Method and algorithm of high precision on-chip global biasing using integrated resistor calibration circuits
View Patent ↗Systems and methods for providing bias currents to multiple analog circuits are disclosed. An integrated circuit comprises a calibration circuit which compares a high tolerance external component to a plurality of internal components manufactured to span the variability of the process, voltage and temperature. The best fitting internal component is communicated to bias circuits which can select an internal component from a local plurality of internal components with matching desired characteristics. In this manner, analog circuits can be locally biased with the tolerance usually associated with a high tolerance external reference component, without the necessity for a local external reference component.
1. An integrated circuit comprising:
a calibration circuit having a first plurality of internal components; and
an analog circuit having a second plurality of internal components,
wherein the calibration circuit compares a value corresponding to each component in the first plurality of internal components to an external reference and selects a best matching selected component in the first plurality of internal components; the calibration circuit communicates the selection of the selected component to the analog circuit; and the analog circuit uses a component in the second plurality of internal components corresponding to the selected component.
2. The integrated circuit of claim 1 , wherein each of the first plurality of internal components is a resistor, each of the second plurality of internal components is a resistor; and the external reference is a high tolerance resistor.
3. The integrated circuit of claim 1 , wherein each of the first plurality of internal components is a high sheet resistance polysilicon resistor, each of the second plurality of internal components is a high sheet resistance polysilicon resistor; and the external reference is a high tolerance resistor.
4. The integrated circuit of claim 1 , wherein each of the first plurality of internal components is a low sheet resistance polysilicon resistor, each of the second plurality of internal components is a low sheet resistance polysilicon resistor; and the external reference is a high tolerance resistor.
5. The integrated circuit of claim 4 , further comprising another analog circuit having a third plurality of internal components, wherein the calibration circuit further comprises a fourth plurality of internal components, and wherein each of the third plurality of internal components and each of the fourth plurality of internal components is a low sheet resistance polysilicon resistor.
6. The integrated circuit of claim 1 , wherein the calibration circuit comprises:
a programmable current bias circuit;
an analog-to-digital converter; and
a digital state engine,
wherein the programmable current bias circuit comprises the first plurality of internal components.
7. The integrated circuit of claim 1 , wherein the programmable current bias circuit comprising:
the first plurality of internal components;
a plurality of switches each coupled to one of the first plurality of internal components;
a digital decoder coupled to the plurality of switches;
a bandgap voltage reference;
a buffer coupled to the bandgap voltage; and
a current mirror coupled to the buffer and to the first plurality of internal components.
8. The integrated circuit of claim 1 , wherein the analog circuit is a current bias circuit.
9. The integrated circuit of claim 1 , wherein the analog circuit is a band gap referenced bias circuits.
10. The integrated circuit of claim 1 , wherein the analog circuit is a low 1/f noise Widlar-based bias circuit.
11. The integrated circuit of claim 1 , wherein the analog circuit is a PTAT bias circuit.
12. The integrated circuit of claim 9 , wherein the PTAT bias circuit comprises:
NPN transistors in a cross coupled configuration;
the second plurality of internal components;
a plurality of switches each coupled to one of the first plurality of internal components;
a digital decoder coupled to the plurality of switches; and
a current mirror coupled to the NPN transistors.
13. A method of providing reference to an analog circuit residing on an integrated circuit comprising:
powering-up the integrating circuit and waiting for the integrated circuit to reach an equilibrium;
comparing an external component to each of a first plurality of internal components by a calibration circuit;
selecting a matching component in the first plurality of internal components by the calibration circuit;
transmitting a label representative of the matching component to the analog circuit;
using a component in a second plurality of internal components, the component corresponding the matching component by the analog circuit;
latching the label; and
powering down the calibration circuit.
14. The method of claim 13 , wherein each of the first plurality of internal components is a resistor, each of the second plurality of internal components is a resistor, and the external reference is a high tolerance resistor.
15. The method circuit of claim 13 , wherein each of the first plurality of internal components is a high sheet resistance polysilicon resistor, each of the second plurality of internal components is a high sheet resistance polysilicon resistor, and the external reference is a high tolerance resistor.
16. The method circuit of claim 13 , wherein each of the first plurality of internal components is a low sheet resistance polysilicon resistor, each of the second plurality of internal components is a low sheet resistance polysilicon resistor, and the external reference is a high tolerance resistor.
17. The method of claim 13 , wherein the analog circuit is a current bias circuit.
18. The method of claim 17 , wherein the analog circuit is a PTAT bias circuit, a band gap referenced bias circuits or a low 1/f noise Widlar-based bias circuit.