JPH02150112A - 90× phase shifter - Google Patents

Abstract

PURPOSE:To inexpensively obtain a 90 deg. phase shifter with high accuracy with simple constitution by taking out a second harmonic via a band-pass filter, and performing inversion, non-inversion and 1/2-frequency division at an amplifier circuit and a filp-flop. CONSTITUTION:The fundamental wave f1 of a voltage controlled oscillator 11 is supplied to a synthesizer 12 and a reception demodulation part 13, and simultaneously, the second harmonic f2 of the fundamental wave f1 is supplied to the amplifier circuit 15 via the band-pass filter 14. And inversion and non- inversion output obtained at the amplifier circuit 15 are supplied to the flip-flops 16 and 17, and are 1/2-frequency divided, and a signal having a phase difference of 90 deg. is taken out, then, it is outputted to a modulator 20. In such a way, it is possible to obtain the 90 deg. phase shifter with high accuracy with the simple constitution and as attaining the reduction of power consumption.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is directed to generating two waves with a phase difference of exactly 90 degrees from the second harmonic of the fundamental frequency generated in a voltage controlled oscillator of a radio.
This relates to a 90 degree phase shifter that outputs two signals.

[Prior Art] Fig. 6 is a block connection diagram showing a conventional 90-degree divider that takes out two signals having a phase difference of 90 degrees. In the figure, 1.2 is a D flip-flop, which is connected to a data terminal. When a “H” level signal is input to the trigger terminal T while a “H°°” or “°°L” level signal is being applied,
Information of the D terminal is output to the Q terminal, and a signal obtained by inverting the signal of the D terminal is output to the one-way terminal. 3 is a clock input terminal, and 5.7 is an output terminal.

Next, the operation will be explained with reference to the timing chart shown in FIG. First, when the clock pulse shown in FIG. 7(a) is input to the clock input terminal 3, the signals shown in FIG. 7(b) and (c) are output to the Q terminal of each D flip-flop 1 and 2. , a one-cycle waveform is output to each Q terminal using the four clock pulses.

Now, if we pay attention to the signal waveforms of the two Q terminals, one period of the clock pulse is 1/1 of the output waveform of each Q terminal.
There are four periods, and the angle is π/2 radian or 90 degrees. Furthermore, since the phase difference between the output waveforms of each Q terminal is a shift of one period of the clock pulse waveform, a phase difference of 90 degrees can be extracted.

[Problem to be solved by the invention]

Since the conventional 90-degree phase shifter is configured as described above, in order to extract the 90-degree phase difference of the frequency f, which is the fundamental wave, a clock pulse with a frequency four times the frequency f is required. In addition to the increased power consumption in the flip-flop 1.2, there were other problems such as it became difficult to extract four times the frequency as the frequency f became higher.

As an approximation technique, there is one described in 1981 IEICE Communications Division National Conference No. 473.

This invention was made to solve the above-mentioned problems, and uses the second harmonic output from the voltage controlled oscillator of a wireless device, which has not been used in the past, as the original signal, and converts it to 1/2.
By dividing the frequency, it is possible to reduce current consumption while maintaining stable 9
The object of the present invention is to obtain a 90-degree phase shifter that can extract an output signal with a 0-degree phase difference.

[Means for Solving the Problems] A 90 degree phase shifter according to the present invention extracts the second harmonic from a voltage controlled oscillator separately from the fundamental wave through a bandpass filter, and extracts the second harmonic from the voltage controlled oscillator separately from the fundamental wave. , a non-inverted signal and an inverted signal having a phase difference of 90 degrees with respect to the fundamental wave are extracted through an amplifier circuit and a flip-flop.

[Effect]

The amplifier circuit and two flip-flops of the present invention divide the second harmonic non-inverted signal and inverted signal oscillated by the voltage controlled oscillator into 1/2, and divide the frequency of the second harmonic non-inverted signal and the inverted signal into 90 degrees, which is equal to the fundamental wave of the voltage controlled oscillator. It acts to extract a frequency output with a phase difference.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings. 1st
In the figure, reference numeral 11 denotes a voltage controlled oscillator ##≠PO constituting the 90-degree phase shifter 30, which can change the oscillation frequency according to a control voltage input from the outside.

The voltage controlled oscillator 11 of the radio has a very stable frequency.
Oscillates a highly selective frequency. This voltage controlled oscillator 1
As shown in FIG. 2, the oscillation spectrum of No. 1 oscillates at a frequency (harmonic) that is N times the fundamental frequency, and has high selectivity (proportional to the center frequency Nfl with respect to Δf). This voltage controlled oscillator 11 normally outputs only the fundamental wave f1 shown in FIG. Phase shift and take out. Reference numeral 14 denotes a bandpass filter that selectively extracts the second harmonic f2 for phase shifting by 90 degrees, as shown in FIG. In addition, in the frequency spectrum, as shown in Figure 2, there is a second harmonic f between the fundamental wave f1 and the third harmonic f3.
2, the bandpass filter 14 has a wide bandwidth of f1/2.

Reference numeral 15 denotes an amplifier circuit as a buffer circuit that amplifies the second harmonic f2 or transmits the signal to the flip-flop at the subsequent stage. Note that the characteristics of this amplifier circuit 15 may be determined by removing the band-pass filter 14 at the previous stage and giving this circuit a band-pass filter characteristic. Here, this amplifier circuit 15
This is a differential amplifier circuit that simultaneously takes out inverted and non-inverted output waveforms as outputs with little difference in delay time.

16.17 are flip-flops such as JK type and D type.
The output of the amplifier circuit 15 is divided into 1/2.

A modulator 20 receives the 90 degree phase difference signal from the flip-flops 16 and 17 and performs modulation, and the frequency is fl.

On the other hand, 12 is a synthesizer including a voltage controlled oscillator 11, a prescaler 23, a frequency divider 24, and phase comparator circuits 2 and 6.
and a temperature compensated oscillator 25, and functions as a frequency stabilizing circuit according to the channel control frequency. Also, 1
3 is a reception demodulation section, which mixes the reception frequency f11 and the output frequency f+ of the voltage controlled oscillator 11 to extract the frequency fII-f.

Next, the operation will be explained. First, in the synthesizer 12, the output frequency f1 of the voltage controlled oscillator 11 is received, the frequency is divided by the prescaler 23, and the frequency divider 24 is fixed to a frequency division ratio according to the channel control signal to perform frequency division.
The phase comparison circuit 26 performs a phase comparison (frequency comparison) between this frequency-divided output and the output of the temperature compensation oscillator 25. The oscillation frequency of the voltage controlled oscillator 11 is controlled based on the output according to the phase difference, and a stable oscillation frequency is output as the synthesizer 12.

Further, as shown in the frequency spectrum shown in FIG. 2, the voltage controlled oscillator 11 outputs a signal having a frequency of 1 N times as a fundamental wave, and has a very high selectivity proportional to f1/Δf. In this invention, in the output waveform diagram of the voltage controlled oscillator 11,
The fundamental wave fl is taken into the synthesizer 12 and the reception demodulator 13, and the frequency f is subtracted from the reception frequency f.

The f+ frequency is extracted through the mixer 27 of the receiving demodulator 13.

In addition, 9 including the voltage controlled oscillator 11 of the synthesizer 12
The 0 degree phase shifter 30 extracts the second harmonic f, which is twice the frequency of the fundamental wave f1, from the waveform shown in FIG. 2 generated by the voltage controlled oscillator 11 through the bandpass filter 14. This second harmonic f2 is a fundamental wave and has a stable frequency with high selectivity like the first harmonic, and if the second harmonic f2 can be amplified by the amplifier circuit 15 and the flip-flops 16 and 17 can be driven, even if the amplification degree is 1 times or less. Good), Figure 3 (a), (b
), non-inverted and inverted signals from the second harmonic f2 are output from the non-inverted output terminal 31 and the inverted output terminal 32.

The flip-flops 16.17 receive these signals and output the signals shown in FIGS. 3(C) and 3(d) to the output terminals 18.19. The signal waveforms shown in FIGS. 3(c) and 3(d) have the frequency of the fundamental wave f1, and have a phase difference of 90 degrees with respect to the frequency of the fundamental wave f1.

In this way, since the voltage controlled oscillator 11 outputs only N times the fundamental wave f1 at a very stable frequency, even if the filter characteristics of the bandpass filter 4 are a little bad, the characteristics can pass even the f2 region. For example, the second harmonic f2 in Fig. 3
The waveform is close to a sine wave, and there is no difference in delay time between inverted and non-inverted waveforms. Furthermore, since the flip-flops 16 and 17 use the same circuit, a highly accurate 90 degree phase shifter can be provided.

As described above, in the present invention, the fundamental wave f1 of the voltage controlled oscillator 11 is supplied to the synthesizer 12 and the reception demodulator 13, and at the same time, the second harmonic wave f2 of the fundamental wave f1 is supplied to the amplifier circuit 15 through the bandpass filter 14. , by supplying the inverted and non-inverted output obtained from this amplifier circuit 15 to the flip-flop 16°17 and dividing the frequency by l/2, 90
A signal having a phase difference of degrees is extracted and outputted to the modulator 20.

In the above embodiment, the amplifier circuit 15 outputs two outputs, an inverted signal and a non-inverted signal, but as shown in FIG.
The same effect as in the above embodiment can be obtained by taking out only the outputs of the flip-flops 16 and 17 and operating the outputs of the flip-flops 16 and 17 so that one falls and the other rises. Here, 33 is a flip-flop that operates in a falling or rising direction opposite to that of the flip-flop 16.

Further, in the embodiment of FIG. 4, two flip-flops 16
．． Although the master flip-flop 34 and the slave flip-flop 35 are connected in series as shown in FIG.
It is also possible to extract a degree phase difference signal, and the same effect as in the above embodiment can be obtained.

[Effects of the Invention] As described above, according to the present invention, the second harmonic in a voltage controlled oscillator of a wireless device, which has not been used in the past, is extracted through a bandpass filter, and further inverted using an amplifier circuit and a flip-flop. Since the structure is configured to perform non-inversion and 1/2 frequency division, there is an effect that a highly accurate 90-degree phase shifter can be realized with a simple structure and at low cost.

In addition, if such a 90 degree phase shifter is used, a frequency f having a 90 degree phase difference is created from f2 which is twice the output frequency f1 of the voltage controlled oscillator, and the frequency f++ entering the reception demodulator and the above By mixing f,
This has the effect that the frequency can be lowered (f++-fl) and a radio device whose circuit can be easily simplified.

[Brief explanation of the drawing]

Figure 1 is a block connection diagram showing a 90 degree phase shifter according to an embodiment of the present invention, Figure 2 is a frequency spectrum diagram of the oscillation signal of the voltage controlled oscillator, and Figure 3 is a signal diagram of each part of the circuit in Figure 1. A timing chart showing waveforms, Fig. 4 is a block connection diagram showing another embodiment of a 90 degree phase shifter, and Fig. 5 shows a 90 degree phase shifter.
FIG. 6 is a block connection diagram showing still another embodiment of the degree phase shifter; FIG. 6 is a block connection diagram showing a conventional 90 degree divider; FIG.
This figure is a timing chart showing signal waveform diagrams of each part in FIG. 6. 11 is a voltage controlled oscillator, 14 is a band pass filter, 15 is an amplifier circuit, 16.1
7.33 and 34.35 are flip-flops. In addition, is shown. In the figure, the same symbols are the same.

Claims (1)

[Claims] A voltage controlled oscillator of a radio device that generates a fundamental wave and a second harmonic of the fundamental wave; a bandpass filter that extracts the second harmonic separately from the fundamental wave; and a bandpass filter that extracts the second harmonic separately from the fundamental wave; A 90 degree phase shifter comprising an amplifier circuit and a flip-flop for extracting a non-inverted signal and an inverted signal having a phase difference of 90 degrees with respect to the fundamental wave from the second harmonic.