JPH1013274A - Receiver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a receiver which can secure a good NF by connecting the main body unit of the receiver to an antenna amplifier unit via a transmission line and correcting the loss component in the transmission line. SOLUTION: A receiver consists of an AAU(antenna amplifier unit) A, a main body unit B and a transmission line 2 which connects together the AAU A and the unit B. The AAU A includes a VGD(variable gain amplification dumping means) 1 and a GC(gain control signal separation means) 9. The VGD 1 consists of the variable gain amplifier 1b which has the gain according to the gain control signal level of the GC 9 and an amplifier 1a. The main unit B consists of a local transmission means 4, a mixer means 3 and GCS(gain control signal generation means) 7. Then the GCS 7 consists of a detector 7a which generates the control voltage according to the output of the means 3, an applying voltage generation circuit 7b which generates the voltage to be applied to the line 2, based on the control voltage, and a filter circuit 7c which prevents from affecting the high-frequency signals.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a receiver comprising an amplifier (commonly called an antenna amplifier) connected to the next stage of an antenna, a transmission line, and a main body receiving unit, and in particular, to an Auto Gain Control (hereinafter referred to as AGC) control thereof. The present invention relates to a loop configuration and a method for implementing the loop.

[0002]

2. Description of the Related Art FIG. 11 is a block diagram of a conventional receiver. In the figure, A is an antenna amplifier unit, B is a main unit, α is an antenna, β is a speaker, and 2 is a transmission line connecting the antenna amplifier unit A and the main unit B. 1a is an amplifier for amplifying the signal received by the antenna α, 1b is a variable gain amplifier having a gain according to the control voltage level input from the detector 7d, and 3 is a frequency according to the frequency oscillated from the local oscillation means 4. The mixing means 7a for performing the conversion is a detector for generating a control voltage corresponding to the signal level output from the mixing means 3, and inputs this control voltage to the variable gain amplifier 1b. That is, AG
The C control loop is formed by a loop of the variable gain amplifier 1b, the mixing means 3, the detector 7d, and the variable gain amplifier 1b.
10 is a constant voltage circuit, which is an antenna amplifier unit A
Is provided to supply power to the power supply. Reference numeral 7c denotes a filter circuit for applying a DC voltage to the signal line and the transmission line 2 without affecting a high-frequency signal input via the transmission line 2. Reference numeral 8 denotes a capacitor for removing a DC voltage component applied to a signal line and transmitting only an AC component. The DC voltage passes through the transmission line 2 and passes through the antenna amplifier unit A
And only the DC voltage is supplied as power to the amplifier 1a by the filter circuit 9a. 5 is a demodulation means, 6
Is an audio circuit, the demodulation means 5 performs predetermined demodulation processing on the received signal, the audio circuit 6 performs processing such as D / A conversion and amplification, and outputs sound from the speaker β.

In such a conventional receiver, when a strong radio wave is received by the antenna α, the input level of the amplifier 1a rises and the output level of the amplifier 1a rises. When the output level of the amplifier 1a increases, the input level of the variable gain amplifier 1b increases, and as a result, the output level of the variable gain amplifier 1b increases. Then, the input level of the mixing means 3 increases, and as a result, the output level of the mixing means 3 also increases. At this time, for example, if the control voltage generated by the detector 7d decreases and the gain of the variable gain amplifier 1b decreases as the control voltage decreases, the output level of the variable gain amplifier 1b can be suppressed to a substantially constant value. it can. Generally, the mixing means 3 generates intermodulation distortion due to excessive input.
By setting the output level at which the GC operation starts and the output level of the variable gain amplifier 1b becomes substantially constant to be lower than the input level of the mixing means 3 where the intermodulation distortion occurs, the generation of the intermodulation distortion is suppressed. be able to.

Here, the NF of a conventional receiver will be considered.
The gain (G1) of the amplifier 1a is 10 dB, and NF (NF1)
Is 1 dB, the gain (G2) of the transmission line 2 is -5 dB, and NF
(NF2) is -5 dB, and the gain (G
3) 10 dB, NF (NF3) 1 dB, mixing means 3
Gain (G4) is -5 dB and NF (NF4) is -5 dB
Then, amplifier 1a-transmission line 2-variable gain amplifier 1
b- The value of NF of the mixing means 3 is obtained by the following equation. The values in the above equations are all true values. According to the above equation, NF is 2.11 dB.

[0005]

By the way, when the amplifiers are connected in the order of the amplifier 1a, the transmission line 2, and the variable gain amplifier 1b as in the above-mentioned conventional receiver, the stage before the variable gain amplifier 1b having a gain is connected. However, there is a problem that a good NF cannot be obtained because the loss of the transmission line is connected to the transmission line.

The present invention has been made to solve the above-described problems, and a first object is to obtain a good NF receiver.

A second object of the present invention is to accurately adjust the output level of at least one of the variable gain amplifying / attenuating means, the transmission line, the mixing means, and a block from which an output signal proportional to the output signal level of the mixing means is obtained. It is intended to obtain a receiver that can be set easily.

[0008]

SUMMARY OF THE INVENTION A receiver according to the present invention is an antenna amplifier having an antenna and a variable gain attenuating means for amplifying or attenuating the high frequency signal by changing the gain of a high frequency signal received by the antenna. A unit, a mixing unit for mixing an input signal and a signal from a local oscillation unit, a main unit installed at a position apart from the antenna amplifier unit, and connecting the antenna amplifier unit to the main unit; A transmission line, wherein the main unit generates a gain control signal for changing a gain of the variable gain amplification / attenuation unit based on an output from the mixing unit and supplies the gain control signal to the transmission line. The control signal generating means extracts the component of the gain control signal from the transmission line to the antenna amplifier unit. Those having a gain control signal separating means for supplying to the variable gain amplifier attenuation means.

Further, in the above configuration, the gain control signal generating means changes the first voltage value, which is a constant voltage value independent of the input signal level from the mixing means, and the input voltage level from the mixing means. The gain control signal is generated based on the second voltage value.

In the above configuration, the first voltage value is made variable.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1 FIG. FIG. 1 is a block diagram of a receiver according to a first embodiment of the present invention. In the figure, A is an antenna amplifier unit, B is a main unit, α is an antenna, β is a speaker, and 2 is an antenna amplifier unit A. And a transmission line that connects the main unit B. 1a is an amplifier for amplifying a signal received by the antenna α, 1b is a variable gain amplifier having a gain according to the voltage level of the gain control signal input from the gain control signal separating means 9, and the amplifier 1a-variable gain amplifier 1b constitutes the variable gain amplification / attenuation means 1. 3 is a mixing means for mixing the input signal and the signal from the local oscillating means 4, and 7a is a detector for generating a control voltage according to the signal level output from the mixing means 3, for example, as shown in FIG. Transistors Q1, Q2
It is composed of Reference numeral 7b denotes an applied voltage generation circuit that calculates a constant voltage and a control voltage generated by the detector 7a to generate a voltage to be applied to the transmission line 2, and includes, for example, an operational amplifier OP and a transistor Q4 as shown in FIG. It is configured. Reference numeral 7c denotes a filter circuit that applies a DC voltage and a low-frequency signal to the signal line and the transmission line 2 without affecting a high-frequency signal input via the transmission line 2. The gain control signal generating means 7 is composed of the above 7a, 7b and 7c.

Reference numeral 8 denotes a capacitor which removes a DC voltage and a low frequency signal applied to a signal line and transmits only a high frequency signal. The DC voltage and the low frequency signal generated by the gain control signal generating means 7 are applied to the transmission line 2 and sent to the antenna amplifier unit A, and only the DC voltage and the low frequency signal are input to the gain control signal separating means 9. The gain control signal separating means 9 includes a filter circuit 9a and, for example, a constant voltage removing circuit 9b as shown in FIG. The filter circuit 9a extracts a power supply voltage component and a control voltage component from the high frequency signal component, the power supply voltage component, and the control voltage component passing through the transmission line 2, and inputs the extracted components to the constant voltage removal circuit 9b.
The constant voltage removing circuit 9b removes a constant voltage from the power supply voltage component and the control voltage component, and generates a control voltage for controlling the gain of the variable gain amplifier 1b.

Reference numeral 5 denotes a demodulation unit, and 6 denotes an audio circuit. The demodulation unit 5 performs a predetermined demodulation process.
Performs predetermined audio processing. For example, Digita
1 Audio Broadcasting (hereinafter DAB
2 is shown in FIG. The demodulation means 5 includes a tuning amplification / mixing circuit 51, a quadrature demodulation means 52,
It is composed of an FT differential demodulation unit 53, a Viterbi decoding unit 54, an audio decoding unit 55, a synchronization control unit 56, and a system control unit 57, and performs processing such as demodulation. The audio circuit 6 includes a D / A converter 61 and an amplifier 62,
D / A conversion and amplification are performed. In the demodulation means 5, synchronization control is performed by the synchronization control means 56, and the system control means 5
At 7, the overall control is performed. By performing these processes, a sound is output from the speaker β.

In this receiver, as shown in FIG. 9, for example, the antenna α is installed at the upper part of the trunk of the passenger car, the antenna unit A is installed inside the trunk, and the main unit B is installed at the lower part of the front panel separated from the antenna unit A.
Transmission line 2 between antenna unit A and main unit B
Connected with.

In the receiver configured as described above, when a strong radio wave is received by the antenna α, the input signal level of the variable gain amplification / attenuation means 1 increases, and the variable gain amplification / attenuation composed of the amplifier 1a and the variable gain amplifier 1b. The output signal level of the means 1 increases. Variable gain amplification / attenuation means 1
Rises, the input signal level of the mixing means 3 rises. As a result, the output signal level of the mixing means 3 also rises and is input to the gain control signal generation means 7. FIG.
7a, the block 1 amplifies the input signal to a predetermined output level. Next, it is assumed that a signal as shown in FIG. Va-Vbe is output as the potential Vb of the emitter of the transistor Q2 as a result of applying Va to the base of the transistor Q2. When the input signal rises, Va-Vbe> Vb is satisfied, so that an emitter follower is formed by the transistor Q2 and the resistor Ra, and the capacitor Ca is charged. On the other hand, when the input signal falls, the fall of Vb is delayed by the action of the charged capacitor Ca, so that Va−Vbe <Vb, and the transistor Q
2 cuts off. As a result, the electric charge of the capacitor Ca cannot be discharged except through the resistor Ra, and the output signal of the block 2 becomes a signal as shown in FIG. 4B. Where resistance R
The current flowing to the b side is assumed to be negligible. After that, the block 3 is flattened by a low-pass filter including the resistor Rb and the capacitor Cb as shown in FIG. 4C. As a result, a DC voltage proportional to the signal level is obtained in the detector 7a, and this signal is used as a control voltage for controlling the gain of the variable gain amplifier 1b.

The applied voltage generation circuit 7b shown in FIG. 5 calculates a constant voltage for operating the antenna amplifier unit A and the control voltage to generate a voltage to be applied to the transmission line 2. In this circuit, a control voltage is input to an inverting input, and a constant voltage is input to a non-inverting input. In FIG. 5, assuming that the constant voltage is V1 and the control voltage is V2, the output voltage V0 becomes a gain control signal and can be expressed by the following equation.

In this equation, the first item is a constant voltage, and the second item is a voltage proportional to the control voltage. The filter circuit 7c transmits the gain control signal V0 to the transmission line 2 without affecting the high-frequency signal passing through the transmission line 2.
It is used to apply The gain control signal V0 passes through the transmission line 2 and is input to the gain control signal separating means 9. The gain control signal separating means 9 comprises a filter circuit 9a and a constant voltage removing circuit 9b. The filter circuit 9a separates only the gain control signal V0 from the transmission line without affecting the high frequency signal passing through the transmission line 2. 2
Used to extract from

The constant voltage removing circuit 9b shown in FIG.
In order to adapt to the input voltage range of the control signal of the variable gain amplifier 1b, a voltage V00 is generated by subtracting a constant voltage from the gain control signal V0 by the action of the constant voltage diode D1. By feeding back the control signal V00 to the variable gain amplifier 1b, the variable gain
To control the gain. FIG. 6 shows a dual gate FET circuit as an example of the variable gain amplifier 1b. A high frequency signal is applied to one G1 of the dual gate FET Q3,
When the control voltage is input to the FET, when the control voltage decreases, the drain current of the FET decreases, and the gain decreases. With this configuration, the variable gain amplifier 1b-transmission line 2-mixing means 3-detector 7a-applied voltage generation circuit 7b-filter circuit 7c-transmission line 2-filter circuit 9a-constant voltage removal circuit 9b-variable An AGC loop can be formed by the system of the gain amplifier 1b, and an almost constant output level can be obtained regardless of the level of the input signal level. Generally, the mixing means 3 generates an intermodulation distortion due to excessive input. However, when the AGC operation is started, the output level at which the output level of the variable gain amplifier 1b becomes substantially constant is determined by the mixing means 3 which generates the intermodulation distortion. , The occurrence of intermodulation distortion can be suppressed.

The NF of the first embodiment will be specifically calculated.
The gain (G1) of the amplifier 1a is 10 dB, and NF (NF1)
Is 1 dB, the gain (G2) of the transmission line is -5 dB, and NF
(NF2) is -5 dB, and the gain (G
3) 10 dB, NF (NF3) 1 dB, mixing means 3
Gain (G4) is -5 dB and NF (NF4) is -5 dB
If they are the same as in the conventional example, the NF of the amplifier 1a-variable gain amplifier 1b-transmission line 2-mixing means 3 can be obtained by the following formula. The values in the above equations are all true values. Applying the above equation gives N
F becomes 1.38 dB. That is, as in the conventional configuration,
The amplifier 1a and the variable gain amplifier 1b are separated from each other, and the variable gain amplifier 1b and the variable gain amplifier 1b are provided before the transmission line 2 as in the first embodiment. It can be seen that better NF can be obtained by disposing the attenuating means 1 and distributing the gain in a concentrated manner to the front stage of the transmission line 2.

Embodiment 2 FIG. 8 shows an applied voltage generation circuit 7.
In FIG. 5, which is an example of b, two fixed resistors used to apply a constant voltage to the non-inverting input terminal of the operational amplifier OP are replaced with variable resistors so that the voltage value can be changed. Is the same as that of FIG. With such a configuration, the variable gain amplification and attenuation means 1 corresponding to a predetermined input level by changing the variable resistance value,
The output level of a desired circuit block in the receiver such as the transmission line 2 and the mixing means 3 can be easily and accurately adjusted. Similar effects can be obtained by adjusting the input level at which the AGC starts to take effect as an adjustment method.

In the first and second embodiments, the applied voltage generating circuit has been described as a circuit using an operational amplifier. However, it can be configured using an applied voltage generating circuit without using an operational amplifier. Not even.

In the first and second embodiments, the amplifier 1a-variable gain amplifier 1b has been described as the variable gain attenuating means 1. However, the variable gain amplifier 1b
-It can be said that the configuration can be made in the order of the amplifiers 1a, or by connecting a plurality of variable gain amplifiers, or by connecting a plurality of amplifiers 1a with a variable attenuator using a PIN diode D2 as shown in FIG. Not even.

Although not specifically described in the above description, the gain control signal V0 extracted by the filter circuit 9a is used.
Can be used as a power source for the variable gain amplification and attenuating means 1 in addition to being used to generate the control signal V00 in the constant voltage removing circuit 9b. After the conversion, it is needless to say that it can be used for the power supply of the variable gain amplification / attenuation means 1.

[0024]

According to the present invention, as described above, since the variable gain amplifier or the amplifier is arranged before the transmission line, a better NF can be obtained as compared with the conventional example. Also,
The number of amplifiers required to obtain an NF equivalent to the conventional example can be reduced.

Also, an input signal generated due to a signal level error generated in a variable gain amplifier, a variable attenuator, a mixing means, a local oscillation means, a detector, an applied voltage generation circuit, a filter circuit, etc. and a difference in transmission line length. Can be adjusted by one variable resistor.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a receiver according to Embodiment 1 of the present invention.

FIG. 2 is a block diagram showing a demodulating unit and an audio circuit according to the first embodiment of the present invention.

FIG. 3 is a circuit diagram showing a detector according to the first embodiment of the present invention.

FIG. 4 is a waveform chart for explaining an operation of the detector according to the first embodiment of the present invention.

FIG. 5 is a circuit diagram showing an applied voltage generation circuit according to the first embodiment of the present invention.

FIG. 6 is a circuit diagram showing a variable gain amplifier according to Embodiment 1 of the present invention.

FIG. 7 is a circuit diagram showing a constant voltage removing unit according to the first embodiment of the present invention.

FIG. 8 is a circuit diagram showing an applied voltage generation circuit according to a second embodiment of the present invention.

FIG. 9 is a diagram illustrating an installation state of a general receiver.

FIG. 10 is a circuit diagram showing another variable attenuator used in the present invention.

FIG. 11 is a block diagram showing a conventional receiver.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 variable gain amplification / attenuation means, 1a amplifier, 1b variable gain amplifier, 2 transmission line, 3 mixing means, 4 local oscillation means, 5 demodulation means, 51 tuning amplification / mixing circuit, 52
Orthogonal demodulation means, 53 FFT differential demodulation means, 54 Viterbi decoding means, 55 audio decoding means, 56 synchronization control means, 57 system control means, 6 audio circuit, 61 D / A converter, 62 amplifier, 7 gain control signal generation Means, 7a detector, 7b applied voltage generation circuit, 7c filter circuit, 7d detector, 8 capacitor, 9 gain control signal separation means, 9a filter circuit, 9b constant voltage removing circuit, 10 constant voltage circuit, A antenna amplifier unit, B body unit, α antenna, β speaker, Q1, Q2, Q4 transistor, Q3 FET, D1 constant voltage diode, D2 P
IN diode, OP operational amplifier, Ra, Rb, R
1, R2, R3 resistors, Ca, Cb capacitors.

Claims (3)

[Claims] 1. An antenna, an antenna amplifier unit having variable gain amplification / attenuation means for changing the gain of a high frequency signal received by the antenna to amplify or attenuate the high frequency signal, an input signal and a signal from a local oscillation means. A mixing unit for mixing a signal and a main unit disposed at a position distant from the antenna amplifier unit, and a receiver including a transmission line connecting the antenna amplifier unit and the main unit; The unit includes a gain control signal generating means for generating a gain control signal for changing the gain of the variable gain amplifying and attenuating means based on an output from the mixing means and supplying the gain control signal to the transmission line. The unit extracts the component of the gain control signal from the transmission line and supplies the gain control signal to the variable gain amplification / attenuation means. A receiver comprising control signal separation means. 2. The gain control signal generating means includes: a first voltage value that is a constant voltage value that does not depend on an input signal level from the mixing means; and a second voltage value that changes depending on an input signal level from the mixing means. 2. The receiver according to claim 1, wherein the gain control signal is generated based on the voltage value. 3. The receiver according to claim 2, wherein the first voltage value is variable.