Low-noise low-emission crystal oscillator and method thereof
AssigneeRealtek Semiconductor Corp.
InventorChia-Liang (Leon) Lin
Life of this patent
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Abstract
A crystal oscillator includes an inverter configured to receive a first voltage at a first node and output a second voltage at a second node, a stacked-diode feedback network inserted between the first node and the second node, a waveform shaper configured to couple the second node to a third node in accordance with the first voltage, a crystal inserted between a fourth node and a fifth node, wherein the fourth node is coupled to the third node, and the fifth node is coupled to the first node, a first shunt capacitor inserted between the fourth node and a ground node, and a second shunt capacitor inserted between the fifth node to and the ground node.
Claims12
A crystal oscillator comprising:
- an inverter configured to receive a first voltage at a first node and output a second voltage at a second node;
- a feedback network inserted between the first node and the second node, the feedback network comprising a parallel connection of a first branch and a second branch, the first branch comprising a first diode and a second diode stacked up in a forward direction, the second branch comprising a third diode and a fourth diode stacked up in a reverse direction;
- a waveform shaper configured to couple the second node to a third node in accordance with the first voltage, the waveform shaper comprising a parallel connection of a coupling resistor, an NMOS (n-channel metal oxide semiconductor) transistor, and a PMOS (p-channel metal oxide semiconductor) transistor;
- a crystal inserted between a fourth node and a fifth node, wherein the fourth node is coupled to the third node, and the fifth node is coupled to the first node;
- a first shunt capacitor inserted between the fourth node and a ground node;
- and
- a second shunt capacitor inserted between the fifth node to and the ground node.
A method comprising:
- incorporating an inverter to amplify a first voltage at a first node into a second voltage at a second node;
- inserting a waveform shaper between the second node and a third node, wherein the waveform shaper comprises a parallel connection of a resistor, an NMOS (n-channel metal oxide semiconductor) transistor, and a PMOS (p-channel metal oxide semiconductor) transistor;
- inserting a crystal between a fourth node and a fifth node, wherein the fourth node is coupled to the third node, and the fifth node is coupled to the first node;
- inserting a first shunt capacitor between the fourth node and a ground node;
- inserting a second shunt capacitor between the fifth node and the ground node;
- and
- inserting a feedback network between the second node and the first node, wherein the feedback network comprises a parallel connection of a first branch and a second branch, the first branch comprising a first diode and a second diode stacked in a forward direction, the second branch comprising a third diode and fourth diode stacked in a reverse direction.
Dependencies are inferred from the claim text.