Low-noise crystal oscillator using self-timed intermittent DC coupling for biasing

A crystal oscillator comprising:

• a PMOS (p-channel semiconductor) transistor having its gate, source, and drain terminals connected to a first gate node, a source node, and a ground node, respectively;
• an NMOS (n-channel metal-oxide semiconductor) transistor having its gate, source, and drain terminals connected to a second gate node, the source node, and a power supply node, respectively;
• a feedback capacitor positioned between the source node and one of the first gate node and the second gate node;
• a shunt capacitor positioned between the source node and one of the power supply node and the ground node;
• an AC (alternating current) coupling capacitor positioned between the first gate node and the second gate node;
• a crystal positioned between one of the first gate node and the second gate node and one of the ground node and the power supply node;
• a first DC (direct current) coupling network configured to couple a first bias node to the first gate node in accordance with a state of a first gate voltage at the first gate node;
• and
• a second DC coupling network configured to couple a second bias node to the second gate node in accordance with a state of a second gate voltage at the second gate node,
• wherein:
• both the first bias node and the second bias node are configured with an impedance that results in stable, and steady DC bias voltages;
• the first DC coupling network is substantially non-conductive when the first gate voltage is below a certain voltage level;
• and
• the first DC coupling network comprises a diode-connected MOS (metal-oxide semiconductor) transistor and a resistor and the certain voltage level is determined by a threshold voltage of the diode-connected MOS transistor;
• wherein the second DC coupling network is substantially non-conductive when the second gate voltage is above a certain voltage level;
• wherein the second DC coupling network comprises a diode-connected MOS (metal-oxide semiconductor) transistor and a resistor and the certain voltage level is determined by a threshold voltage of the diode-connected MOS transistor.