Oscillator Circuit with RF Suppression

• US 20110193569A1
• Filed: 02/11/2011
• Published: 08/11/2011
• Est. Priority Date: 02/11/2010
• Status: Active Grant

• Current Assignee: Landis+Gyr AG (Landis+Gyr Group AG)
• Original Assignee: Landis+Gyr Inc. (Landis+Gyr Group AG)
• Inventors: AlRawi, Saieb
• Granted Patent: US 9,869,698 B2
• Time in Patent Office: Days
• US Class Current: 324/652
• CPC Class Codes: G01R 11/16 Adaptations of counters to electricity meters
• CPC Class Codes: G01R 22/061 Details of electronic electricity meters
• CPC Class Codes: G01R 27/28 Measuring attenuation, gain, phase shift or derived characteristics of electric four pole networks, i.e. two-port networks; Measuring transient response in line transmission systems H04B3/46
• CPC Class Codes: H03B 2200/0012 Pierce oscillator
• CPC Class Codes: H03B 5/30 with frequency-determining element being electromechanical resonator
• CPC Class Codes: H03B 5/36 active element in amplifier being semiconductor device H03B5/323, H03B5/326 , H03B5/38 take precedence

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.

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;

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 includes the first impedance element, and

wherein the first impedance element is configured to attenuate RF signals that are radiated onto at least portions of the oscillator circuit.

2. The arrangement of claim 1, wherein the first impedance element comprises a ferrite bead.

3. The arrangement of claim 1, wherein the further element comprises an amplifier.

4. The arrangement of claim 1, wherein the oscillator circuit further includes a second impedance element in a second circuit path from the second node to ground through a second capacitor.

5. The arrangement of claim 4, wherein the first impedance element and the second impedance element are substantially identical.

6. The arrangement of claim 4, wherein the first impedance element and the second impedance element comprise ferrite beads.

7. The arrangement of claim 1, further comprising an RF communication transmission device configured to transmit metering information to a remote location, the radiated RF signals originating from the RF communication transmission device.

8. An oscillator circuit comprising:

an amplifier coupled between a first node and a second node;

a crystal resonator coupled between the first node and the second node;

a first capacitor coupled between the first node and ground;

a second capacitor coupled between the second node and ground;

a first impedance element in a first circuit path from the first node to ground through the first capacitor;

a second impedance element in a second circuit path from the second node to ground through the second capacitor.

9. The oscillator circuit of claim 8, wherein the first impedance element comprises a ferrite bead.

10. The oscillator circuit of claim 9, wherein the second impedance element comprises a ferrite bead.

11. The oscillator circuit of claim 8, wherein the first and second impedance elements comprise resistors.

12. The oscillator circuit of claim 8, wherein the first impedance is coupled between the crystal resonator and the first node.

13. The oscillator circuit of claim 8, wherein the first impedance element is coupled such that a direct path is defined between the crystal resonator and the first node.

14. The oscillator circuit of claim 8, further comprising a phase-locked loop having a reference frequency input, the reference frequency input connected to the second node.

15. The oscillator circuit of claim 14, wherein the first circuit path and the second path are non-overlapping upstream of ground.

16. An oscillator circuit comprising:

a crystal element coupled between a first node and a second node;

at least one oscillator circuit element operably coupled between the first node and the second node;

a first capacitor coupled between the first node and ground;

a second capacitor coupled between the second node and ground;

a ferrite bead in a first circuit path from the first node to ground through the first capacitor;

wherein each circuit path through the first node, the first capacitor and the second node includes the ferrite bead.

17. The oscillator circuit of claim 16, further comprising:

a second impedance element in a second circuit path from the second node to ground.

18. The oscillator circuit of claim 16, wherein the at least one oscillator circuit element includes an amplifier element.

19. The oscillator circuit of claim 16, wherein the ferrite bead is coupled between the crystal element and the first node.

20. The oscillator circuit of claim 16, wherein the ferrite bead is coupled such that a direct path is defined between the crystal element and the first node.