JPH01282926A - Phase locked oscillator - Google Patents

Abstract

PURPOSE:To eliminate noise from each power supply and to improve the noise characteristic of a phase locked oscillator by inserting and connecting a 3-terminal regulator to each power supply for a multiplier, a loop filter and a voltage controlled oscillator. CONSTITUTION:Three-terminal regulators 16, 17, 18 are connected respectively to power supply input terminals 13, 14, 15 for a multiplier 2, a loop filter 4 and a voltage controlled oscillator 5. That is, one of the 3-terminal regulators is connected to power input terminals 13, 14, 15, one of them is connected to the input terminals of the multiplier 2, the loop filter 4 and the voltage controlled oscillator 5, and one of them is connected to ground. The 3-terminal regulators are connected between each power supply input and each supply power to supply a power supply with low noise.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a phase-locked oscillator from the HF band to the microwave band, and particularly to a phase-locked oscillator with excellent noise characteristics.

(Prior art) Fig. 2 is a block diagram showing the configuration of a conventional phase-locked oscillator. A multiplier 3 that multiplies the output of the multiplier 2 and a phase (frequency) of the output of the voltage controlled oscillator 5 that oscillates at a higher frequency than the output frequency of the reference oscillator 1 and outputs a 1 phase difference signal. A comparator 4 is a loop filter that integrates the output of this phase comparator 3 and outputs a DC signal, and a voltage controlled oscillator 5 has an oscillation frequency controlled by the DC voltage of this loop filter 4 and outputs an oscillation output to an output terminal 6. Output.

In this case, the phase comparator 3 outputs an output proportional to the phase difference between the comparison reference frequency obtained by multiplying the output frequency of the reference oscillator 1 and the feedback signal of the output frequency from the voltage controlled oscillator 5. The harmonic components of this phase comparison output are removed by a loop filter 4, and the DC control signal (voltage) is sent to a voltage controlled oscillator 5.
Add to. This control direction always works to eliminate the phase difference and maintain the same phase, and as shown in FIG. 2, stabilizes the oscillation frequency f0 and improves the noise characteristics (CN ratio).

Figure 2 shows that when the voltage controlled oscillator 5 has noise characteristics as shown by curve 7, when the noise characteristics of other circuit parts are combined, the phase-locked oscillator has noise characteristics as shown by curve 8. .

(Problems to be Solved by the Invention) In the configuration of the phase-locked oscillator shown in FIG. 2, the load Q of the oscillator is a factor that affects the noise characteristics.

Multiplier 2. Three things are relevant: the quality of the power supplies for the loop filter 4 and the voltage controlled oscillator 5, and the design of the loop filter 4. Now, when considering the quality of the power supply,
Noise characteristics deteriorate due to noise such as power supply ripple.

Conventionally, as a countermeasure against this problem, for example, as shown in FIG. 4, a multiplier 2. LC filters 10, 11, 12 each comprising a large capacity capacitor C and a coil L were provided on the respective power input terminals 13, 14, 15 of the loop filter 4 and voltage controlled oscillator 5. However, this LC filter is large in size and has the disadvantage that reliability deteriorates as the capacitance of the capacitor changes over time.

The present invention is intended to solve these problems, and in particular aims to reduce the noise generated in the power supply and eliminate it using a stable three-terminal regulator, thereby providing a phase-locked oscillator with excellent noise characteristics. .

(Means for Solving the Problems) In order to achieve the above object, the present invention provides a reference oscillator that generates a reference frequency, a multiplier that multiplies the reference frequency of this reference oscillator, and an output frequency of this multiplier and a A phase difference comparator that compares the phase with the output frequency of a voltage controlled oscillator that oscillates at a higher frequency than the reference frequency of the reference oscillator and outputs a phase difference signal, and removes harmonic components from the output signal of this phase difference comparator. A phase synchronized oscillator comprising a loop filter and the voltage controlled oscillator is characterized in that a three-terminal regulator is inserted and connected to each power source of the multiplier, the loop filter, and the voltage controlled oscillator.

(Function) With the above configuration, the present invention removes noise from each power source of the multiplier, loop filter, and voltage controlled oscillator, and improves the noise characteristics of the phase synchronized oscillator as a whole.
It is possible to achieve miniaturization, integration, cost reduction, and improvement in reliability.

(Embodiment) FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention, and the same numbers and symbols as in FIG. 4 indicate the same things. As shown in the figure, the configuration is such that small three-terminal regulators 16, 17, and 18 are connected to power input terminals 13, 14, and 15 of the multiplier 2, loop filter 4, and voltage-controlled oscillator 5, respectively. That is, one of the three terminals is connected to the power input terminal, one is connected to the input terminal of each circuit, and one is grounded.

By connecting a small three-terminal regulator between each power input section and each power supply, it is possible to supply power with low noise, and achieve phase synchronization as shown in curve 9 in Figure 3. The noise characteristics of the oscillator can be obtained, and the conventional (curve 8)
) was significantly improved compared to

(Effects of the Invention) As described above, according to the present invention, by providing a three-terminal regulator between the power supply and the power input section of each part, deterioration of the noise characteristics of the oscillator due to power supply noise can be removed with a simple circuit. This has the effect of being able to.

Furthermore, by reducing the large capacitance capacitor used to remove power supply noise, the device can be made smaller, and there is no problem of capacitance change, which improves long-term reliability. This has the effect of realizing integrated circuits.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention, FIGS. 2 and 4 are block diagrams showing the configuration of a conventional phase-locked oscillator, and FIG. 3 is a block diagram showing the configuration of a conventional phase-locked oscillator. It is a noise characteristic diagram. 1... Reference oscillator, 2... Multiplier, 3... Phase comparator, 4... Loop filter, 5... Voltage controlled oscillator, 6... Oscillation output terminal, 13.14.15・
...Power input terminal. 16, 17.18... Three terminal regulator.

Claims (1)

[Claims] A reference oscillator that generates a reference frequency, a multiplier that multiplies the reference frequency of this reference oscillator, and a phase between the output frequency of this multiplier and the output frequency of a voltage controlled oscillator that oscillates a frequency higher than the reference frequency of the reference oscillator. In the phase synchronized oscillator, the phase synchronized oscillator is composed of a phase difference comparator that compares and outputs a phase difference signal, a loop filter that removes harmonic components of the output signal of the phase difference comparator, and the voltage controlled oscillator, the multiplier; A phase synchronized oscillator characterized in that a three-terminal regulator is inserted and connected to each power supply of a loop filter and a voltage controlled oscillator.