JPH0362731A - Intermittent operation pll circuit - Google Patents

Abstract

PURPOSE:To realize a PLL circuit with a stable intermittent operation by providing a feedback function detecting a phase difference of a phase comparator to apply intermittent operation to the PLL circuit. CONSTITUTION:A phase difference detection circuit 12 detects a phase difference of a phase comparator 7 and gives an instruction to turn off a switch circuit 2 to a switch control circuit 3 when the phase difference is within a prescribed permissible range. Conversely when the phase difference exceeds the prescribed permissible range, the phase difference detection circuit 12 gives an instruction to turn on the switch circuit 2 to the switch control circuit 3. Thus, the PLL circuit with an intermittent operation provided with a feedback function using a phase difference is obtained, in which a power voltage terminal 1 is opened when the frequency from a VCO 9 is made stable and the power voltage terminal 1 is closed when the frequency from the VCO 9 has a phase difference from a reference signal.

Description

[Detailed Description of the Invention] [Industrial Field of Application] This invention relates to an intermittent operation PLL (Phase Looked Loop) used to reduce power consumption.
)Ill path〇 [Prior art] Fig. 2 is a block diagram of a conventional PL and L circuit that performs intermittent operation. In the figure, 1 and 11 are power supply voltage supply terminals for operating the PLL circuit, and 1 is a reference signal oscillator 4.1 of the PLL circuit. Fixed frequency divider5. Variable frequency divider 61 Terminal for supplying power supply voltage to phase comparator 1, 11 is loop filter 8
and V OO (Voltag@0ontrO1led
This is a terminal that supplies the power supply voltage to the oscillator (voltage controlled oscillator). 2 is a switch circuit for intermittent operation, 3 is a switch control circuit that controls ON/OFF of the switch, 4 is a reference signal oscillator, and 5 is a fixed frequency divider for dividing the reference signal of reference signal oscillator B. vessel, 6 is 9
07, which is a variable frequency divider for dividing the oscillation frequency generated by the oscillation frequency, is used to compare the phase of the signal divided by the fixed frequency divider 5 and the signal divided by the variable frequency divider 6. The phase comparator 08 is a loop filter for converting the phase difference output from 7 into a voltage. The capacitor O is used to hold the voltage of the loop filter 8 while the control switch 2 is OFF.

Next, the operation will be explained. This PLL circuit has 9 VO
The purpose is to stabilize the output frequency of O. 4
A fixed frequency divider 5 divides the signal generated by the reference signal oscillator 5, and this frequency-divided signal is used as a reference, and the reference signal and the output signal of the variable frequency divider 6 are configured to be in the same phase. ing. If there is a phase difference between the output signal of 5 and the output signal of 6, that phase difference is output to the phase comparator of 7, the phase difference is converted into a voltage by the loop filter and filter of 8, and the converted voltage is converted into a voltage of 9. is applied to WOO. Due to this voltage variation, the output frequency of 9 changes and is input to the variable frequency divider 6, and this input signal is frequency-divided by the variable frequency divider 6 and input to the phase comparator 7. Thereafter, this operation is repeated until the output signals of the fixed frequency divider 5 and the phase comparator P have the same phase.

This conventional PLL circuit not only operates as described above, but also includes a circuit that performs intermittent operation in order to reduce power consumption. This intermittent operation is intended to reduce power consumption by reducing the power supply voltage supplied to the PLL circuit to 0IFF for a certain period of time.
The control is performed by the switch control circuit 3. The PLL operation described above is performed only when the switch circuit 82 is ON, and the PLL does not operate when the switch circuit 82 is in the ON state.

[Problem to be solved by the invention]

Since the conventional PLL circuit was configured as above,
Control the switch control circuit to 0IFF for a certain period of time,
It is necessary to perform 0N10FF operation on Quinaminku, such as keeping it in the FF state for a certain period of time, and for this reason, when the switch circuit is 0IFF, the PLJ and circuit do not operate and VOO becomes extremely unstable. There was a problem.

This invention was made to solve the above-mentioned problems, and its object is to control a switch control @ circuit by detecting the output signal of a phase comparator.

[Means to solve the problem]

In the intermittent operation PLL circuit according to the present invention, if the phase difference between the output signal of the fixed frequency divider and the output signal of the variable frequency divider is within a certain tolerance range, the switch control circuit turns on the ON signal. [Function] The intermittent operation PLL circuit according to the present invention changes the power supply voltage to the oIPIF and the WO
A PLL operation is performed with a feedback function such as turning on the power supply voltage when a shift in the frequency of O occurs.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows a block diagram of an intermittent operation pLb circuit according to an embodiment of the present invention, and in the figure, the same reference numerals as in the conventional circuit denote the same parts. In the figure, 12 is a phase difference detection circuit that detects the phase difference of the phase comparator 7, and if the phase difference is within a certain tolerance range, the switch control circuit 3 is configured so that the switch circuit 2 becomes 0IFF. It outputs a signal to send a command, and conversely, if the phase difference of the phase comparator 7 is above a certain tolerance range, it sends a command to the switch control circuit 3 to turn the switch circuit 2 ON and Z. Outputs a signal for As a result, when the frequency of VOO9 is stabilized, the power supply voltage terminal l is in the 0IPF state, and when the frequency of v009 has a phase difference with respect to the reference signal, the power supply voltage terminal l is in the 0IPF state.
An intermittent operation PLL circuit having a feedback function based on a phase difference such as N can be obtained.

〔Effect of the invention〕

As described above, according to the present invention, since a feedback function is provided to perform intermittent operation by detecting the phase difference of the phase comparator, more stable intermittent operation P
0 which can obtain LL circuit

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an intermittent operation PLL circuit according to an embodiment of the present invention, and FIG. 2 is a block diagram showing a conventional intermittent operation PLL circuit. In the figure, 1 is a power supply voltage terminal, 2 is a switch circuit, and 3 is a power supply voltage terminal.
4 is a switch control circuit, 4 is a reference signal generator, 5 is a fixed frequency divider, 6 is a movable frequency divider, 7 is a phase comparator, and 12 is a phase difference detection circuit. In addition, in the figures, the same symbols indicate the same or equivalent parts○

Claims (1)

[Claims] In a PLL circuit consisting of a reference signal oscillator, fixed frequency divider, phase comparator, and variable frequency divider, between each power supply voltage terminal and the power supply voltage supply terminal for supplying the power supply voltage to this power supply voltage terminal. A switch circuit that performs intermittent operation, a switch control circuit that turns on and off the switch of this switch circuit, and a phase difference detection circuit that generates the switch control circuit using the output signal of a phase comparator. Features an intermittent operation PLL circuit.