Apparatus for digitally controlled oscillators and associated methods
An apparatus includes a digitally controlled oscillator (DCO), which includes an inductor coupled in series with a first capacitor. The DCO further includes a second capacitor coupled in parallel with the series-coupled inductor and first capacitor, a first inverter coupled in parallel with the second capacitor, and a second inverter coupled back-to-back to the first inverter. The DCO further includes a digital-to-analog-converter (DAC) to vary a capacitance of the first capacitor.
1. An apparatus, comprising:
a digitally controlled oscillator (DCO) comprising:
an inductor coupled in series with a first capacitor;
a second capacitor coupled in parallel with the series-coupled inductor and first capacitor, wherein a capacitance value of the first capacitor and a capacitance value of the second capacitor are overlapping;
a first inverter coupled in parallel with the second capacitor;
a second inverter coupled back-to-back to the first inverter; and
a digital-to-analog-converter (DAC) to vary a capacitance of the first capacitor.
2. The apparatus according to claim 1 , wherein the DAC varies a capacitance of the first capacitor in response to a first set of bits.
3. The apparatus according to claim 2 , wherein the DAC varies a capacitance of the second capacitor in response to a second set of bits.
4. The apparatus according to claim 1 , wherein capacitance value of the first capacitor and the capacitance value of the second capacitor are non-radix 2 .
5. The apparatus according to claim 1 , wherein series-coupled inductor and first capacitor comprise an effective inductance.
6. The apparatus according to claim 5 , wherein the effective inductance and the second capacitor form an inductor-capacitor (LC) tank.
7. The apparatus according to claim 6 , wherein the LC tank and the first and second inverters form an oscillator having an oscillation frequency.
8. The apparatus according to claim 1 , wherein the DCO has an oscillation frequency that depends on a capacitance value of the first capacitor.
9. The apparatus according to claim 8 , wherein the oscillation frequency further depends on a capacitance value of the second capacitor.
10. An apparatus, comprising:
a digitally controlled oscillator (DCO) comprising:
a first capacitor having first and second terminals;
a first inductor having first and second terminals, wherein the first terminal is dotted and is coupled to the first terminal of the first capacitor;
a second inductor having first and second terminals, wherein the first terminal is dotted and is coupled to the second terminal of the first capacitor; and
a set of capacitors coupled in a H-configuration, wherein a first terminal of the H-configuration is coupled to the second terminal of the first inductor, and the second terminal of the H-configuration is coupled to the second terminal of the second inductor.
11. The apparatus according to claim 10 , wherein the DCO further comprises:
a first inverter coupled in parallel with the first capacitor; and
a second inverter coupled back-to-back to the first inverter.
12. The apparatus according to claim 11 , wherein the DCO further comprises a digital-to-analog converter (DAC) to vary a capacitance of the first capacitor in response to a first set of bits.
13. The apparatus according to claim 12 , wherein the DAC further varies a capacitance of the set of capacitors in response to a second set of bits.
14. The apparatus according to claim 10 , wherein the set of capacitors comprises a set of three capacitors.
15. An apparatus, comprising:
a digitally controlled oscillator (DCO) comprising:
a first capacitor having first and second terminals;
a first inductor having first and second terminals, wherein the first terminal is dotted and is coupled to the first terminal of the first capacitor;
a second inductor having first and second terminals, wherein the first terminal is dotted, and wherein the second terminal is coupled to the second terminal of the first capacitor; and
a set of capacitors coupled in a H-configuration, wherein a first terminal of the H-configuration is coupled to the second terminal of the first inductor, and the second terminal of the H-configuration is coupled to the first terminal of the second inductor.
16. The apparatus according to claim 15 , wherein the DCO further comprises:
a first inverter coupled in parallel with the first capacitor; and
a second inverter coupled back-to-back to the first inverter.
17. The apparatus according to claim 16 , wherein the DCO further comprises a digital-to-analog converter (DAC) to vary a capacitance of the first capacitor in response to a first set of bits.
18. The apparatus according to claim 17 , wherein the DAC further varies a capacitance of the set of capacitors in response to a second set of bits.
19. The apparatus according to claim 15 , wherein the set of capacitors comprises a set of three capacitors.
20. The apparatus according to claim 1 , wherein the DAC varies a capacitance of the second capacitor in response to a second set of bits.