JPH01160143A - Modulator-demodulator circuit - Google Patents

Abstract

PURPOSE:To simplify the maintenance and manufacture management and to attain small sized circuit by using a surface acoustic wave device provided with 1st-3rd interdigital electrodes so as to form a distribution delay circuit and specifying the arrangement of each interdigital electrode. CONSTITUTION:The distribution delay circuit 11 is formed by using the surface acoustic wave device SAW device) 1 provided with the three interdigital electrodes 101-103. Then a 1st delay represented by the sum of a delay corresponding to one bit of data signal and a phase delay of + or -(2n-1)pi/4(where n=1, 2, 3, 4-) is applied to a signal propagated from a 1st interdigital electrode 101 to a 2nd interdigital electrode 102 and a 2nd delay whose phase differs by + or -pi/2 from the 1st delay is applied to the signal propagated from the 1st interdigital electrode 101 to a 3rd interdigital electrode 103 through the arrangement of the interdigital electrodes 101-103. Thus, the modulation and demodulation by a 4-phase modulation system are implemented by a common circuit and the small sized circuit is attained, and the manufacture of the circuit and maintenance and inspection are simplified.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a modulation/demodulation circuit, particularly to improvements in a delay detection demodulation circuit and a modulation circuit using a four-set phase modulation method.

[Prior art] Conventionally, in a modulation circuit that performs four-set phase modulation, the second
The one shown in the figure is known, and the four
A circuit as shown in FIG. 3 is known as a demodulation circuit for demodulating a set phase modulation signal.

The four-set phase modulation circuit shown in FIG. 2 includes a hybrid 2a,
It is configured using two sets of mixers 3a and 3b, a carrier signal generator 4, a hybrid 2b, and a phase shifter 8.

In the figure, 6a is a data signal, 6b is a data signal which is a component orthogonal to this, and 201 is a four-set phase modulation signal.

In this modulation circuit, the signal output from the carrier signal generator 4 is divided into two by the hybrid 2b, one is input to the mixer 3a, and the other is phased by π/2 by the phase shifter 8. , is input to mixer 3b.

When data signals 6a and 6b are input to this modulation circuit, these input signals 6a and 6b are modulated by mixers 3a and 3b, and then input to hybrid 2a.

Then, the hybrid 2a is connected to the mixer 3a in this way.
, 3b are combined to generate 4 sets of phase extension signals 2
It is output as 01.

Furthermore, the conventional demodulation circuit shown in FIG.
1, mixers 3a and 3b, and a distribution delay circuit 11, and is configured as a delay detection demodulation path for demodulating four sets of phase modulated signals.

When a four-phase phase modulation signal 201 is input to this demodulation circuit, this signal 201 is divided into three signals 210, 211 and 212 by the hybrid 2a.

Of the three distributed signals, one signal 210 is input to the distribution delay circuit 11, subjected to distribution delay, becomes a reference signal for differential detection, and is input to each mixer 3a, 3b. Here, the distribution delay circuit 11 is composed of a hybrid 2b, two delay circuits 7, and a π/2 phase shifter 8.

Then, in the delay circuit 7, a delay equal to 1 bit of the data signal and ±(2n-1)π/4 (where n=1.2.3...
・ ) phase delay is performed.

Further, the other two signals 211 and 212 among the three divided signals output from the hybrid 2a are input to mixers 3a and 3b, respectively, and the data signals 6a and 6b are input to mixers 3a and 3b, respectively.
It is demodulated and output as

[Problems to be Solved] However, in such conventional circuits, when configuring a transmitting/receiving device, it is necessary to separately provide a modulation circuit shown in FIG. 2 and a demodulation circuit shown in FIG. Ta.

For example, when configuring a simplex type transmitting/receiving device, this not only becomes an obstacle when downsizing the entire device, but also when configuring other duplex type transmitting/receiving devices, There was a problem in that a separate circuit had to be provided for the device, which required complicated work both in terms of manufacturing and maintenance of the device.

Furthermore, when performing this type of phase modulation or demodulation, the delay circuits and phase shifters used for this require high precision, so if such delay circuits and phase shifts are constructed with coils, capacitors, etc. There was a problem in that it was necessary to make fine adjustments to achieve accuracy.

The present invention has been made in view of such conventional problems, and its purpose is to realize a demodulation circuit that can perform modulation and demodulation of a four-set phase modulation method using a common circuit.

[Means for Solving Problems 1] In order to achieve the above object, the present invention includes a hybrid that distributes and combines modulated signals, two sets of mixer circuits that convert data signals and modulated signals input to the hybrid, and a carrier wave. a carrier wave signal generator that outputs a signal, a switching circuit that selectively outputs either the distributed output of the hybrid or the output of the carrier signal generator, and a mixer of the 2ffi that distributes and delays the output of this switching circuit. a distribution delay circuit that outputs the output signal to the circuit, and the distribution delay circuit includes a first interdigital electrode into which the output signal of the switching circuit is input, and a distribution delay circuit that outputs the distribution delay signal to the two mixer circuits. formed using a surface acoustic wave device comprising a second interdigitated electrode and a third interdigitated electrode, each outputting a waveform that propagates from the first interdigitated electrode to the second interdigitated electrode. The resulting signal has a delay equivalent to 1 bit of the data signal and ±(2n-1)π/4 (where n=1.2...
3...), and the signal propagated from the first interdigital electrode to the third interdigital electrode has a first delay and a phase delay of are in phase with each other ±π
In this configuration, each interdigital electrode is arranged so that a second delay different by /2 is applied.

[Example] Next, a preferred example of the present invention will be described based on the drawings. Incidentally, members corresponding to those of the conventional apparatus shown in FIGS. 2 and 3 are designated by the same reference numerals, and their explanations will be omitted.

FIG. 1 shows a preferred embodiment of the modulation/demodulation circuit according to the present invention, and the modulation/demodulation circuit of the embodiment includes a hybrid 2, a carrier signal generator 4, and two mixers 3a and 3b.
, a switching circuit 5 , and a distribution delay circuit 11 .

In the present invention, this distributed delay circuit 11 includes three interdigital electrodes (hereinafter referred to as IDT) 1o1.102 and 1.
Surface acoustic wave device (hereinafter referred to as SAW device) having 03
1, and the signals input to the first IDT10I are input from the second IDT102 and the third IDT103, which are located at different positions, respectively, to the first
and a second delay.

Here, if the first delay is T1 and the second delay is T2, the delays are expressed by the following equations.

TI = TO ± (2n-1)/4 T2 = Ti ± (π/2) However, n = 1.2.3... TO = delay equivalent to 1 bit of data signal The device shown in Fig. 1 has n = 2, and each IDTl0I, 102.103 is installed so that the first delay T1 and the second delay T2 are given by the following equation.

TI =TO+ (3/4)π T2 =TO+ <5/4)π As described above, the SAW device 1 used in the present invention has the distribution function and the delay necessary for delayed detection by the arrangement of the three IDTs 101, 102, and 103. It is possible to demonstrate the functions. Moreover, this SAW device 1 can be formed as a single element if necessary.

Further, the switching circuit 5 selects either the signal 210 distributed and output from the hybrid 2 or the carrier signal output from the carrier signal generator 4, and outputs it to the first IDTl0I of the SAW device 1. It is formed like this.

The present embodiment has the above configuration, and its operation will be explained next.

First, when the device of this embodiment is used as a modulation circuit, the switching circuit 5 is controlled so that the output of the carrier signal generator 4 is input to the first IDTl0I.

By doing so, the carrier wave signal is divided into two by the SAW device 1 and supplied to each mixer 3a and 3b as signals that differ by π/2 from each other.

At this time, when the data signal 6a and the data signal 6b are applied to the mixer 3b, the input signals 6a and 6b are phase modulated and output to the hybrid 2.

In this way, the hybrid 2 connects each mixer 3
The signals output from a and 3b are combined and output as a modulated signal 201 subjected to quadrature phase modulation.

In this way, the circuit of this embodiment can be used as a modulation circuit.

Furthermore, when the circuit of this embodiment is used as a demodulation circuit, the switching circuit 5 is controlled so that the output signal of the hybrid 2 is input to the first IDTl0I. In this way, when the modulation signal 201 subjected to quadrature phase modulation is input to the hybrid 2, one signal 210 of the three signals divided into three and output from the hybrid 2
is input to the first IDTl0I.

Then, the SAW device 1 applies a delay equal to 1 bit of the data signal necessary for delayed detection to the signal 210 inputted in this way, as well as (3/4)π and (5/4) respectively.
) is distributed into two signals with a phase delay of π. These two signals are outputted to mixer 3a and mixer 3b, respectively, as reference signals for differential detection.

At this time, the remaining two signals 211 and 212 of the three signals distributed by the hybrid 2 are input to the mixers 3a and 3b, respectively.

Therefore, mixer 3a and mixer 3b perform delay detection on the remaining two signals 211 and 212, respectively, of the three divided signals outputted from hybrid 2, and output them as data signal 6a and data signal 6b.

In this way, the circuit of this embodiment can be used as a demodulation circuit.

Furthermore, in the present invention, the mixers 3a and 3b can each be configured with the same circuit, so the mixers 3a and 3b can be formed using a general double-balanced mixer.

An example of such a mixer is shown in FIG. 4, and when this mixer is used in the modulation/demodulation circuit according to this embodiment, the RF terminal 31 is connected to the hybrid 2, and the LO terminals 33 and 34 are connected to the hybrid 2. Connect to SAW device 1 and connect to RF terminal 32
may be used as an input terminal for a data signal representing the states of "1" and "0" with positive and negative currents.

Furthermore, in this embodiment, the amount of delay necessary for modulation and demodulation is obtained by the SAW device 1, but the accuracy of this delay is
It is determined by the accuracy of the arrangement of T(101, 102, 103).

The arrangement of the IDTs 101, 102, and 103 can be performed with high precision using integrated circuit printing technology, so if the SAW device 1 is formed as a single element, an element with an accurate amount of delay can be obtained at the manufacturing stage. It is possible to eliminate the need for adjustment of the modulation/demodulation circuit.

[Effects of the Invention] As explained above, according to the present invention, a surface acoustic wave device is used as a distribution delay circuit, and modulation and demodulation can be switched by a switching circuit. When incorporated into a device, the entire device can be significantly downsized, and the number of parts can be reduced, so manufacturing and maintenance management can be simplified.

Furthermore, according to the present invention, since the surface acoustic wave device constituting the distribution delay circuit can be formed as a single element as necessary, there is no need for adjustment at the manufacturing stage. Cost reduction can be achieved.

[Brief explanation of the drawing]

FIG. 1 is a block circuit diagram showing a preferred embodiment of a modulation/demodulation circuit according to the present invention, FIG. 2 is a block circuit diagram showing an example of a conventional modulation circuit, and FIG. 3 is a block diagram showing an example of a conventional demodulation circuit. Circuit Diagram FIG. 4 is a block circuit diagram of a mixer circuit used in the circuit shown in FIG. 1: Surface acoustic wave device 2: Hybrid 3a, 3b: Mixer 4: Carrier signal generator 5: Switching circuit 6a, 6b = data signal 7: Delay circuit 8: Phase shifter 11: Distribution delay circuit 101.102.1o3 : Cross-finger electrode 201: 4-phase phase modulation signal

Claims (1)

[Claims] (1) A hybrid that distributes and combines modulated signals, two mixer circuits that convert data signals and modulated signals input to the hybrid, a carrier signal generator that outputs carrier signals, and a distributed output of the hybrid. and an output of the carrier wave signal generator; and a distribution delay circuit that distributes and delays the output of the switching circuit and outputs the output to the two mixer circuits, respectively. The distribution delay circuit includes a first interdigital electrode into which the output signal of the switching circuit is input, a second interdigital electrode and a third electrode which respectively output the distribution delay signal to the two mixer circuits. A surface acoustic wave device is formed using a surface acoustic wave device having interdigitated finger electrodes, and a signal propagated from the first interdigitated finger electrode to the second interdigitated finger electrode has a delay equivalent to one bit of the data signal. and,
A first delay expressed as the sum of phase delays of ±(2n-1)π/4 (where n=1, 2, 3...) is applied, and the first
The signals propagated from each interdigital electrode to the third interdigital electrode are subjected to a second delay which is ±π/2 in phase with respect to the first delay. A modulation/demodulation circuit characterized in that electrodes are arranged.