifier circuit comprising:
an input for receiving input signal;
an amplifying stage including a stage input and a stage output;
a poly-resistor connected to said stage input and/or said output: and
an output connected to said stage output, for outputting an amplified signal; wherein the poly-resistor is a poly-resistor as claimed in claim 1 .
16. A poly-resistor as claimed in claim 4 , wherein a distance between said position and said first resistor contact is substantially equal to a distance between said position and said second resistor contact.
17. A poly-resistor as claimed in claim 2 , wherein the first region is provided with an n-type doping and a material below the first region is provided with a p-type doping or vice versa.
18. A poly-resistor as claimed in claim 7 wherein said resistive strip is a poly-silicon strip.