JP3819965B2 - Transmission circuit and automatic transmission power adjustment method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a transmission circuit and a transmission power automatic adjustment method thereof, and more particularly to a transmission circuit using a varactor diode multiplier and a transmission power automatic adjustment method thereof.
[0002]
[Prior art]
FIG. 2 shows a conventional circuit of a transmission circuit in which an intermediate frequency signal is amplified and then converted to a transmission frequency by a multiplier using a varactor diode and transmitted. In the figure, an input intermediate frequency signal is amplified by a variable gain amplifier 1 and converted to a transmission frequency by a varactor diode multiplier 2. The multiplied high-frequency signal is input to the bandpass filter 4 via the isolator 3, where unnecessary waves are removed and transmitted.
[0003]
A part of the transmission high-frequency output is branched by the directional coupler 5, converted into a DC signal corresponding to the high-frequency output level by the detector 6, amplified by the DC amplifier 7 and applied to the control terminal of the variable gain amplifier 1, Form a feedback loop. This feedback loop operates as an automatic power adjustment circuit for keeping the output level of the transmitted high-frequency signal constant.
[0004]
[Problems to be solved by the invention]
In the conventional transmission circuit described above, a directional coupler, a detector, and a DC amplifier are required for automatic power adjustment, and the circuit is increased in size and complexity by that amount, resulting in high costs.
[0005]
SUMMARY OF THE INVENTION An object of the present invention is to provide a transmission circuit using a varactor diode multiplier, and a transmission circuit and a method for automatically adjusting the transmission power that can reduce the size and cost of the circuit configuration.
[0006]
[Means for Solving the Problems]
The present invention includes a variable gain amplifier for amplifying an intermediate frequency signal;
A multiplier for multiplying an output signal of the variable gain amplifier using a varactor diode and a self-bias resistor of the varactor diode to generate a high-frequency signal ;
A bandpass filter for generating a transmission high-frequency signal by removing unnecessary waves contained in the high-frequency signal output from the multiplier;
A direct-current amplifier for generating a control voltage for inverting and amplifying a self-bias voltage generated between both terminals of the self-bias resistor to control the gain of the variable gain amplifier;
A transmission circuit comprising:
[0007]
Furthermore, the present invention provides a transmission circuit configured to amplify an intermediate frequency signal by a variable gain amplifier, and then multiply and output by a multiplier using a varactor diode to which a self-bias resistor is connected in parallel. The transmission power automatic adjustment method of
The transmission power is controlled by inverting and amplifying a self-bias voltage generated between both terminals of the self-bias resistor of the varactor diode by a DC amplifier to control the gain of the variable gain amplifier. A method for automatically adjusting transmission power of a transmission circuit is disclosed.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below. FIG. 1 is a block diagram showing a configuration example of a transmission circuit according to the present invention. A variable gain amplifier 1, an isolator 3, and a band pass filter 4 are the same as those of the conventional circuit of FIG. The varactor diode multiplier 8 has the same configuration as the conventional one, but the self-bias voltage V generated between both terminals of the varactor diode 83 inside is taken out to the outside and is amplified by the DC amplifier 9 to be variable. A feature of the present embodiment is that it is used as a feedback control voltage to the gain amplifier 1.
[0009]
FIG. 3 shows an example of characteristics of the varactor diode multiplier 8. As the level of the intermediate frequency signal (IF) input through the matching circuit (MN) 81 increases, the level of the high-frequency output output through the matching circuit (MN) 82 also increases. The terminal voltage V of the self-bias resistor 84 of the varactor diode 83 generated in this manner decreases as the intermediate frequency signal level increases as shown in the lower part of FIG. Therefore, the voltage V can be used as an amount representing the output level, although the increase / decrease relationship with the output level of the high-frequency signal (RF) is opposite.
[0010]
The present invention makes use of the characteristics of the varactor diode multiplier and performs feedback control to the variable gain amplifier 1 by inverting and amplifying the terminal voltage V of the varactor diode 83, that is, the self-bias resistor 84 with the DC amplifier 9. Since automatic power adjustment is performed, a conventional directional coupler and detector are not required, and the circuit configuration can be reduced in size and cost.
[0011]
【The invention's effect】
According to the present invention, there is an effect that the transmission circuit using the varactor diode multiplier can be reduced in size, the number of parts can be reduced, and the cost can be reduced.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration example of a transmission circuit according to the present invention.
FIG. 2 is a block diagram illustrating a configuration example of a conventional transmission circuit.
FIG. 3 is a diagram illustrating a characteristic example of a varactor diode multiplier.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Variable gain amplifier 3 Isolator 4 Band pass filter 5 Directional coupler 6 Detector 7 DC amplifier 8 Varactor diode multiplier 9 DC amplifier 81 Matching circuit 82 Matching circuit 83 Varactor diode 84 Self-bias resistor

Claims (2)

A variable gain amplifier for amplifying the intermediate frequency signal;
A multiplier for multiplying an output signal of the variable gain amplifier using a varactor diode and a self-bias resistor of the varactor diode to generate a high-frequency signal ;
A bandpass filter for generating a transmission high-frequency signal by removing unnecessary waves contained in the high-frequency signal output from the multiplier;
A direct-current amplifier for generating a control voltage for inverting and amplifying a self-bias voltage generated between both terminals of the self-bias resistor to control the gain of the variable gain amplifier;
A transmission circuit comprising: Automatic adjustment of transmission power of a transmission circuit configured to amplify an intermediate frequency signal with a variable gain amplifier and then multiply and output by a multiplier using a varactor diode with a self-bias resistor connected in parallel A method,
The transmission power is controlled by inverting and amplifying a self-bias voltage generated between both terminals of the self-bias resistor of the varactor diode by a DC amplifier to control the gain of the variable gain amplifier. A method for automatically adjusting transmission power of a transmission circuit.

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