JPS59221034A - Frequency synthesizer - Google Patents

Abstract

PURPOSE:To obtain a frequency synthesizer having high stability and small power consumption by supplying the basic wave to a PLL circuit to stabilize the frequency and extracting the higher harmonic wave as an output. CONSTITUTION:The basic wave of a voltage control oscillator VCO10 is supplied to a prescaler 13 via an LPF21 of a demultiplexer 20 and has synchronism of phase with a reference oscillator 16. Thus the frequency of the VCO10 is stabilized. While the higher harmonic wave of the VCO10 is extracted to the outside as an output via an HFP22 of the demultiplexer 20. In such constitution, a low insertion loss is possible with LPF21 and HPF22 respectively despite a low level of no-load Q. Thus it is possible to reduce the loss caused by branching, and the output level of the VCO10 can be reduced. Then a frequency synthesizer having high stability and small current consumption is obtained since no multiplying circuit is needed.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a frequency synthesizer using a phase-locked loop circuit (PLL circuit).

Conventional configuration and its problems Figure 1 shows a conventional frequency synthesizer and its problems.
This is a circuit that combines multiple circuits. Voltage controlled oscillator (
(hereinafter abbreviated as YCO) 10 output u:, distributor 11
Accordingly, the signal is divided into the prescaler 13 side and the multiplier circuit 18 side. The output of vCOlo input to the grease scaler 13i 111j is sent to the prescaler 13 and the terminal 17.
The frequency is divided by a programmable divider 15 that divides the frequency according to frequency division ratio data applied to the frequency. The output of the programmable divider 15 is input to a phase detector (hereinafter abbreviated as PD) 14 together with the output of a reference oscillator 16 such as a temperature-compensated crystal oscillator, and the output of the PD 14 is inputted to d: the order # of these two input signals. 'A DC voltage appears proportional to the LJ difference. Then, only the DC component is extracted by the loop filter 12 and becomes the VCO1.

is added to control the oscillation frequency. This operation is P
This process is repeated until there is no difference in magnitude of 41J between the two input signals input to D14, and the oscillation frequency of Vcolo is locked to a constant value. The output of this locked vcolo is multiplied by a multiplication amount y618, and a desired harmonic is taken out as an output to the outside. This circuit can realize a frequency synthesizer even at high frequencies higher than the prescaler divided by 130 and 1 slope, but both the fundamental wave and harmonics can be
Since it includes a multiplier circuit 18 that handles 15!9, it has the disadvantage that it is sensitive to fluctuations in circuit constants and its operation becomes unstable with respect to changes in ambient temperature. Furthermore, the number of parts increases, leading to an increase in current consumption, making it unsuitable for devices that require low power consumption, such as mobile radios.

OBJECTS OF THE INVENTION The present invention has been made in view of the above-mentioned drawbacks, and provides a frequency synthesizer with a simple configuration and low power consumption even in the high frequency region of the prescaler frequency division limit plate, which cannot be realized with a direct frequency division synthesizer. This is what we are trying to provide.

Structure of the Invention In the present invention, the fundamental wave and harmonics of a voltage controlled oscillator are branched using a duplexer consisting of two or less types of filters, and the fundamental wave is input to a phase-locked loop circuit to generate a highly stable oscillator. The above objective is achieved by synchronizing the phase with the frequency and stabilizing the frequency, while outputting harmonics to the outside.

DESCRIPTION OF THE EMBODIMENTS A first embodiment of the present invention will be described below with reference to the drawings.

FIG. 2 is a block diagram of the frequency synthesizer in the first embodiment of the present invention. In Figure 2, vC
Since olo performs a nonlinear operation, it itself contains harmonics. The fundamental wave of VCOlo is input to the grease scaler 13 via a low-pass filter (hereinafter abbreviated as LPF) 21, which is a component of the branching filter 2o.
As explained in the figure, it is phase-locked to the reference excavator 16,
The frequency of VCOlo is stabilized. On the other hand, vC01
The zero harmonic is taken out as an output to the outside via a high-pass filter (hereinafter abbreviated as HPF) 22, which is another component of the duplexer 20.

According to the above configuration, the LPF 21 and HPF 22 can easily have low insertion loss even if the no-load Q is low, so the loss due to branching is greater than the conventional one that distributes the fundamental wave output of vCOlo one by one. can be made small, and the output level of VCOlo can be reduced.

Furthermore, since the multiplier circuit 18 shown in FIG. 1 is not included, it is possible to realize a frequency synthesizer that is stable and consumes little current. Note that the duplexer 20 consisting of this combination of filters 21 and 22 can be designed to have a cutoff frequency of the LPF 21 higher than the fundamental wave and a cutoff frequency of the HPF 22 lower than the desired harmonic. This is effective when the frequency interval is wide.

FIG. 3 shows a second embodiment of the invention. This embodiment differs from the configuration shown in FIG.
Instead of the duplexer 20 shown in the figure, an LPF 31 and a BPF
'32 constitutes the duplexer 30. Components with the same configuration as in Figure 2 are designated by the same numbers.

In the above configuration, the fundamental wave of vColo is inputted to the prescaler 13 via the LPF 31, which is a component of the duplexer 30, to stabilize the frequency, as in the embodiment described using FIG. .

On the other hand, the harmonics of vCO1o are taken out as an external output via a band pass filter (hereinafter abbreviated as BPF) 32, which is another component of the duplexer 30.

That is, according to the above configuration, the fundamental wave is passed through the LPF 31 with low insertion loss, while the harmonics are passed through the BPF 3 with good selectivity.
By configuring the output via 2, the vCo
It is possible to realize a frequency synthesizer that requires less lo output and has good spurious characteristics.

FIG. 4 shows a third embodiment of the invention. This embodiment differs from the configuration shown in FIG.
BPF41 and HPF4 are shown in the figure instead of the duplexer 20.
2 constitutes the duplexer 40. Furthermore, the second
Items with the same configuration as in the figure are designated by the same numbers.

In the above configuration, the fundamental wave of VCOlo is transmitted to the prescaler 13 via the 13PF 41, which is a component of the duplexer 40.
The frequency is stabilized. On the other hand, VCO1
The 0 harmonic is taken out as an external output via the HPF 42, which is another component of the duplexer 40.

According to the above configuration, the fundamental wave is passed through the PF14 with good selectivity, while the harmonics are passed through the H with low insertion loss.
By configuring the output through the PF 42, it is effective when harmonics are included in the range that can be divided by the prescaler 130, and a frequency synthesizer with less attenuation of the harmonic output can be realized.

FIG. 6 shows a fourth embodiment of the invention. The difference in this embodiment from the configuration shown in FIG. 2 is that two types of BPF51.52 are used instead of the duplexer 2o shown in FIG.
This is how the duplexer 60 is configured. Components having the same configuration as in FIG. 2 are given the same numbers. In the above configuration, vc.

10 fundamental waves and harmonics are both demultiplexed via BPF61.62, which is a component of the demultiplexer 5°. B.P.
The center frequency of F51 is set to the fundamental wave, and the center frequency of BPF52 is set to a desired harmonic.

In other words, the above configuration has good selectivity for both the fundamental wave and harmonics, and by passing the PF61.52'i, it is effective when harmonics are included in the frequency division range of the prescaler 10, and the spurious characteristics are reduced. A good frequency synthesizer is possible.

FIG. 6 shows a fifth embodiment of the invention. The difference in this embodiment from the configuration shown in FIG. 2 is that instead of the duplexer 20 shown in FIG.
(abbreviated as BSF) 61 and BPF 62 form a duplexer 6.
This is the point that made up o. Components with the same configuration as in FIG. 2 are designated by the same numbers.

In configuration 1, the fundamental wave of vColo is transmitted through the duplexer 60.
Prescaler 13 via BSF 61, which is a component of
The frequency is stabilized. On the other hand, vCO1
The 0 harmonic is extracted as an external output via the BPF 62, which is another component of the duplexer 60.

Note that at this time, the center frequencies of the BPF 61 and BSF 62 are set to desired harmonic frequencies.

According to the above embodiment, the fundamental wave is passed through the BSF61 with low insertion loss in the fundamental wave, while the harmonics are passed through the BSF61 with good 1 selectivity.
By outputting through the PF 62, the output of vcolo can be reduced, and a frequency synthesizer with good spurious characteristics can be realized.

FIG. 7 shows a sixth embodiment of the present invention. This embodiment differs from the configuration in FIG. 2 in that the duplexer To is composed of an FBSF 71 and an HPF 72 instead of the duplexer 20 shown in FIG. Components with the same configuration as in FIG. 2 are designated by the same numbers.

In the above configuration, the fundamental wave of vCOlo is input to the prescaler 13 via the BSF 71, which is a component of the duplexer To, and the frequency is stabilized. On the other hand, harmonics are
The signal is taken out as an external output via the HPF 72, which is another component of the duplexer 70. At this time, B
The center frequency of SF71 is set to the desired harmonic, and HP
The cutoff frequency of F72 is set lower than the desired harmonic.

As described above, according to this embodiment, the fundamental wave is passed through the BSF71, which has a small insertion loss in the fundamental wave, and the harmonics are passed through the HSF71, which has a small insertion loss.
By outputting through PFγ2, the output level of voolo can be reduced.

FIG. 8 shows a seventh embodiment of the present invention. The difference in this embodiment from the configuration shown in FIG. 2 is that two types of BSFBl, 82
This is how the duplexer 80 is configured. fr, items with the same configuration as in Figure 2 have the same number interest rate.

In the second embodiment, the fundamental wave and harmonics of vCOlo are both components of the demultiplexer 80, BSFal, 82.
It is demultiplexed via i. The center frequency of BSFB1 is set to a desired harmonic, and the center frequency of BSF82 is set to a fundamental wave.

As described above, according to this embodiment, since the insertion loss is small for both the fundamental wave and harmonic frequencies, vColo
It is possible to realize a frequency synthesizer that requires less output level and less attenuation of harmonic output.

FIG. 9 shows an eighth embodiment of the present invention. This embodiment differs from the configuration shown in FIG. 2 in that the duplexer 90 is composed of an LPF 91 and a BSF 92 instead of the duplexer 2Q shown in FIG. Components having the same configuration as shown in FIG. 2 are given the same numbers.

In the above configuration, the fundamental wave of vCOlo is input to the prescaler 13 via the LPF 91, which is a component of the duplexer 90, to stabilize the frequency. On the other hand, harmonics are
BSF 9 which is another component of the demultiplexer 90
It is taken out as an external output via 2 f and 1. In addition, at this time, the center frequency of BSF92 is the fundamental wave, and the LP
The cutoff frequency of F91 is set higher than the fundamental wave.

Second, according to the above embodiment, the output level of vCOLQ can be reduced by outputting the fundamental wave through the LPF 91 with low insertion loss and outputting the harmonic through the BSF 92 with low insertion loss at the harmonic frequency. At the same time, a frequency synthesizer with harmonic output with little attenuation can be realized.

FIG. 10 shows a ninth embodiment of the present invention.

The difference in this embodiment from the configuration shown in FIG. 2 is that instead of the duplexer 20 shown in FIG.
02 constitutes the duplexer 100. Components having the same configuration as in FIG. 2 are given the same numbers.

In the above embodiment, the fundamental wave of vCOlo is transmitted to the duplexer 10
The signal is input to the prescaler 13 via BPFlol, which is a component of 0, to stabilize the frequency. On the other hand, harmonics are generated by BSF102, another component of the demultiplexer.
It is taken out as an external output via . Note that at this time, the center frequencies of BPFlol and BSF 102 are set to the fundamental wave.

As described above, according to this embodiment, the fundamental wave has good selectivity and P
By outputting harmonics through BSF102, which has low insertion loss at harmonic frequencies,
It is possible to realize a frequency synthesizer that is effective when harmonics are included in the range that can be divided by the prescaler 130, and whose harmonic output is less attenuated.

Effects of the Invention As described in Section 2, the present invention splits the fundamental wave and harmonics of a voltage-controlled cape oscillator using a duplexer consisting of two or less types of filters, and splits the fundamental wave into a phase-locked loop circuit. By manually synchronizing the phase with a highly stable oscillator, and by configuring the harmonics to be taken out as output, (1) a stable frequency synthesizer with low power consumption that does not include a multiplier circuit; (2) It is possible to realize a frequency synthesizer that operates even if the output of the voltage-limited 1 oscillator is small and has good spurious characteristics.

(3) An effective frequency synthesizer can be realized even when harmonics are included in the frequency division range of Presque and -Ra.

(4) A frequency synthesizer with less attenuation of desired harmonic output can be realized.

Its industrial utility value is extremely large.

[Brief explanation of drawings]

Fig. 1 is a block diagram of a conventional frequency synthesizer using a multiplier circuit, and Figs.
- It is a block wiring diagram of the frequency synthesizer in 9th Example. 10... VCo, 12... Loop filter, 13... Prescaler, 14...
・PD, 16...Programmable debugging, 1
6...Reference oscillator, 1...Divide data input terminal, 20, 30.40° 50.60, 70, 8
0,90,100=-=brancher, 21.31.91...
...LPF, 22.42. 72...HPF, 32,41.51.52,6
2゜101...BPF, 61.71.81.8
2゜92.102・・・・・・BSF0 Name of agent Patent attorney Toshi Nakao and 1 other person 1st
Figure 5 Figure 7

Claims (1)

[Claims] The fundamental wave and harmonics of the voltage controlled oscillator are branched using a duplexer consisting of a filter of 2 or less, and the fundamental wave is input to a phase-locked loop circuit to synchronize the oscillator by about 4'lJ, A frequency synthesizer that extracts the harmonics as an output.