JPS6325799Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a booster, and particularly relates to a television antenna terminal (hereinafter simply referred to as TV), a video tape recorder (hereinafter simply referred to as VTR), and a TV booster.
Connected between the antenna and the TV receiver, and supplies the TV signal from the antenna to the TV receiver and VTR, respectively.
Regarding the booster that supplies the reproduced signal from However, in a booster having second and third amplifiers in the UHF band signal transmission path, the first and third amplifiers are connected in series between the power supply and ground, and the second amplifier is connected to the power supply. The purpose of this is to reduce the current consumption of the booster and reduce intermodulation distortion by connecting it between the booster and the ground and supplying power to each amplifier.

FIG. 1 shows a circuit block diagram of a conventional booster. A is a TV antenna, and among the signals that enter this antenna, the VTR band signal passes through a low-pass filter 1, and the FM signal band is attenuated by an FM trap 2.
It is supplied to the amplifier 3. Then, the signal is distributed to low-pass filters 5 and 6 by a distributor 4,
The signals that have passed through it are supplied to the VTR 9 and TV receiver 10 via terminals 7 and 8, respectively. These signal paths constitute a VHF band signal transmission path.

On the other hand, UHF of the TV signal entering the TV antenna
The band signal passes through a high-pass filter 11, is amplified by an amplifier 12, and then is supplied to a distributor 13. This distributor 13 distributes the signal to a high-pass filter 14 and an attenuator 15 . The signal that has passed through the high-pass filter 14 is sent to the VTR via terminal 7.
9. The signal attenuated by the attenuator 15 is amplified by the amplifier 16, passes through the mixer 17, and is supplied to the TV receiver 10 via the terminal 8. These signal paths constitute a UHF band signal transmission path.

The VHF band playback signal from the VTR 9 is sent to the mixer 17
is supplied to the TV receiver 10 via the terminal 8, similar to the TV signal described above, and is sent to the VTR 9.
The regenerated signal is received and reproduced by the TV receiver 10.

The reason why the amplifiers are connected in two stages 12 and 16 in the above UHF band signal path is because the VTR9
This is to increase isolation in order to prevent leakage of the reproduced signal from the antenna to the TV antenna A.

Operating power is supplied to the amplifiers 3, 12 and 16 as follows. Amplifier 3 is the power terminal
Although connected between Vcc and ground, amplifier 1
2 and 16 are connected in series between the power supply terminal Vcc and the ground, and power is supplied to each of them.

In this way, the reason why the amplifiers 12 and 16 are connected in series to the power supply and the power is supplied is because the current flowing through the amplifiers 12 and 16 is common.
This is because the current consumed by this booster can be reduced.

The conventional example described above has the following problems.
In other words, the amplifiers 12 and 16 in the UHF band signal path are connected in series with the power supply, and the power supply voltage applied to them is halved, so the power supplied to these amplifier transistors is halved. It's going to happen. Due to the nonlinear characteristics of the amplifier transistor (not shown), the UHF
Nonlinear distortion occurs between each input signal frequency of the band, and intermodulation distortion occurs in the amplified output.
In this case, third-order intermodulation distortion is especially large, which poses a problem.

FIG. 2 shows a graph showing the state of occurrence of intermodulation interference depending on the magnitude of power supplied to the transistor. As can be seen from this figure, intermodulation distortion increases as the supplied power decreases. It is also shown that distortion increases if the supplied power is too large. This means that when the collector current Ic is increased in order to increase the supplied power, the hFE-Ic characteristic of the transistor shows that when Ic is increased, hFE
This is because it reaches a non-linear part where the curve starts to decrease.

Intermodulation distortion occurs in both amplifiers 12 and 16, but since the distortion generated in amplifier 12 is amplified by amplifier 16, there is a problem in that the distortion is further worsened. Including intermodulation distortion generated in this way.
When a TV signal is received by a TV receiver, it appears as a striped pattern on the screen.

Furthermore, this means that when a VTR signal is played back on a TV, this distortion component will appear on the receiving screen.

The present invention solves the above problems, and one embodiment thereof will be described below with reference to the drawings. The feature of the present invention is that the current consumed by the booster is kept low and intermodulation distortion is reduced.

FIG. 3 shows a circuit block diagram of a booster according to an embodiment of the present invention. Components that are the same as those in FIG. 1 are designated by the same reference numerals, and their explanations will be omitted. The differences from the conventional example shown in FIG. 1 will be explained. Amplifier 12 is connected between power supply terminal Vcc and ground, and amplifiers 3 and 16 are connected in series and connected between power supply terminal Vcc and ground, and power is supplied to each amplifier.

Figure 4 shows amplifiers 3, 12 and 1 shown in Figure 3.
A specific circuit diagram of only 6 is shown. The same parts as in FIG. 3 are designated by the same reference numerals, and their explanation will be omitted.
_Q1 ~ _Q3 are transistors, R1 _{~ R18} are resistors, C1 _~
C ₁₈ represents a capacitor, and L ₁ to L ₅ represent coils, respectively. 3, 12 and 16 within the dotted lines correspond to the amplifiers 3, 12 and 16 shown in FIG. 3, respectively. First, power is supplied to the amplifier 13 by connecting the power terminal Vcc to the collector of the transistor _Q2 via the coil _L3 , and to the ground via the emitter and resistor _R9 . Furthermore, the bias voltage to the base is that the voltage at the midpoint of coil L ₃ is the voltage at the midpoint of resistor R ₆ R ₇ and resistor R ₈
It is supplied at partial pressure.

On the other hand, the supply of power to the amplifiers 3 and 16 will be described. The voltage at the power supply terminal Vcc is applied to the collector of the transistor Q ₃ through the parallel circuit of the coil L ₅ and the resistor R ₁₁ , and further to its emitter and the resistor.
It is fed to the amplifier 3 via _R16 . The bias voltage of this transistor is supplied to its base by dividing the voltage between the collector and the lower end of resistor R ₁₆ by resistors R ₁₂ , R ₁₃ and resistor R ₁₅ . The voltage appearing at the lower end of the resistor R ₁₆ is applied to the coil L ₂ of the amplifier circuit 3,
Transistor collector-emitter and resistance
Applied to the series connection of R ₅ . Its base bias voltage is the resistor voltage between coil L ₂ and ground.
The voltage is divided and supplied by R ₁ , R ₂ and resistor R ₃ . From these descriptions, it can be seen that the amplifiers 3 and 16 are connected in series between the power supply terminal Vcc and ground. Therefore, a common current (especially collector current) of the same magnitude flows through both amplifiers. Therefore, the amplifier 3
Since the current is shared between the booster and the booster 16, the booster current can be reduced accordingly.
This current is approximately the same as the current flowing through the amplifier 12.

On the other hand, the voltage applied to each amplifier is
The power supply voltage is applied as is to the amplifiers 3 and 16, but since they are connected in series, approximately half of the power supply voltage is applied to each of the amplifiers 3 and 16. . Therefore, the power supplied to amplifiers 3 and 16 is approximately half that of amplifier 12.

To explain the intermodulation distortion of each amplifier when power is supplied with such a configuration, the power of the amplifier 12 is selected in the part where the intermodulation distortion is small as shown in FIG. Intermodulation distortion is kept small. On the other hand, since the voltage applied between the collector and emitter of amplifiers 3 and 16 is halved, the intermodulation distortion in those amplifiers is
This will be greater than for the amplifier 12. However, since the amplifier 3 is in the VHF band signal path, and it is the only one in that signal path, this is not so much of a problem. On the other hand, the amplifier 16 in the UHF band signal path also has more distortion than the amplifier 12, but this amplifier 16 is the latter stage of the signal path, and the intermodulation distortion of the amplifier 12 in the first stage is Since it is small, even if some distortion occurs in the amplifier 16, it does not cause much of a problem. The intermodulation distortion of the booster according to the above embodiment is improved by about 3 dB in terms of input compared to the conventional booster. In addition, better results were obtained when the voltage applied to the amplifier 16 was made slightly larger than 3.

As explained above, the booster of the present invention does not have a configuration in which two amplifiers in the UHF band signal path are connected in series and power is supplied to them as in the conventional example, but an amplifier in the VHF signal path and an amplifier in the UHF signal path. Amplifier is connected in series with the power supply, and further UHF
Since the power supply voltage is directly applied to the amplifier at the first stage of the band signal path, the current consumption of the booster can be reduced, and intermodulation distortion can be kept low.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a conventional booster, FIG. 2 is a graph showing the state in which intermodulation distortion occurs with respect to the collector current of a transistor, FIG. 3 is a block diagram of a booster according to an embodiment of the present invention, and FIG. Each figure shows a specific circuit diagram of the amplifier shown in FIG. 3. 3, 12, 16...Amplifier, 9...Video tape recorder (VTR), 10...Television receiver (TV receiver), Vcc...Power terminal, Q ₁ to Q ₃ ...
...transistor.

Claims (1)

[Scope of utility model registration request] A first low-pass filter, a first amplifier, a first distributor, and a second low-pass filter are connected between the antenna terminal and the output terminal to the video tape recorder, and the first distributor and the television are connected. A VHF band signal path in which a third low-pass filter is connected between the output terminal to the television receiver, and a first high-pass filter and a third low-pass filter connected between the antenna terminal and the output terminal to the video tape recorder. 2 amplifiers,
A UHF device comprising a second distributor and a second high-pass filter connected, and a third amplifier and mixer connected between the second distributor and the output terminal to the television receiver. by connecting the first and third amplifiers in series between the power supply and the ground, and connecting the second amplifier between the power supply and the ground in the booster having a band signal path. A booster characterized in that power is supplied to each amplifier.