JPS59167B2 - Receiver tuning device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a channel selection device for a receiver, and more particularly to an electronic channel selection device for a radio receiver.

In recent receiving devices, variable capacitance diodes are used as tuning elements to enable preset channel selection and miniaturization of the device.

Since the control voltage applied to this variable capacitance diode is determined by the highest and lowest reception frequencies in the electronically tuned tuner, a high control voltage is required to sufficiently cover the required reception frequency band.

In receivers for automobiles and portaples, the set power supply voltage is kept below a certain value, so it is impossible to make the control voltage applied to the variable capacitance diode higher than the set power supply voltage.

Therefore, the following method has been adopted as a means for obtaining a control voltage sufficient to cover all the necessary reception frequency bands.

That is, a set power source (battery) is used as an operating power source for a voltage generating circuit that generates a control voltage, such as a tuning pulse generator, controller, D/A converter, etc.
The voltage is boosted by a C converter and the boosted output is stabilized by a high precision regulator.

This configuration has the disadvantage that the capacity of the DC-DC converter and regulator must be relatively large, resulting in a large-sized device.

SUMMARY OF THE INVENTION An object of the present invention is to provide a receiver channel selection device that is required to sufficiently increase the control voltage applied to the variable capacitance diode and can downsize the C-DC converter.

The present invention will be explained below with reference to the drawings.

The figure is a circuit block diagram showing one embodiment of the present invention.

An input signal IN from the antenna 1 is applied to an amplifier circuit 2 including an RF amplification section and an IF amplification section.

In this amplifier circuit 2, a variable capacitance diode 10 is used as a capacitive element constituting a tuning circuit, and a reception signal is selected by varying the reverse direction applied voltage Vf to this diode 10 in accordance with a channel selection operation. .

The IF output of the amplifier circuit 2 is power-amplified by the amplifier circuit 3 including a detection circuit and the like to drive the speaker 4.

The circuit configuration for generating the control voltage Vf applied to the variable capacitance diode 10 is as follows.

That is, a tuning pulse train signal is generated from the tuning pulse generation circuit 5 in conjunction with the operation of the tuning dial.

This pulse train is input to the controller 6, and the output pulse train of the controller 6 is converted into a DC voltage by an integrating circuit 7 serving as a DC voltage generation means (D/A conversion means) that generates a DC voltage corresponding to the number of pulses, and the application is controlled. Voltage Vf
becomes.

Further, the contents of a pulse counter (not shown) in the controller can be transferred to the memory 9 by pressing the preset button, and the contents of the memory can be read out to the counter by pressing the tuning button 8 to enable preset tuning.

These, controller 6, memory 9. A part of the tuning pulse generator 5 and the like are integrated into an integrated circuit (IC) 20 .

In the present invention, an integrating circuit 7 having an active element is used to D/A convert the tuning pulse train from the controller 6 and converting it into a DC voltage. This increases the output Vf.

Specifically, as shown in the figure, it is composed of an integrating circuit using an operational amplifier 11.

More specifically, a capacitive element C and a resistor R2 are connected in parallel to each other between the operational amplifier 11, its output, and its inverting input, and its inverting input is connected to an input resistor R1. A pulse train signal from the controller 6 is supplied via the resistor R1.

The non-inverting input of the operational amplifier 11 is grounded to form an inverting and integrating circuit T.

In such a configuration, the output voltage Vf of the integrator 7 - the output signal of the integrator 7 and the negative power supply voltage are sufficiently large and
If the gain of is sufficiently large, the gain as an integrator is R2
As a result, the output pulse signal (vi) of the controller 6 is converted by the integrator 7 into a control voltage Vf whose maximum value is a sufficiently large DC voltage.

For this purpose, the DC-DC converter 14 is used as the negative power supply voltage of the operational amplifier 11 of the integrator 7, and by boosting the set power supply element B, the negative voltage is made sufficiently large, and as a result, the integral output Vf is increased. are doing.

However, the set power supply element B can be used as is for the positive power supply of the operational amplifier.

In this way, since the output Vf of the integrator 7 can be made sufficiently large, the operating power supply of the IC circuit 20 including the controller 6 is strictly controlled by the high-precision regulator 15 without boosting the set voltage element B. It is sufficient to stabilize the output pulse signal and control the level of the output pulse signal to a constant value.

As stated above, if the boost voltage of the DC-DC converter 14 is sufficiently large, the gain of the integrator 7 depends only on R1 and is constant.
It can be seen that if the level of the output pulse signal is controlled to be constant, voltage accuracy of the converter 14 is not required, and a sufficiently high applied control voltage Vf can be obtained.

Therefore, since the integrator 7 is the only load in the DC-DC converter 14, its capacity is also smaller than in the conventional example, and further miniaturization can be achieved.

According to the present invention, since the capacity of the converter can be reduced, it is possible to downsize the device, and it is particularly effective in receivers for vehicles and portable use where the set power supply voltage is limited.

[Brief explanation of drawings]

The figure is a circuit block diagram showing one embodiment of the present invention. Explanation of symbols of main parts, 5...Tuning pulse generator, 6...Controller, 7...
...Integrator, 10...Variable capacitance diode, 1
1... operational amplifier, 14... DC-D
C converter, R1, R2...Resistance, C...
...Capacitive element.

Claims (1)

[Scope of Claims] 1. Signal generation means for generating a pulse signal in response to a channel selection operation; DC voltage generation means for generating a DC voltage corresponding to the pulse signal; A channel selection device for a receiver including a variable capacitance element whose capacitance value is controlled by a DC voltage, wherein the DC voltage generation means is composed of an integrating circuit using an active element, and the device power supply is used as an operating power source for the integrating circuit. A receiver channel selection device characterized by boosting and supplying. 2. The integrating circuit includes an operational amplifier, a capacitive element and a resistor connected in parallel between the input of the operational amplifier, and an input of the operational amplifier and the output of the signal generating means. 2. The receiver channel selection device according to claim 1, further comprising a connected input resistor.