Frequency monitoring circuitry with voltage conversion

Circuitry comprising:

• a voltage based frequency monitoring circuit configured to receive an input clock signal having an input clock frequency and to generate a corresponding output voltage having a first value when the input clock frequency is greater than a reference frequency and having a second value when the input clock frequency is less than the reference frequency;
• a coarse frequency monitoring circuit configured to receive the input clock signal and to output one or more count values;
• and
• an output circuit configured to generate a digital output based on the output voltage from the voltage based frequency monitoring circuit when the input clock frequency is within a first set of frequencies and based on the one or more count values from the coarse frequency monitoring circuit when the input clock frequency is within a second set of frequencies different than the first set of frequencies.

Frequency monitoring circuitry comprising:

• an analog-to-digital converter (ADC) having a first ADC input and a second ADC input;
• a first capacitor coupled to the first ADC input;
• a resistor selectively coupled to the second ADC input;
• a second capacitor coupled to the second ADC input;
• a first switch configured to pass a reference current to the first capacitor;
• a second switch configured to pass the reference current to the resistor;
• and
• a third switch configured to discharge the first capacitor.