Precision oscillators that use imprecise components

1. An oscillator comprising:

a trim-capable current source that comprises:

a trimmable resistor;

a trimmable current component;

a mirror transistor coupled to mirror a current through the trimmable resistor; and

a trim component coupled to the mirror transistor and operable to:

measure the current through the trimmable resistor; and

determine, based on the current through the trimmable resistor, an offset between a resistance of the trimmable resistor and a target resistance, wherein the trim-capable current source is operable to change the resistance of the trimmable resistor in response to the offset;

a comparator comprising a first input terminal that couples to the trim-capable current source and a second input terminal that couples to a reference voltage source;

a switch coupled to the first input terminal and the trim-capable current source; and

a trim-capable capacitor coupled to the switch, wherein the switch is coupled between the trim-capable capacitor and the trim-capable current source, and wherein the first input terminal of the comparator is electrically disconnected from the trim-capable capacitor when the switch is in a non-conductive state.

2. The oscillator of claim 1 , further comprising:

a second switch coupled to the first input terminal and the trim-capable current source; and

a second trim-capable capacitor coupled to the first input terminal, where the second switch is positioned between the trim-capable capacitor and the trim-capable current source.

3. The oscillator of claim 1 , further comprising a flip flop component, wherein an output terminal of the comparator is coupled to an input of the flip flop component.

4. The oscillator of claim 1 , wherein the trimmable resistor includes a resistor digital-to-analog circuit (RDAC) and the trimmable current component includes a current digital-to-analog circuit (IDAC).

5. The oscillator of claim 1 , wherein the trim-capable current source comprises a second trimmable resistor.

6. The oscillator of claim 5 , wherein the trimmable resistor and the second trimmable resistor are imprecise resistors.

7. The oscillator of claim 1 , wherein the trim-capable capacitor is a capacitor digital-to-analog circuit (CDAC).

8. An oscillator comprising:

a trim-capable current source that comprises:

a trimmable resistor;

a trimmable current component;

a mirror transistor coupled to mirror a current through the trimmable resistor; and

a trim component coupled to the mirror transistor and operable to:

measure the current through the trimmable resistor; and

determine, based on the current through the trimmable resistor, an offset between a resistance of the trimmable resistor and a target resistance, wherein the trim-capable current source is operable to change the resistance of the trimmable resistor in response to the offset;

a first comparator comprising a first input terminal that couples to the trim-capable current source and a second input terminal that couples to a reference voltage source;

a first switch coupled to the first input terminal and the trim-capable current source;

a first trim-capable capacitor coupled to the first switch, wherein the first switch is coupled between the first trim-capable capacitor and the trim-capable current source;

a second comparator comprising a third input terminal and a fourth input terminal, wherein the fourth input terminal is coupled to the reference voltage source; and

a second switch coupled between the trim-capable current source and the third input terminal of the second comparator.

9. The oscillator of claim 8 , further comprising a second trim-capable capacitor coupled to the third input terminal.

10. The oscillator of claim 8 , further comprising a flip flop, wherein an output terminal of the first comparator is coupled to an input of the flip flop and an output terminal of the second comparator is coupled to a second input of the flip flop.

11. An oscillator comprising:

a trim-capable current source configured to:

measure a current through a variable resistor that affects a first portion current of a capacitor charging current generated from the trim-capable current source;

determine, from the current, a resistance of the variable resistor;

determine an offset between the resistance of the variable resistor and a target resistance;

trim, based on the offset, the resistance of the variable resistor; and

trim the first portion current to adjust a proportion of the first portion current in the capacitor charging current generated from the trim-capable current source;

a comparator comprising a first input terminal that couples to the trim-capable current source and a second input terminal that couples to a reference voltage source; and

a trim-capable capacitor coupled to the first input terminal, wherein the trim-capable capacitor is configured to perform capacitor switching that controls a charge time of the trim-capable capacitor.

12. The oscillator of claim 11 , wherein the variable resistor comprises a resistor digital-to-analog circuit (RDAC) and the trim-capable current source comprises a current digital-to-analog circuit (IDAC).

13. The oscillator of claim 12 , wherein the RDAC includes a plurality of poly-resistors.

14. The oscillator of claim 11 , wherein the trim-capable current source is configured to generate a second portion current of the capacitor charging current that combines with the first portion current to form the capacitor charging current.

15. The oscillator of claim 11 , wherein the trim-capable capacitor is a capacitor digital-to-analog circuit (CDAC).

16. The oscillator of claim 15 , wherein the CDAC includes a 10 bit split-CDAC array.

17. A method comprising:

measuring a current through a trimmable resistor of an oscillator, wherein the trimmable resistor affects a first portion current of a capacitor charging current generated from a trim-capable current source of the oscillator;

determining an offset between the current through the trimmable resistor and a target resistance;

trimming the resistance of the trimmable resistor;

trimming the first portion current to adjust a proportion of the first portion current in the capacitor charging current generated from the trim-capable current source, wherein the capacitor charging current is a combination of the first portion current and a second portion current; and

trimming a trim-capable capacitor to perform capacitor switching that controls a charge time of the trim-capable capacitor.

18. The method of claim 17 , wherein the trimmable resistor includes a resistor digital-to-analog circuit (RDAC) to trim the resistance and the trim-capable current source includes a current digital-to-analog circuit (IDAC) to trim the first portion current that adjusts the proportion of the first portion current in the capacitor charging current.

19. The method of claim 17 , wherein the trim-capable capacitor is a capacitor digital-to-analog circuit (CDAC).

20. The method of claim 19 , wherein the CDAC includes a 10 bit split-CDAC array.