JPH04302016A - Reference signal generating circuit - Google Patents

Abstract

PURPOSE:To eliminate the rapid change of a phase at the time of switching a duplexed reference signal CONSTITUTION:One of output signals of two reference signal generators 11 and 12, is used as a reference, a phase difference between the two signals is detected, and the detected phase difference is adjusted by a delay circuit 14, so that the phase of the two reference signals can be made equal.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to means for controlling the phase of the oscillation output of a reference signal generating circuit. INDUSTRIAL APPLICATION This invention is utilized for a mobile communication radio|wireless apparatus.

0002

2. Description of the Related Art Conventionally, reference signal generation circuits that generate signals that are the basis of clocks used in devices have been duplicated, so that even if one of the reference signal generation circuits fails, the device will not become inoperable. It is composed of FIG. 2 shows an example of a conventional reference signal generation circuit. As shown in the figure, the conventional example has a first reference signal generator 21 and a second reference signal generator 22 as signal generation sources, and the outputs of the first and second reference signal generators 21 and 22 are used as signal generation sources. The output selection circuit 23 selects either the output of the first reference signal generator 21 or the output of the second reference signal generator 22 as a reference signal in response to a control signal 24. It was outputting.

0003

In such a conventional reference signal generation circuit, the output signal of the first reference signal generator 21 and the output signal of the second reference signal generator 22 are different in phase. The first reference signal generator 21 in the selection circuit 23
When switching between the output signal of the second reference signal generator 22 and the output signal of the second reference signal generator 22, the phase of the output signal of the output selection circuit 23 suddenly changes, causing various abnormalities in the circuit using this output signal for a short time. There was a drawback that there were cases where the synthesizer would be activated (for example, the synthesizer would be in an unlocked state for a short period of time).

SUMMARY OF THE INVENTION It is an object of the present invention to eliminate such drawbacks and to provide a reference signal generating circuit having means for preventing sudden changes in phase when switching outputs.

[0005]

[Means for Solving the Problems] The present invention includes a first reference signal generator, a second reference signal generator, and a first output signal of the first reference signal generator or the second output signal. and an output selection circuit that selects one of the signals related to the first output signal of the reference signal generator according to a control signal, wherein the second output signal of the first reference signal generator is a phase detection circuit for detecting a phase difference between the output signal and a second output signal of the second reference signal generator; and a phase detection circuit for detecting a phase difference between the output signal and a second output signal of the second reference signal generator; The present invention is characterized by comprising a delay circuit that changes the phase of the first output signal and supplies it to the output selection circuit as a signal related to the first output signal of the second reference signal generator.

[0006]

[Operation] The phase difference between the two signals is detected using the phase of one of the output signals of the two reference signal generators as a reference, and the detected phase difference is adjusted by the delay circuit. This makes the phases of the two reference signals equal and prevents sudden changes in phase during switching.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram of this embodiment. As shown in FIG. 1, this embodiment includes a reference signal generator 11,
a reference signal generator 12; and an output selection circuit 15 that selects either the first output signal of the reference signal generator 11 or a signal related to the first output signal of the reference signal generator 12 according to a control signal. Further, as means characteristic of the present invention, a phase detection circuit 13 for detecting a phase difference between the second output signal of the reference signal generator 11 and the second output signal of the reference signal generator 12; The phase of the first output signal of the reference signal generator 12 is changed according to the phase control signal from the phase detection circuit 13, and the signal is sent to the output selection circuit 15 as a signal related to the first output signal of the reference signal generator 12. and a delay circuit 14 that provides a delay circuit.

Next, the operation of this embodiment will be explained. Reference signal generator 11 and reference signal generator 12 generate reference signals having different phases. A first output signal of each reference signal generator 11, 12 is input to a phase detection circuit 13. A phase detection circuit 13 that receives the first output signals of the reference signal generators 11 and 12 uses the phase of the output signal of the reference signal generator 11 as a reference to detect the output signal of the reference signal generator 11 and the reference signal generator 12. Detects the phase difference with the output signal of the output signal, generates a control signal corresponding to the phase difference, and inputs the control signal to the delay circuit 14. The delay circuit 14 inputs the second output signal of the reference signal generator 12 and changes the phase of the input signal according to the control signal from the phase detection circuit 13.
control so that the phase is equal to the phase of the output signal. A delay circuit 14 having the same phase as the output signal of the reference signal generator 11
The output signal is input to the output selection circuit 15. The output selection circuit 15 receives the second output signal of the reference signal generator 11 and the output signal of the delay circuit 14, and selects one of them by a control signal and outputs the selected signal as a reference signal.

[0009]

[Effects of the Invention] The present invention uses a phase detection circuit to detect the phase difference between the outputs of two reference signal generators having different phases, and uses a delay circuit to adjust the phase of one reference signal generator to the same phase as the other reference signal. Therefore, even if the two input signals input to the output selection circuit are switched, the phase of the output signal does not change, and abnormal operation (for example, the synthesizer becomes unlocked) due to the sudden phase change of the reference signal that occurs at the time of switching. ) has the effect of preventing the occurrence of

[Brief explanation of drawings]

FIG. 1 is a block configuration diagram showing the configuration of an embodiment of the present invention.

FIG. 2 is a block configuration diagram showing the configuration of a conventional example.

[Explanation of symbols]

11. Reference signal generator 12 Reference signal generator 13 Phase detection circuit 14 Delay circuit 15 Output selection circuit 16 Control signal input terminal 17 Reference signal output terminal 21 Reference signal generator 22 Reference signal generator 23 Output selection circuit 24 Control signal input terminal 25 Reference signal output terminal

Claims (1)

[Claims] 1. A first reference signal generator, a second reference signal generator, and a first output signal of the first reference signal generator or a first output signal of the second reference signal generator. A reference signal generation circuit comprising an output selection circuit that selects one of the signals related to the output signal according to a control signal,
a phase detection circuit that detects a phase difference between a second output signal of the first reference signal generator and a second output signal of the second reference signal generator; and a phase control signal from the phase detection circuit. a delay circuit that changes the phase of the first output signal of the second reference signal generator in accordance with and supplies it to the output selection circuit as a signal related to the first output signal of the second reference signal generator; A reference signal generation circuit comprising: