JPS6238031A - Transmission output control circuit - Google Patents

Abstract

PURPOSE:To attain temperature compensation with high accuracy by cancelling the change in the detection output due to the temperature rise mainly of a power detection section and a control section by >=1 series connection temperature compensation diode. CONSTITUTION:Suppose that the temperature characteristic due to the change in the surrounding temperature rise of the power detection section 5 and the control section gives a change of +DELTAV to the detection output (e). The fluctua tion of the detected output (e) cue to the surrounding temperature rise is can celled by deciding number od diodes (d) constituting a diode D and resistors R1, R2 so as to make the temperature change in the temperature compensation diode D as -DELTAV against the change of +DELTAV, then the temperature compensa tion is attained. Thus, the voltage of the cathode of a Zener diode D2 is un changed, then a constant bias current is fed to the 1st transistor (TR)1 and no operating current change is arisen in the 1st and 2nd TRs 1, 2. Thus, a transmission output control circuit 81 of the control section 7 is not affected by the change in the temperature characteristic due to the rise in the ambient temperature.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to temperature compensation of a transmission output control circuit that keeps the transmission output of a transmitter constant.

[Conventional technology]

The transmission output control circuit is used, for example, in a transmitter of a very high frequency radiotelephone device, as shown in the block diagram of FIG.

This is used to keep the transmission output constant at all times by extracting a part of the transmission output and feeding it back to the previous stage.

That is, in FIG. 2, 1 is a transmitting section, 2 is a pre-stage section, 3 is an excitation section, 4 is a power amplification section, 5 is a power detection section, 6 is a low-pass filter, and 7 is a control section.

A predetermined frequency transmitted by the transmitting section 1 is subjected to necessary modulation, multiplication, mixing, etc. in the pre-stage section 2, and is amplified to the power necessary for the power amplifying section 4 in the excitation section 3.

The output of the power amplifying section 4 is sent to a terminal 8 via a power detecting section 5 and a low-pass filter 6 that removes harmonic components of the transmission output.
yoυ will be sent.

In this case, in order to output a predetermined transmission output from terminal 8,
The output of the power amplification section 4 is constantly detected by the power detection section 8, and the control section 7 controls the output of the power amplification section 4 to a predetermined value in accordance with this detected output.

Conventional transmission output control circuit 71 used in this control section 7
As shown in FIG. 3, a semi-fixed resistor 73 is connected between the input terminal 72 and the earth, and receives the detection output e detected by the power detection unit 5 and output from the output terminal 51. An output terminal 74 of the resistor 73 is connected via a resistor 75 to the base of the first transistor TR.

The collector of the first transistor TRI is connected to the collector power supply Vcc through a resistor 76, and the collector of the first transistor TRI is connected to the collector power supply Vcc through a resistor 76.
connected to the bases of R2 and the second transistor TR
The collector and emitter of No. 2 are connected to the collector power supply Vcc and the output terminal 77, respectively.

The transmission output control circuit 71 configured in this manner receives the detection output e detected by the power detection section 5 with the semi-fixed resistor 73, and amplifies it with the first transistor TRI and the second transistor TR2.

The output is sent from the output terminal 77 to the power amplifying section 4 at the input terminal 4.
1.

Thereby, the output of the stain force amplifying section 4 is controlled so that it always has a predetermined value.

Incidentally, the power detection section 5 has a detection output e that fluctuates due to changes in ambient temperature rise. This variation in the detection output e is mainly caused by the temperature characteristics of the diode (not shown) used in the power detection section 5, and the variation in the detection output e due to this temperature change is suppressed by the first transistor TR. Compensation is provided by a resistor 78 and a temperature compensation diode 79 connected in series between the base and the earth.

(Problems to be Solved by the Invention) However, such a conventional transmission output control circuit 71
In this case, the output characteristics change depending on the ambient temperature characteristics of the control circuit 71 itself. In particular, the rise characteristics of the first transistor TR change with changes in ambient temperature.

In this case, even if the temperature change in the power detection section 5 can be compensated for by the diode 79, there is a problem that temperature compensation for the control circuit 71 itself cannot be performed sufficiently because only the diode 79 can be connected.

Similarly, it is possible to use a thermistor (not shown) in place of the diode 79, but the temperature characteristics of the thermistor are
Since the temperature characteristics of the diode of the power detection section 5 and the temperature characteristics of the control circuit 71 themselves are different, there is a problem that appropriate temperature compensation cannot be performed.

An object of the present invention is to provide a transmission output control circuit that can solve the above-mentioned conventional problems.

(Means for Solving the Problems) A configuration for achieving the above object will be explained with reference to FIG. 1 corresponding to an embodiment.

The transmission output control circuit 81 according to the present invention used in the control unit 7 of the transmitter explained in FIG. 2 is the transmission output control circuit 71 explained in FIG.

A resistor 75 connected between the output terminal 74 of the semi-fixed resistor 73 and the base of the first transistor TR, a resistor 78 connected in series between the base ground of the first transistor TR, and the temperature In place of the compensating diode 79, a bias power supply (2) for the first transistor TRI is provided, and a Zener diode D is connected between this bias power supply (vb) and the ground.
7. a resistor RI+ whose cathode is connected in series with the resistor R, and whose anode is connected in series with the resistor R2; and a Zener diode D7. Resistance R
2, the other end of resistor R1 is connected to bias power supply Vb, and resistor R2
The other ends are connected to the ground, and the midpoint between the Zener diode D2 and the resistor R2 is connected to the first transistor TR.
I is connected to the base of the zener diode D, and the connection midpoint between the Zener diode D and the resistor R1 is connected to the output terminal 74 of the semi-fixed resistor 73.
Insert one or more temperature compensating diodes D in series so that their cathodes are connected to the output terminal 74. It has the same configuration as the circuit.

(For f, -) It is assumed that the temperature characteristics of the power detection unit 5 and the control unit 7 due to changes in ambient temperature rise give a change of +△V to the detection output C, and temperature compensation is performed for this +△V. The number of diodes d constituting the diode D and the values of the resistors R1*R2 are determined so that the temperature change of the diode D becomes 1△■.

This eliminates the variation in the detection output e due to the rise in ambient temperature, making temperature compensation possible.

Therefore, since the voltage on the cathode side of the Zener diode D2 does not change, a constant bias current is supplied to the first transistor TR1 and the second transistor T
There is no change in the operating currents of R1 and TR2.

Therefore, the transmission output control circuit 81 of the control section 7.

It is not affected by changes in temperature characteristics due to increases in ambient temperature.

(Example) The present invention will be explained below with reference to the drawings. FIG. 1 shows a circuit diagram of an embodiment according to the present invention, and the same parts as those in the conventional transmission output control circuit 71 shown in FIG. 3 are given the same reference numerals.

Section 9: The transmission output control circuit 81 according to the present invention.

As shown in FIG. 1, the resistor 75 in the conventional example shown in FIG.
．． 78 and the temperature compensation diode 79, a bias power supply vb is provided in the first transistor TRI, and a Zener diode D2 is provided between the bias power supply vb and the earth.
The cathode of the resistor R1 is connected in series with the resistor R2, and the anode thereof is connected in series with the resistor R2.A Zener diode D2. Resistance R2
The resistor R1 is connected to the bias power supply vb, the other end of the resistor R2 is connected to the ground, and the midpoint between the Zener diode D2 and the resistor R2 is connected to the base of the first transistor TR. One or more temperature compensation diodes D are inserted and connected in series between the output terminal 74 of the semi-fixed resistor 73 and the diodes D and L, such that the cathode of the component diode d is connected to the output terminal 74. Except for this, it has the same configuration as the conventional example shown in FIG.

Note that the Zener diode D2 is used to increase the voltage on the cathode side of the diode D, and the Zener voltage is mainly determined by the number of diodes d making up the diode D.

Transmission output control circuit 8 according to the present invention configured as described above
The operation of No. 1 will be explained next.

A detection output e from the output terminal 51 of the power detection section 5 is applied to the semi-fixed resistor 73 via the input terminal 72 of the control circuit 81, and a part of it is derived from the output terminal 74.

It is now assumed that the detection output e applied to the semi-fixed resistor 73 changes by 10V due to a change in temperature rise. +△V due to this temperature change is mainly caused by the power detection section 5 and the control section 7.
This is due to the temperature characteristics of the control circuit 81, and others.

The power amplifier and its inputs also change.

In order to cancel this +△V, the number of diodes d and the resistance R1*R are adjusted so that the temperature change of the diode D becomes 1∆V.
Determine the value of 2.

As a result, +△V due to temperature change is canceled out by 1△V.

Therefore, bias power supply vb! The bias current supplied to the first transistor TR by /c operates so that the output of the transmitting section remains constant even when the temperature of the power detecting section 5 and the control circuit 81 changes.

Therefore, the power detection unit 5. Even if the detection output eK changes due to the temperature characteristics of the control section 7, the change is canceled by the temperature compensation diode D, and the control output according to the multi-temperature characteristics is always sent from the output terminal 77 to the input terminal 41 of the power amplifier section 4. Sent from

(Effects of the Invention) As explained above, according to the present invention, the transmission output control circuit of the transmitting section of a very high frequency radio device mainly controls changes in detection output due to temperature rises in the power detection section and the control section by one or more detection outputs. By canceling the temperature compensation with a series-connected temperature compensation diode, highly accurate temperature compensation can be performed and stable operation can be guaranteed.

[Brief explanation of drawings]

Figure 1 is a circuit diagram of an embodiment of a transmission output control circuit according to the present invention, Figure 2 is a block diagram of a transmitter using the transmission output control circuit, and Figure 3 is a circuit diagram of a conventional transmission output control circuit. be. DESCRIPTION OF SYMBOLS 1... Oscillator part, 2... Pre-stage part, 3... Excitation part, 4...
... Power amplification section, 5... Power detection section, 6... Low pass filter, 7... Control section, 8... Terminal, 71.81.
... Transmission output control circuit, 73 ... Semi-fixed resistor, 74
...output terminal, TR, ...first transistor, TR2...second transistor, D, d, 79
... Temperature compensation diode y DZ ... Zener diode, Vb ... Bias power supply, vo. ...Collector supply power.

Claims (1)

[Claims] The detected output of the transmitter detected by the power detection section is applied to the base of the first transistor via a semi-fixed resistor, and the control output obtained by the second transistor is applied to the transmitter. In the transmission output control circuit that outputs the output to the power amplifying section of the transmitter and keeps the transmission output of the transmitter constant, a bias power source for the first transistor is provided, and a cathode of a Zener diode is connected between the bias power source and the earth. A first resistor whose anode is connected in series to the second resistor, a Zener diode, and a second resistor, the other end of the first resistor is connected to the bias power supply, and the second resistor is connected in series. The other ends are respectively connected to the ground, and the midpoint of connection between the Zener diode and the second resistor is connected to the first resistor.
is connected to the base of the transistor, and one or more temperature-compensating diodes are connected between the midpoint of the connection between the Zener diode and the first resistor and the output terminal of the semi-fixed resistor, so that their cathodes are connected to the output terminal of the semi-fixed resistor. A transmission output control circuit characterized by being inserted and connected in series so as to be connected to a terminal.