Methods and apparatus of charge-sharing locking with digital controlled oscillators

An integrated circuit (IC) device comprising:

• a ring based digitally controlled oscillator (DCO) having a first inverter and a second inverter;
• a first charge-sharing switch;
• a first charge-sharing capacitor having a first terminal coupled to an input terminal of the first inverter through the first charge-sharing switch;
• a first pre-charge switch having a first terminal connected to the first terminal of the first charge-sharing capacitor and having a second terminal configured to receive a first target voltage, wherein the first pre-charge switch and the first charge-sharing switch are serially connected between the second terminal of the first pre-charge switch and the input terminal of the first inverter;
• a second charge-sharing capacitor having a first terminal coupled to an output terminal the first inverter;
• a second charge-sharing switch connected between the first terminal of the second charge-sharing capacitor and the output terminal the first inverter, and wherein the second charge-sharing switch is configured to set a voltage at the output terminal of the first inverter to a value that is equal to a voltage at the first terminal of the second charge-sharing capacitor in response to a condition that the second charge-sharing switch is driven into a connected state;
• and
• a second pre-charge switch having a first terminal connected to the first terminal of the second charge-sharing capacitor and having a second terminal configured to receive a second target voltage, wherein the second pre-charge switch and the second charge-sharing switch are serially connected between the second terminal of the second pre-charge switch and the input terminal of the second inverter.

An integrated circuit (IC) device comprising:

• a ring based digitally controlled oscillator (DCO) having a first inverter and a second inverter;
• a first charge-sharing switch;
• a first charge-sharing capacitor having a first terminal coupled to a first input terminal of the first inverter through the first charge-sharing switch;
• a first pre-charge switch having a first terminal connected to the first terminal of the first charge-sharing capacitor and having a second terminal configured to receive a first target voltage, wherein the first pre-charge switch and the first charge-sharing switch are serially connected between the second terminal of the first pre-charge switch and the first input terminal of the first inverter;
• a second charge-sharing switch;
• a second charge-sharing capacitor having a first terminal coupled an output terminal of the second inverter through the second charge-sharing switch, wherein the second charge-sharing switch is configured to set a voltage at the output terminal of the second inverter to a value that is equal to a voltage at the first terminal of the second charge-sharing capacitor in response to a condition that the second charge-sharing switch is driven into a connected state;
• and
• a second pre-charge switch having a first terminal connected to the first terminal of the second charge-sharing capacitor and having a second terminal configured to receive a second target voltage, wherein the second pre-charge switch and the second charge-sharing switch are serially connected between the second terminal of the second pre-charge switch and the output terminal of the second inverter.