REFERENCE OSCILLATOR AND ITS USE

• US 20080303601A1
• Filed: 05/30/2008
• Published: 12/11/2008
• Est. Priority Date: 06/01/2007
• Status: Active Grant

• Current Assignee: Hitachi, Ltd., Qualcomm, Inc.
• Original Assignee: Nemerix, SA
• Inventors: YOUNG, Phil
• Granted Patent: US 7,936,227 B2
• Time in Patent Office: Days
• US Class Current: 331/66
• CPC Class Codes: G01S 19/34 Power consumption
• CPC Class Codes: G01S 19/35 Constructional details or hardware or software details of the signal processing chain
• CPC Class Codes: H03L 1/028 of generators comprising piezoelectric resonators H03L1/021, H03L1/022 take precedence; oscillation generators with a piezoelectric resonator H03B5/32

Abstract

A reference clock circuit (170), has a low-power mode, in which the frequency consumption is reduced, and including an internal counter, accumulating time spent in low-power mode. The circuit includes a crystal resonator (60), an oscillator circuit (70), and a temperature compensation circuit (80), providing a stable clock output (85). During low-power mode temperature compensation can be switched off. The circuit further provides a wakeup signal (107) after a preset time in low-power mode.

Claims

1. A reference oscillator circuit, including:

a crystal resonator, having a resonance frequency;

an oscillator arranged to maintain the resonator in oscillation at the resonance frequency, and generate an oscillating signal at the resonance frequency,

a temperature compensation circuit, providing a temperature-compensated clock output signal,

wherein the reference circuit has at least one normal operational state and a low-power state, wherein the power consumption of the reference circuit in the low-power state is lower than the power consumption of the reference circuit in the normal state, and a command input, arranged to change the state of the reference circuit according to the value present at the command input,

characterized by;

a counter, externally accessible by a counter output interface, arranged to count a signal derived from said oscillator, while the reference circuit is in low-power state.

2. The reference oscillator according to claim 1, further comprising a logic element stopping the counter when the reference circuit exits low-power state.

3. The reference oscillator according to claim 1, operatively arranged to reset the counter when the reference circuit enters low-power state.

4. The reference oscillator of according to claim 1, further including a wakeup output arranged to generate a wakeup signal after a predefined value has been reached by said counter.

5. The reference oscillator according to claim 1, wherein the temperature compensation circuit is disabled in the low-power state.

6. Use of a reference oscillator according to claim 1 in a GNSS receiver, wherein the receiver has a idle mode, in which satellite tracking is not carried out and the reference circuit is put into low-power mode, the receiver being arranged to save a value of the time at which the receiver enters into idle mode, to retrieve the time elapsed in idle mode from the counter of the reference circuit, and to resume acquisition and tracking of satellites based on such knowledge of the time elapsed in idle state.

7. The reference oscillator according to claim 2, operatively arranged to reset the counter when the reference circuit enters low-power state.

8. The reference oscillator of according to claim 2, further including a wakeup output arranged to generate a wakeup signal after a predefined value has been reached by said counter.

9. The reference oscillator of according to claim 3, further including a wakeup output arranged to generate a wakeup signal after a predefined value has been reached by said counter.

10. The reference oscillator according to claim 2, wherein the temperature compensation circuit is disabled in the low-power state.

11. The reference oscillator according to claim 3, wherein the temperature compensation circuit is disabled in the low-power state.

12. The reference oscillator according to claim 4, wherein the temperature compensation circuit is disabled in the low-power state.

13. Use of a reference oscillator according to claim 2 in a GNSS receiver, wherein the receiver has a idle mode, in which satellite tracking is not carried out and the reference circuit is put into low-power mode, the receiver being arranged to save a value of the time at which the receiver enters into idle mode, to retrieve the time elapsed in idle mode from the counter of the reference circuit, and to resume acquisition and tracking of satellites based on such knowledge of the time elapsed in idle state.

14. Use of a reference oscillator according to claim 3 in a GNSS receiver, wherein the receiver has a idle mode, in which satellite tracking is not carried out and the reference circuit is put into low-power mode, the receiver being arranged to save a value of the time at which the receiver enters into idle mode, to retrieve the time elapsed in idle mode from the counter of the reference circuit, and to resume acquisition and tracking of satellites based on such knowledge of the time elapsed in idle state.

15. Use of a reference oscillator according to claim 4 in a GNSS receiver, wherein the receiver has a idle mode, in which satellite tracking is not carried out and the reference circuit is put into low-power mode, the receiver being arranged to save a value of the time at which the receiver enters into idle mode, to retrieve the time elapsed in idle mode from the counter of the reference circuit, and to resume acquisition and tracking of satellites based on such knowledge of the time elapsed in idle state.

16. Use of a reference oscillator according to claim 5 in a GNSS receiver, wherein the receiver has a idle mode, in which satellite tracking is not carried out and the reference circuit is put into low-power mode, the receiver being arranged to save a value of the time at which the receiver enters into idle mode, to retrieve the time elapsed in idle mode from the counter of the reference circuit, and to resume acquisition and tracking of satellites based on such knowledge of the time elapsed in idle state.