Frequency spread spectrum (FSS) oscillator

An oscillator, comprising:

• a reference voltage generator circuit configurable to provide a first reference voltage across a first capacitor, the reference voltage generator circuit comprising:
• a first comparator configurable to perform a comparison to compare the first reference voltage to second and third reference voltages and to provide a first comparator output signal based on the comparison;
• and
• first, second, and third switches coupled to the first comparator, the first and second switches configurable to increase the first reference voltage based on the comparison, and the first and third switches configurable to decrease the first reference voltage based on the comparison, the first switch operable by a clock signal;
• and
• an oscillation circuit coupled to the reference voltage generator circuit and comprising:
• a second comparator coupled to a second capacitor, the second comparator configurable to compare a voltage across the second capacitor to the first reference voltage to provide a second comparator output signal;
• a third capacitor configurable to be charged based on the second comparator output signal;
• an inverter configurable to provide the clock signal by inverting a voltage across the third capacitor;
• and
• a fourth switch configurable to control a voltage across the second capacitor based on the clock signal.

An oscillator, comprising:

• a first comparator including a first comparator output and first and second comparator inputs, the first comparator input switchably coupled to multiple reference voltage terminals;
• a first switch coupled to the second comparator input;
• second and third switches coupled to each other and to the first switch, the second switch coupled to a power supply and the third switch coupled to a ground terminal;
• a first capacitor coupled between the first switch and the second comparator input;
• a first inverter having a first inverter output and a first inverter input, the first inverter input coupled to the first comparator output, the first inverter output coupled to the second switch;
• a second comparator including a second comparator output and third and fourth comparator inputs, the third comparator input coupled to the power supply, the fourth comparator input coupled to the second comparator input;
• a second capacitor coupled between the third comparator input and the ground terminal;
• a fourth switch coupled in parallel to the second capacitor;
• a fifth switch coupled to the second comparator output;
• a third capacitor coupled in parallel to the fifth switch, the third capacitor and the fifth switch coupled to the power supply;
• and
• a second inverter having a second inverter output and a second inverter input, the second inverter output coupled to the fourth switch and the second inverter input coupled to the fifth switch and the third capacitor.