JPS5826689B2 - Chu-na-souchi - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a tuner device for a high frequency receiver, and aims to increase tuning accuracy and enable multi-channel reception.

Conventional tuner tuning methods can be roughly divided into two types: a method in which tuning is performed using a continuously variable reactance element, and a method in which tuning is performed by sequentially switching reactance elements having a constant value.

The major drawback of the former is the variation in the change characteristics of the actance element. For example, if a variable capacitor is used, it must be corrected by finely adjusting the spacing of the rotor section, and if a variable capacitance diode is used, the characteristics must be matched by selection and tuning. The disadvantage is that the frequency accuracy is low.

The latter has the disadvantage that it requires as many reactance elements with a fixed value as the number of reception channels, which complicates wiring and assembly, making it unsuitable for multi-channel reception.

FIG. 1 shows a conventional example of a tuning circuit in which the tuning frequency is changed by electronically switching a coil.

DB t D2 t D3 t D4 p D5 is a switching diode, C2t C3y C4t C5t
C6 is a bypass capacitor, R1, R2, R3, R4
, R5 are current limiting and high frequency signal blocking resistors, C1 is a direct current blocking capacitor, C7 is a resonant capacitor, El is a switching power supply, and SWl is a resonant frequency changeover switch.

A parallel resonant circuit is formed between terminals 1 and 2, and diodes D1 to D5 are connected depending on the switching position of changeover switch SW1.
For example, in the state shown in FIG. 1, the coil L6 is short-circuited, and the resonant frequency is determined by the inductance of the series-connected coils L1 to L5 and the capacitance of C7.

In FIG. 1, 6 types of resonant frequencies can be selected, but 12 types of switching frequencies are required in the case of television broadcast reception, and 28 types in total are required when considering the increase in cable television channels.

Therefore, if the circuit configuration is similar to that shown in FIG. 1, 27 switching diodes and 28 coils are required.

Also, the wiring from the channel selection switch to the resonant circuit is 28
This makes adjustment and assembly difficult.

In particular, the coil element portion occupies a large volume, making it difficult to downsize it.

In order to eliminate the drawbacks of the conventional example described above, the present invention uses a capacitor instead of the coil shown in Fig. 1 to switch the common plate body wave number.The capacitor can be easily incorporated into an integrated circuit and can be miniaturized. Become.

Examples of the present invention will be described below.

FIG. 2 shows a basic configuration example of a capacitor switching type.

As shown in Fig. 2, the resonance capacitor 3,4゜5.6,
7, 8 and switching diode 10゜11.12,1
A plurality of series circuits 3, 14, and 15 are connected in parallel, and a resonant coil 9 is further connected in parallel to the parallel circuits to form a parallel resonant circuit between the terminals 30 and 31.

Each connection point between the capacitors 3, 4, 5, 6, 7, 8 and the switching diodes 10, 11, 12, 13, 14, 15 is connected to a resistor 1 for current limiting and high frequency signal blocking.
6, 17, 18, 19, 20, 21 and bypass capacitors 22, 23, 24, 25, 26, 27 to each fixed contact of the changeover switch 28.

A movable contact of this changeover switch 2B is connected to one end of a DC power supply 29.

The other end of this DC power supply is connected to one end of diodes 10-15.

When the changeover switch 28 is in the position shown in FIG. 2, only the switching diode 10 is conductive, and the coil 9 and capacitor 3 form a resonant circuit.

In this configuration, unlike the case shown in Fig. 1, the coil is 1
Even if a large number of capacitors are required, integrated circuit technology makes it possible to combine them into compact hybrid or monolithic integrated capacitors.

Capacitors 3-8, diodes 10-15 and resistors 1
Blocks 6 to 20 can be integrated into an integrated circuit as shown in FIG.

This integrated circuit is shown in Figure 4 as a circuit consisting of one capacitor, one resistor, and one diode (a diode is used by shorting the base collector of a transistor), and multiple of these can be made on the same substrate. Goodbye, third
As shown in the figure, an N-type silicon epitaxial thin film 33° 34.35 is uniformly grown on a silicon P-type substrate 32, and an acceptor (for example, boron) is partially diffused thereon to create separation diffusion. The process is similar to the process of creating a normal monolithic transistor.

Reference numeral 36 indicates a resistance due to base diffusion, which corresponds to the resistance in FIG.

34, 37, and 38 constitute the transistor shown in FIG.

40 is a dielectric layer made of 5i02, and the N+ region 41 with a high impurity concentration and the thin film 35 form the capacitor shown in FIG.

Terminals a, b, and c are shown in FIGS. 3 and 4.

In the case of FIG. 2, each value of capacitors 3 to 8 corresponds to a receiving channel, and one of capacitors 3 to 8 is selected and used by changeover switch 28.

However, with such means, if there are many reception channels, the number of capacitors will also increase.

Therefore, in the present invention, three capacitors 42.43°44 and three switching diodes 4 are used as shown in FIG.
5, 46° 47 and three resistors 4B, 49.50 constitute a capacitor block, and the specified signals input to the eight input terminals of the encoder 51 cause the diodes 45° 46.
The 47 conduction combinations are made into 8 ways, and the capacitance value is switched into 8 ways.

In this way, in order to obtain N different capacitance values, it is sufficient to use hN capacitor switching diodes instead of N capacitors.

That is, in the case of N=128, 128 capacitances can be obtained with 7 capacitors since 2128=7.

However, the required capacity value cannot necessarily be efficiently approximated by binary capacity, so if the receiving bands are far apart, such as the high and low bands of the VIF band, as in TV reception, the In some cases, it is better to approximate by evolutionary capacity.

The minimum capacity unit of the binary capacity is determined by the greatest common divisor of each required capacity value.

In this case, a small capacitance value may be required, but the minimum capacitance value that can be achieved is about 1 pF with a single capacitor, so for the lower digits, capacitors with a value that is an integer multiple of the greatest common divisor are connected in series. or it is practical to cover it by an automatic frequency control circuit.

What is shown in FIG. 6 is the three capacitors 42 shown in FIG.
, 43, 44, diode 45, 46° 47, resistor 48
, 49, 50, and this embodiment will be described below.

In FIG. 6, 52a and 52b are antenna input terminals, and the terminal 52a is connected to the connection point of input tuning coils 53 and 54 connected in series.

A capacitor block 55 is connected in parallel with the input tuning coils 53 and 54.

56 is a high frequency amplifier circuit to which this capacitor block is connected.

57 is an interstage tuning coil, to which capacitor blocks 58 and 59 similar to 55 are connected.

60 is a mixing circuit and intermediate frequency amplification circuit to which a capacitor block 59 is connected, 61 is a local oscillation circuit, 62 is an oscillation tuning coil of this oscillation circuit 61, and 63 is a capacitor block.

64.65 are intermediate frequency output tuning coils, 66a, 66b
is the output terminal.

Each of the three input terminals of each capacitor block 55, 58, 59, 63 has its corresponding terminal connected in common.
It is led to the outside as a book terminal.

Capacitor blocks 55.5B, 59.63 are made as one integrated circuit element 67, and each capacitor block 5
Since the wire connecting 5.5B and 59.63 is also provided in the integrated circuit, many lead wires are not exposed to the outside.

One encoder 6 corresponding to 51 in FIG. 5 to control the capacitor blocks 55, 58, 59, 63.
8 is provided independently from the integrated circuit element 67, and the three output terminals of this encoder 68 are connected to the integrated circuit element 67.
is connected to the three input terminals provided on the encoder 6.
The eight input terminals of 8 are connected to each fixed contact of the changeover switch 69.

A movable terminal of this changeover switch 69 is connected to a DC power supply 70.

The encoder 68 performs octal/binary conversion so that a 3-bit output can be obtained for switching between 8 channels.

When the selector switch 69 is switched to set the desired channel, a binary signal is generated from the encoder 68, which controls the on/off of the switching diodes of each capacitor block 55.5B and 59°63 to use the required number of capacitors. You can select the desired channel.

In the above embodiment, the capacitors in the capacitor block are connected in parallel, but they may be connected in series and unnecessary capacitors may be shorted with diodes. Alternatively, the range of variable capacitance may be expanded by combining a series-parallel circuit of capacitors with a diode. You can also do that.

As described above, the present invention includes a plurality of capacitor blocks each having a plurality of input terminals including a plurality of capacitors and a plurality of diodes connected to the capacitors so that one or any plurality of these capacitors can be used in combination. A plurality of capacitor blocks are connected in parallel, and one integrated circuit element is provided in a plurality of sets of capacitor blocks whose connection points are used as input terminals of the integrated circuit, and the input terminals of the integrated circuit elements are controlled, and the plurality of capacitor blocks are simultaneously controlled. This is a tuner device in which an encoder is provided independently from the integrated circuit element, and a large number of capacitors, which are one of the tuning elements, are provided so that they can be switched, and moreover, a plurality of capacitors can be used in combination. Since the number of capacitors is small and can be integrated into an integrated circuit, the device can be made extremely compact.

Furthermore, since it is possible to control with an encoder independently provided outside, the number of input terminals of the integrated circuit can be reduced.

Furthermore, since no variable capacitance diode is used, the accuracy of channel selection is also good.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram of a conventional tuner, Fig. 2 is a circuit diagram of a basic circuit of a tuner device devised prior to the present invention, and Fig. 3 is a main part of an integrated circuit element used in the tuner device. 4 is a circuit diagram of the element shown in FIG. 3, FIG. 5 is a circuit diagram of a basic circuit of a tuner device according to an embodiment of the present invention, and FIG. 6 is a circuit diagram of the same tuner device. 42.43,44... Capacitor, 45,46
゜47...Diode, 4B, 49,50...
...Resistance, 51.68 ...Encoder, 5
5, 58, 59° 63... Capacitor block, 69... Changeover switch, 67... Integrated circuit element.

Claims (1)

[Claims] 1. A plurality of capacitor blocks each having a plurality of input terminals including a plurality of capacitors and a plurality of diodes connected to the capacitors are connected in parallel so that one or any plurality of these capacitors can be used in combination, A plurality of sets of capacitor blocks with one integrated circuit element having these connection points as input terminals of the integrated circuit are provided, and an encoder that controls the input terminal of the integrated circuit element and controls the plurality of capacitor blocks simultaneously is connected to the integrated circuit. A tuner device characterized in that it is provided independently of an element.