Oscillator circuit with RF suppression
First Claim
1. An arrangement for use in an electricity meter comprising:
- a metrology circuit operably coupled to detect and measure electrical signals provided to a load, the metrology circuit including a processing unit configured to generate metering information based on the measured electrical signals, the processing unit using clocking signals to maintain a real-time clock and to generate clock signals for metrology circuit operations;
a phase-locked loop circuit configured to provide the clocking signals to the metrology circuit processing unit, the phase-locked loop circuit having a reference frequency input;
an oscillator circuit including a crystal resonator coupled between a first node and a second node, and a further element coupled between the first node and the second node, a first capacitor coupled between the first node and ground, and a first impedance element in a first circuit path from the first node to ground through the first capacitor; and
wherein each circuit path through the first node, the first capacitor and the second node passes through the first impedance element,wherein the first impedance element is configured to attenuate RF signals that are radiated onto at least portions of the oscillator circuit; and
wherein the second node is electrically directly coupled to the reference frequency input of the phase-locked loop.
2 Assignments
0 Petitions
Accused Products
Abstract
An oscillator circuit includes a phase-locked loop, a crystal resonator, first and second capacitors, and first and second impedance elements. The phase-locked loop is coupled between a first node and a second node. The crystal resonator is also coupled between the first node and the second node. The first capacitor is coupled between the first node and ground, and the second capacitor is coupled between the second node and ground. The first impedance element is coupled in a first circuit path from the first node to ground through the first capacitor. The second impedance element is coupled in a second circuit path from the second node to ground through the second capacitor.
37 Citations
14 Claims
-
1. An arrangement for use in an electricity meter comprising:
-
a metrology circuit operably coupled to detect and measure electrical signals provided to a load, the metrology circuit including a processing unit configured to generate metering information based on the measured electrical signals, the processing unit using clocking signals to maintain a real-time clock and to generate clock signals for metrology circuit operations; a phase-locked loop circuit configured to provide the clocking signals to the metrology circuit processing unit, the phase-locked loop circuit having a reference frequency input; an oscillator circuit including a crystal resonator coupled between a first node and a second node, and a further element coupled between the first node and the second node, a first capacitor coupled between the first node and ground, and a first impedance element in a first circuit path from the first node to ground through the first capacitor; and wherein each circuit path through the first node, the first capacitor and the second node passes through the first impedance element, wherein the first impedance element is configured to attenuate RF signals that are radiated onto at least portions of the oscillator circuit; and wherein the second node is electrically directly coupled to the reference frequency input of the phase-locked loop. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
-
Specification