Oscillator frequency accuracy and amplitude control
In examples, an electronic device comprises an oscillator circuit configured to provide an output signal and a controller coupled to the oscillator circuit. The controller is configured to receive first and second target rates; dynamically adjust a frequency accuracy of the output signal based on the first target rate; and dynamically adjust an amplitude of the output signal based on the second target rate.
1. An electronic device, comprising:
an oscillator circuit configured to provide an output signal; and
a controller coupled to the oscillator circuit and configured to:
receive first and second target rates;
dynamically adjust a frequency accuracy of the output signal based on the first target rate;
dynamically adjust an amplitude of the output signal based on the second target rate; and
interleave adjustments to the frequency accuracy and the amplitude to maintain energy in a crystal of the oscillator circuit within a target range.
2. The electronic device of claim 1 , wherein the oscillator circuit includes a variable capacitor, and wherein the controller is configured to dynamically adjust the frequency accuracy by adjusting the variable capacitor.
3. The electronic device of claim 1 , wherein the oscillator circuit includes a variable resistor, and wherein the controller is configured to dynamically adjust the amplitude by adjusting the variable resistor.
4. The electronic device of claim 1 , further comprising a second controller coupled to the oscillator circuit, the second controller configured to adjust a current mirror in the oscillator circuit to control the amplitude of the output signal.
5. The electronic device of claim 1 , wherein the oscillator circuit is a Pierce oscillator circuit.
6. The electronic device of claim 1 , wherein dynamically adjusting the frequency accuracy of the output signal comprises monotonically adjusting a capacitance of a variable capacitor of the oscillator circuit.
7. The electronic device of claim 1 , wherein dynamically adjusting the amplitude of the output signal comprises monotonically adjusting a current flowing through the oscillator circuit.
8. An electronic device, comprising:
an oscillator circuit including a first adjustable component configured to control a frequency accuracy of an output signal of the oscillator circuit and a second adjustable component configured to control an amplitude of the output signal; and
a controller coupled to the oscillator circuit and configured to:
adjust a first value of the first adjustable component to a first target value at a first rate that does not exceed a first threshold rate, wherein the first target value and first threshold rate are dynamically adjustable inputs to the controller; and
adjust a second value of the second adjustable component to a second target value at a second rate that does not exceed a second threshold rate, wherein the second target value and the second threshold rate are dynamically adjustable inputs to the controller.
9. The electronic device of claim 8 , wherein the oscillator circuit is a crystal oscillator circuit.
10. The electronic device of claim 8 , wherein the oscillator circuit is a Pierce oscillator circuit.
11. The electronic device of claim 8 , wherein the first adjustable component is a variable capacitor coupled to an amplifier of the oscillator circuit.
12. The electronic device of claim 8 , wherein the second adjustable component is a variable resistor configured to provide a variable resistance.
13. The electronic device of claim 8 , further comprising a second controller configured to control the amplitude of the output signal by adjusting a current mirror of the oscillator circuit, the current mirror coupled to an amplifier of the oscillator circuit.
14. The electronic device of claim 8 , wherein the first threshold rate includes a step size and a time increment, the step size indicating a maximum permissible change in the first value toward the first target value per instance of the time increment.
15. The electronic device of claim 8 , wherein the controller is configured to interleave adjustments to the first adjustable component with adjustments to the second adjustable component to maintain energy in a crystal of the oscillator circuit within a target range.
16. A method, comprising:
receiving a first target value and a first threshold rate for a frequency accuracy of an oscillator output signal;
receiving a second target value and a second threshold rate for an amplitude of the oscillator output signal;
adjusting a first value of the frequency accuracy of the oscillator output signal toward the first target value at a rate less than or equal to the first threshold rate; and
adjusting a second value of the amplitude of the oscillator output signal toward the second target value at a rate less than or equal to the second threshold rate.
17. The method of claim 16 , wherein the first threshold rate includes a step size and a time increment, the step size indicating a maximum permissible change in the first value toward the first target value per instance of the time increment.
18. The method of claim 16 , further comprising receiving a time increment and delaying the adjustment of the first value by the time increment.
19. The method of claim 16 , wherein adjusting the first value includes adjusting a variable capacitor coupled to an amplifier in an oscillator, the oscillator configured to output the oscillator output signal.
20. The method of claim 19 , wherein adjusting the second value includes adjusting a variable resistor configured to provide a variable resistance in the oscillator.
21. The method of claim 19 , further comprising interleaving adjustments to the first value with adjustments to the second value to maintain energy in a crystal of the oscillator within a target range.