JPS5866422A - Phase locked loop circuit - Google Patents

Abstract

PURPOSE:To decrease the power consumption of a phase lock loop circuit, by providing a switch which closes for a prescribed period when a change of the working conditions is detected for the main body of the loop circuit and then conducting an intermittent operation of the circuit main body. CONSTITUTION:A switch 7 which opens and closes the loop of the main body 6 of a PLL circuit by the control of a control circuit 8 is provided between a phase comparator 4 and a loop filter 5. A switch 11 is set between a frequency divider 3 and the comparator 4. When the switches 7 and 11 are closed, a voltage control oscillator 2 has oscillations with a locked frequency. Thus a switch 13 is changed over toward the filter 5, and the control voltage of the oscillator 2 is stored in a control circuit 8. The switches 7, 11 and 13 are opened after a prescribed period of time, and the loop of the main body 6 is set in a non-lock working state. However the oscillator 2 has its continuous operation. These switches are closed again when the value of a temperature detector 12 is changed from the stored value. Thus the oscillating frequency of the oscillator 2 is corrected.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a phase-locked loop circuit that reduces power consumption.

In recent years, frequency synthesizers using phase-locked loop circuits (PLL circuits) have been widely used in wireless communication devices and the like in order to share radio frequencies among a large number of terminals and improve the utilization rate of radio waves. jJxa is a block diagram showing the basic configuration of a frequency synthesizer using a conventional phase-locked loop circuit. This number of plates is determined by detecting the phase difference between the output of the reference oscillator J and the output obtained by dividing the output of the voltage controlled oscillator 2 by the divider 3 using the phase comparator 4, and passing this detected output through the loop filter 5. The signal is then supplied to the voltage controlled oscillator 2 to obtain a desired oscillation frequency.

However, in devices using conventional phase-locked loop circuits, the power consumption of the phase-locked loop circuit itself is large because the phase-locked loop circuit is always in an operating state. It was difficult to apply it to power-consuming devices and devices.

The present invention has been made in view of the above-mentioned circumstances, and its purpose is to reduce power consumption by operating the phase group circuit body intermittently, and to efficiently perform the above-mentioned intermittent operation. An object of the present invention is to provide a phase-locked loop circuit.

Hereinafter, one embodiment of the present invention will be described with reference to FIG. Note that the same parts as in FIG. 1 are given the same reference numerals and detailed explanations will be omitted. In the WIz diagram, a first switch 7 is interposed between the phase comparator 4 and the loop filter 5 of the Puezlo loop circuit main body 6. The first swing f1 loops open and close the phase group circuit main body 6 according to instructions from a control circuit 8, which will be described later, and is connected to the digital converter 5 when the loop is opened. Further, a second switch 11 is provided in the power output supply path between the power supply 10 and the branching unit 3 and phase comparator 4 of the phase-locked loop circuit main body 6. This second switch 11 turns off and on the power output supply path to the frequency divider 3 and phase comparator 4 according to instructions from the control circuit 8.

By the way, the phase-locked loop circuit of this embodiment has a temperature detector 12 that detects the ambient temperature, which is one element of the operating conditions of this circuit.

Then, the detection output of the temperature detector 12 is transmitted together with the output of the loop filter 5, that is, the control voltage of the voltage controlled oscillator 2, through the switch 13'j & of the I83 and the analog-to-digital (A/D) converter 14. Control circuit 8
It has been introduced to Here, the third switch is - control circuit 8
The control circuit 8 is for selectively guiding the detection output of the temperature detector 12 and the control voltage of the voltage-controlled oscillator 2 to the control circuit 8 in accordance with instructions from the control circuit 8. It performs a series of control operations such as storing and determining the results of detection by the temperature detector 12.

Next, the operation of the circuit configured as above will be explained. First, when a switch close signal is output from the control circuit 8 to each switch 7° 1181B, the output of 1o is supplied, and the phase lock loop circuit 6 starts locking operation. As a result, the voltage controlled oscillator 2 oscillates at a frequency determined by the output frequency of the reference oscillator l and the frequency division number of the frequency divider 3,
It is locked to this oscillation frequency. On the other hand, the 303rd switch f1B is switched to the loop filter 5 side by the switch closing signal from the control circuit 8, and as a result, the control ``magnetic pressure'' of the voltage controlled oscillator 2 in the locked state is converted into a digital signal by the A/D converter 14. The stored control voltage is stored in the control circuit 8. The stored control voltage is also read out to the D/A converter 9.

Then, when the time required for the above-mentioned locking operation has elapsed and a switch opening signal is output from the control circuit 8 to each switch 7m11g13, the power supply to the branching unit 3 and the phase comparator 4 is cut off, and the first The switch 7 switches from the phase comparator 4 side to the D/A converter 9 side, and the loop of the phase-locked loop circuit main body 6 is in a non-locking operating state.

Become. However, at this time, the control circuit 8 outputs one after another,
Since the control voltage converted by the D/A converter 9 is supplied to the voltage controlled oscillator 2 via the loop filter 5, the oscillation operation of the voltage controlled oscillator 2 continues. On the other hand, when the third switch 13 is switched from the loop filter 5 side to the temperature detector 12 side by the switch opening signal from the control circuit 8, the detected value of the temperature detector 12 immediately after this switching is A.
The signal is introduced into the control circuit 8 via the /De converter 14 and stored. Then, the detected values obtained by the temperature detector 12 are sequentially introduced into the control circuit 8.

Now, in this state, if the detected value obtained by the temperature detector 12 changes by a predetermined amount or more from the value stored immediately after the locking operation due to, for example, a rise in the room temperature, the control circuit 8 detects this. A switch open signal is output to each switch 1alleJB. As a result, the loop of the phase-locked loop circuit main body 6 is closed, and the output of the power supply 10 is supplied to the frequency divider 38 and the phase comparator 4, so that the phase-locked loop circuit main body 6 performs a locking operation. As a result, the oscillation frequency of the voltage controlled oscillator 2 is corrected for temperature fluctuations. Also, the voltage controlled oscillator 2 after this modification
The control voltage is stored in the control circuit 8 in place of the value before correction and is used for the oscillation action of the voltage controlled oscillator 2 when the primary loop is opened.

When the lock operation is completed, a switch open signal is output from the control circuit 8 to each switch 7m11m1:I, and the loop becomes open, and during this time the temperature is monitored as described above.

Here, since the time required for the above-mentioned locking operation is about 1 slow and the time for changing the predetermined amount is long, the power consumption reduced by the above-mentioned intermittent locking operation becomes very large.

In this way, according to the circuit of the present embodiment, the phase-locked loop circuit main body 6 can be locked intermittently, so that the power consumption of the circuit can be significantly reduced.

Therefore, it is possible to apply the present invention to, for example, a portable radio device using a battery, and it is possible to downsize the portable radio device and improve its performance. In addition, in this embodiment, the ambient temperature, which is an important element of the circuit operating conditions, is monitored, and when the ambient temperature shows a change exceeding the allowable amount, a lock operation is performed. The intermittent locking operation can be performed more efficiently and reliably than a method in which the cycle of the locking operation is fixed using a timer or the like. Furthermore, in this embodiment, since the control voltage of the voltage controlled oscillator 2 is converted into a digital signal and stored in the memory, there is no fluctuation in the stored control voltage value. Therefore, intermittent locking operation can be performed with higher precision than when a capacitor is used as the storage means.

Note that the present invention is not limited to the above embodiments.
For example, in addition to changes in ambient temperature as operating conditions,
Fluctuations in the O voltage may be monitored and a locking operation may be performed in accordance with the monitoring results.Also, the control based on the ambient temperature and the control based on the power supply voltage may be performed in parallel.

Further, in the above embodiment, the power supply to the branching unit 3 and the phase comparator 4 is cut off, but it is also possible to cut off the power supply to an external circuit such as a reference oscillator, and the loop filter 6 may also be cut off. In the case where the loop filter 6 is constituted by an active filter, the power supply to the loop filter 6 may be cut off.In short, at least one of the circuits constituting the loop except for the voltage controlled oscillator All you need to do is cut off the power supply to one circuit. In addition, the transition from lock operation to non-operation state may be performed by detecting a lock completion signal generated from a phase comparator.If the phase comparator does not have a lock completion signal generation function, a timer is used to set the lock completion signal in advance. may also be set.

In addition, the configuration of each switch ra11.1B, the application of the phase lock group circuit, the control procedure for intermittent locking operation, etc. can be modified in various ways without departing from the gist of the present invention.

As described in detail above, the first and second switches are provided to turn on and off the power supply to the loop g of the phase-locked loop circuit and the circuit, respectively, and a memory circuit is provided to store the control voltage of the voltage controlled oscillator. and monitoring the operating conditions of the circuit, and depending on the monitoring results, the first
According to the present invention, in which the S and second switches are closed, the main body of the phase-locked loop circuit is operated intermittently to reduce power consumption, and the intermittent operation can be efficiently performed. EZROTS group circuits can be provided.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the basic configuration of a frequency synthesizer using a conventional phase group circuit, and FIG. 2 is a circuit block diagram of a frequency synthesizer using a phase group circuit according to an embodiment of the present invention. be. l... Reference oscillator, 2... Voltage controlled oscillator (vc"
o) 3... Frequency divider, 4... Phase comparator, 5-... Loop filter, 6... Phase group circuit body,
7... First switch, 8... Control circuit, 9...
D/A converter, 10 - power supply, 71 - second switch, 12 - temperature detector, 13 - third switch, 14
...A/D converter. Applicant's representative Patent attorney Takehiko Suzue Continued from page 1 ■Inventor Toru Kushita 3-1-1 Asahigaoka, Hino City Hino Factory, Tokyo Shibaura Electric Co., Ltd.

Claims (1)

[Claims] F: c-socket A power source for at least one circuit out of the loop circuit body, the first switch that opens and closes the loop of this phase-locked loop circuit body, and each circuit other than the voltage-controlled oscillator of the phase-locked loop circuit body. a second switch for turning off and on the phase-locked loop circuit, and a second switch for storing the control voltage of the voltage-controlled oscillator when the loop of the phase-locked loop circuit main body is opened, and transmitting the stored control voltage to the voltage-controlled oscillator when the loop of the phase-locked loop circuit main body is opened. A memory circuit that supplies power to continue the oscillation operation, a monitoring circuit that monitors the operating conditions of the phase-locked loop circuit body and detects fluctuations when the loop of the phase-locked loop circuit body is opened, and this monitoring circuit and a lock control circuit that turns each of the first and second switches from an open state to a closed state for a predetermined period of time to perform a locking operation on the phase lock loop circuit body when a change in the operating condition is detected. Features a phase-locked loop circuit.