JP2001320430A - Ask modulator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an ASK(Amplitude Shift Keying) modulator that can obtain a sufficiently higher and proper modulation factor by suppressing the modulation factor from getting higher more than required due to variations in FETs. SOLUTION: The ASK modulation circuit employing FETs adopts a multi- stage connection configuration to obtain a larger modulation factor by improving the isolation at carrier interruption. Furthermore, by leaking part of a received carrier to an output side at al times a pass loss at carrier interruption is made constant and a proper modulation factor is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to ASK (Amplit)
The present invention relates to an ASK modulator used for a device that performs communication using a ude shift keying (modulation) method.

[0002]

2. Description of the Related Art FIG. 5 shows a conventional AS shown in, for example, IEICE Technical Report "Vol. 98 No. 518 (published on Jan. 21, 1999), pp. 47-50".
FIG. 3 is a circuit configuration diagram of a K modulator. In FIG. 5, 1 is a carrier input terminal, 2 is a baseband signal input terminal, and 3 is A
An SK modulated wave output terminal, 4 a matching circuit for impedance-converting the carrier input from the carrier input terminal 1;
Reference numeral 6 denotes a matching circuit for converting the impedance of the ASK modulated wave, 7 denotes a matching circuit 4 connected to a first gate 13, a baseband signal input terminal 2 connected to a second gate 14, and a matching circuit 6 connected to a drain 15. Is connected, source 1
Reference numeral 6 denotes a grounded dual gate FET. 9 is AS
A stabilization circuit that operates a dual-gate FET functioning as a K modulation circuit in a stable state.
It is connected to the first gate 13 and drain 15 of T7.

Next, the operation will be described. The carrier input from the carrier input terminal 1 is impedance-converted by the matching circuit 4 to prevent the input carrier from being reflected by the dual-gate FET 7 and input to the first gate 13 of the dual-gate FET 7.

Here, the dual gate FET 7 has a first
The dual gate FET 7 controls the current flowing from the drain 15 to the source 16 in accordance with the voltage input from the gate 13 and the second gate 14. The dual gate FET 7 inputs the carrier through the matching circuit 4 to the first gate 13. ASK modulation is performed by inputting the baseband signal from the baseband signal input terminal 2 to the second gate 14 and controlling the carrier with the baseband signal. The ASK modulated wave is output through the drain 15, impedance-converted by the matching circuit 6, and output from the modulated wave output terminal 3.

Further, by connecting the stabilizing circuit 9 between the first gate 13 and the drain 15 of the dual gate FET 7, A
The SK modulated output is fed back to the first gate 13, and the modulation circuit can be operated in a stable state.

[0006]

Since the conventional ASK modulator is configured as described above and performs modulation using the dual gate FET 7, sufficient isolation cannot be obtained when the carrier is cut off depending on the variation of the dual gate FET 7. In addition, there is a problem that the ASK modulated wave cannot obtain a sufficiently large modulation factor. Also, an ASK modulated wave having an unnecessarily high degree of modulation has a problem in that the off-level time during demodulation becomes short, making it difficult to detect, increasing the error rate, or not being able to detect at all.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has as its object to provide an ASK modulator capable of sufficiently increasing the modulation factor of an ASK modulated wave. In addition, AS is more than necessary
An object of the present invention is to suppress the K modulated wave from obtaining a high modulation degree and obtain an ASK modulator having a suitable modulation degree.

[0008]

An ASK modulator according to the present invention obtains an ASK modulated wave having a high degree of modulation by using an ASK modulation circuit using FETs in a multi-stage configuration.

ASK is connected to each FET connected in multiple stages.
Providing a stabilizing circuit for feeding back the modulated wave output to the gate to which the carrier is input allows the ASK modulation circuit to operate in a stable state.

Further, by providing a leaking means for constantly leaking a part of the input carrier to the output side, the output signal level when the carrier is cut off is kept constant, so that the ASK modulated wave having an appropriate modulation degree can be converted. What you get.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. Embodiment 1 FIG. FIG. 1 is a circuit diagram showing an ASK modulator having a two-stage connection configuration according to Embodiment 1 of the present invention.
In FIG. 1, reference numeral 1 denotes a carrier input terminal, 2 denotes a baseband signal input terminal, 3 denotes a modulated wave output terminal, 4 denotes a matching circuit for impedance-converting a carrier input from the carrier input terminal 1, and 5 denotes a first stage ASK modulated. Circuit and second stage A
An inter-stage matching circuit with the SK modulation circuit, 6 a matching circuit for impedance-converting the ASK modulated wave, 7 a first gate 1
3 is connected to the second gate 14, the baseband signal input terminal 2 is connected to the second gate 14, the interstage matching circuit 5 is connected to the drain 15, and the source 16 is grounded.
It is a dual gate FET that functions as an SK modulated circuit. Reference numeral 8 denotes a first gate in which the interstage matching circuit 5 is connected, the second gate 18 is connected to the baseband signal input terminal 2, the drain 19 is connected to the matching circuit 6, and the source 20 is grounded. It is a dual gate FET that functions as a two-stage ASK modulation circuit.

Next, the operation will be described. The carrier input to the carrier input terminal 1 is impedance-converted by the matching circuit 4 to prevent the input carrier from being reflected by the dual-gate FET 7 and input to the first gate 13 of the dual-gate FET 7.

Here, the dual gate FET 7 has a first
The dual gate FET 7 controls the current flowing from the drain 15 to the source 16 in accordance with the voltage input from the gate 13 and the second gate 14. The dual gate FET 7 inputs the carrier through the matching circuit 4 to the first gate 13. The baseband signal from the baseband signal input terminal 2 is input to the second gate 14, the carrier is controlled by the baseband signal to perform ASK modulation, and the ASK modulated wave is output through the drain 15.

The ASK modulated wave output from the drain 15 of the dual-gate FET 7 is impedance-converted by the inter-stage matching circuit 5 to prevent reflection by the dual-gate FET 8 and to be applied to the first gate 17 of the dual-gate FET 8. Is entered. The dual gate FET 8 transmits the ASK modulated wave through the inter-stage matching circuit 5 to the first gate 17.
At the same time, the baseband signal from the baseband signal input terminal 2 is input to the second gate 18 to perform ASK modulation, and the ASK modulated wave is output through the drain 19. The ASK modulated wave is impedance-converted by the matching circuit 6 and output from the modulated wave output terminal 3.

That is, in the first embodiment, the carrier through the matching circuit is input to the first gate of the dual gate FET, the baseband signal is input to the second gate, and the ASK
ASK which outputs a modulated wave from a drain, converts impedance through a matching circuit, and outputs from a modulated wave output terminal
By using a multi-stage configuration of the modulation circuit, A
An SK modulated wave can be obtained.

As described above, according to the first embodiment, the ASK modulated wave ASK-modulated by the dual-gate FET 7 functioning as the first-stage ASK modulation circuit is converted to the dual-gate FET 8 functioning as the second-stage modulation circuit. As an input, the second-stage ASK modulation circuit further performs ASK modulation, so that sufficient isolation is obtained when the carrier is cut off. Therefore, an ASK modulated wave having a higher modulation degree than the ASK modulator having a single-stage configuration. Can be obtained.

Embodiment 2 FIG. FIG. 2 is a circuit diagram showing an ASK modulator having a two-stage connection configuration according to a second embodiment of the present invention. 2, the same parts as those in the first embodiment shown in FIG. 1 are denoted by the same reference numerals, and the description thereof will be omitted. As a new code, 9 is a stabilizing circuit for operating the modulation circuit in a stable state, and is connected to the first gate 13 and the drain 15 of the dual gate FET 7. Reference numeral 10 denotes a stabilizing circuit that operates the modulation circuit in a stable state, and is connected to the first gate 17 and the drain 19 of the dual gate FET 8.

Next, the operation will be described. In the circuit configuration shown in FIG. 2, the same operation and effect as those of the first embodiment are obtained, and the ASK modulated output from the drains 15 and 19 of the dual gate FETs 7 and 8 is obtained by connecting the stabilizing circuits 9 and 10. Feedback is applied to the first gates 13 and 17, respectively, and the modulation circuit can be operated in a stable state.

Therefore, according to the second embodiment, a sufficient degree of modulation can be obtained by providing two stages of ASK modulation circuits for stable operation.

Embodiment 3 Next, F used for the modulation circuit
An embodiment will be described in which an ASK modulated wave having an appropriate degree of modulation can be obtained in a case where an unnecessary degree of modulation is obtained due to variation in ET. FIG. 3 is a circuit diagram showing an ASK modulator having a two-stage connection configuration according to Embodiment 3 of the present invention. In FIG. 3, the second embodiment shown in FIG.
The same parts as those described above are denoted by the same reference numerals, and description thereof will be omitted. As new codes, 11 and 12 are a capacitor connected between the carrier input terminal 1 and the modulated wave output terminal 3 for cutting off a DC component, and a resistor connected in series with the capacitor 11.

Next, the operation will be described. The capacitor 11 separates the carrier input terminal 1 and the modulated wave output terminal 3 in a DC manner. Part of the carrier input from the carrier input terminal 1 always leaks to the modulated wave output terminal 3 through the capacitor 11 and the resistor 12. The other operation of the modulation circuit is the same as that of the second embodiment, and the description is omitted.

That is, in the third embodiment, the carrier through the matching circuit is input to the first gate of the dual-gate FET, and the baseband signal is input to the second gate.
A that outputs the SK modulated wave from the drain, converts the impedance through a matching circuit, and outputs from the modulated wave output terminal
By making the SK modulator a multistage connection configuration, a part of the carrier of the first-stage ASK modulator is leaked to the output of the last-stage ASK modulator through the resistor 12, and the output signal level when the carrier of the dual-gate FET is cut off is made constant. , To obtain an ASK modulated wave having an appropriate modulation degree.

Therefore, according to the third embodiment, since a part of the carrier is always leaked to the modulated wave output terminal 3, even if the isolation is too high when the carrier is cut off due to the variation, the FET may be too high. In addition, the output signal level when the carrier is cut off can be made constant, and by setting the resistance value, an ASK modulated output having an appropriate modulation degree can be obtained without being too large.

Embodiment 4 FIG. 4 is a circuit diagram showing an ASK modulator having a two-stage connection configuration according to a fourth embodiment of the present invention. 4, the same components as those of the second embodiment shown in FIG. 2 are denoted by the same reference numerals, and the description thereof will be omitted. As new codes, 11 'and 12' are dual gate FEs.
A capacitor connected between the first gate 13 of T7 and the drain 19 of the dual-gate FET 8 for blocking a DC component, and a resistor connected in series to the capacitor.

Next, the operation will be described. A part of the carrier input from the carrier input terminal 1 and passing through the matching circuit 4 passes through the matching circuit 6 through the capacitor 11 'and the resistor 12'.
, And is always leaked to the modulated wave output terminal 3.

Therefore, according to the fourth embodiment, even if the connection position of the series connection of the capacitor 11 'and the resistor 12' is changed, a part of the carrier is always leaked to the output as in the third embodiment. Thus, it is possible to obtain an ASK modulated output having an appropriate modulation degree without being too large.

In the first to fourth embodiments, the AS
Although the case where the K modulation circuit is constituted by the dual gate FET has been described, the same effect can be obtained even if the two single gate FETs are constituted by the cascode connection.

[0028]

As described above, according to the present invention, the FE
By using an ASK modulation circuit that outputs an ASK modulated wave by controlling the carrier with a baseband signal using T, the ASK modulator is configured in a multi-stage configuration. There is an effect of obtaining an ASK modulated wave having a high modulation and a large modulation degree.

ASK is connected to each FET connected in multiple stages.
Providing the stabilization circuits for feeding the output of the modulated wave back to the gate to which the carrier is input allows the ASK modulation circuit to operate in a stable state.

Further, by providing a leakage means for constantly leaking a part of the input carrier to the output side, the passage loss at the time of carrier cut-off is kept constant, so that the isolation at the time of carrier cut-off due to the variation of FET is high. It is possible to prevent the modulation level from being excessively high, and it is possible to obtain an ASK modulated wave having an appropriate modulation level by keeping the output signal level constant when the carrier is cut off.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing an ASK modulator having a multi-stage connection configuration according to a first embodiment of the present invention.

FIG. 2 is a circuit diagram showing an ASK modulator having a multi-stage connection configuration according to a second embodiment of the present invention.

FIG. 3 is a circuit diagram showing an ASK modulator having a multistage connection configuration according to a third embodiment of the present invention.

FIG. 4 is a circuit diagram showing an ASK modulator having a multistage connection configuration according to a fourth embodiment of the present invention.

FIG. 5 is a circuit diagram showing a conventional ASK modulator.

[Explanation of symbols]

4 Matching circuit (input side), 5 stage matching circuit, 6 matching circuit (output side), 7 dual gate FET (first stage ASK
Modulation circuit), 8 dual-gate FET (second stage ASK)
Modulation circuit), 9 stabilization circuit (first-stage ASK modulation circuit),
10 stabilization circuit (second stage ASK modulation circuit), 11, 1
1 'Condenser constituting leakage means, 12, 12'
Resistance that constitutes a means of leakage.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Kenji Suematsu 2-3-2 Marunouchi, Chiyoda-ku, Tokyo Mitsui Electric Co., Ltd. (72) Inventor Nao Takagi 2-3-2 Marunouchi, Chiyoda-ku, Tokyo 3 Rishi Electric Co., Ltd. F-term (reference) 5K004 AA03 DA03 DD01 DE00

Claims (3)

[Claims] 1. An ASK modulator characterized in that an ASK modulation circuit using FETs has a multistage connection configuration. 2. The ASK modulator according to claim 1, wherein each of the FETs connected in multiple stages is provided with a stabilizing circuit for feeding back the output of the ASK modulated wave to a gate to which a carrier is input. ASK modulator. 3. The ASK modulator according to claim 1, further comprising: a leakage unit that constantly leaks a part of the input carrier to an output side.