JPS61201514A - Tuning circuit device - Google Patents

Abstract

PURPOSE:To prevent unstable operation and abnormal oscillation by selecting the circuit constitution so that no interference current is caused between tuning circuits. CONSTITUTION:A resonance current I1 of a tuning circuit 1 flows a loop comprising elements L1, D1, C1 and a resonance current I2 of a tuning circuit 2 flows a loop of elements L2, D2, C2 and the current I1 does not flow the capacitor C2 or the current I2 does not flow the capacitor C1. Thus, even if the capacitors C1, C2 have more or less resistive component, no interference is caused between the tuning circuits 1 and 2. Thus, no abnormal oscillation is caused and no unstable operation takes place.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] This invention relates to a tuning/circuit device using a variable capacitance diode.

[Summary of the invention]

According to the present invention, when a plurality of variable capacitance diodes integrated into one chip are used in a plurality of tuned circuits in a radio receiver, etc., interference between the plurality of tuned circuits can be prevented by establishing a special connection between them. It is designed to prevent this. [Prior art] In a superheterodyne receiver, its tuning circuit (
When a varicap (variable capacitance diode) is used as a tuning element in a resonant circuit, the configuration is generally as shown in FIG.

That is, in the figure, an antenna tuning circuit (1) is constituted by a bar antenna coil Ll, a varicap D1, and a bypass capacitor C1, and its tuning output is supplied to a mixer circuit (3), and a coil L2 and a bypass capacitor C1 constitute an antenna tuning circuit (1). , the varicap D2, and the bypass capacitor C2 constitute a resonant circuit (2) of the local oscillation circuit (4), and the local oscillation signal is supplied to the mixer circuit (3). At this time, the varicap Dl is connected to the variable bias power supply (5) through the decoupling resistors R1 and R2.
, D2 are supplied with a channel selection voltage (control voltage) Vc to control the capacitances of the varicaps Dl and D2, thereby changing the reception frequency.

Further, in an autodyne receiver (straight receiver) or a superheterodyne receiver having a high frequency amplifier at the input stage, the input stage is configured as shown in FIG. 4, for example.

That is, in the same figure, the antenna tuning circuit (1) is configured by elements L+, Dl, and Cs, and the element L
2, D2, and 'C2 constitute a crotch tuning circuit (2), and the tuning output of the tuning circuit (11) is connected to a high frequency amplifier (
6) to the tuning circuit (2), where it is further selected and taken out. At this time, the channel selection voltage Vc is applied to the varicap D1. It is supplied to D2.

In this way, when there are multiple tuned circuits (11, +21), the tuned circuit (1) is created by bypass capacitors C1, C2 and decoupling resistors R1, R2 as described above.
It is necessary to separate (2) and (2) in terms of high frequency to prevent mutual interference.

[Problem that the invention seeks to solve]

By the way, as shown in FIG. 5 as a varicap, a plurality of varicaps, for example two varicaps D1. A composite varicap D12 is manufactured in which the anode electrodes are taken out independently as terminals A1 + A2 while the cathode electrodes are taken out in common as terminals. According to such a composite varicap D12, the varicap D1. Since the varicaps D2 are formed adjacent to each other, the characteristics of the varicaps Dx and D2 can be made the same, and there is no need to select or rank separate varicaps for use as in the past. It also has the advantage of lower manufacturing costs.

However, when this composite varicap D12 is used in the tuning circuits (1) and (2) of FIG. 3 or 4, troubles occur. In other words, this composite varicap D! 2 to the tuning circuit (1
), +21, bypass capacitor C3 and decoupling resistor R3 as shown in FIG.
will be sustained. In this case, as a matter of course, in the composite varicap D12, the impedance when looking at the terminal K from the cathode electrodes of the varicaps Di and D2 is made sufficiently small, so that the impedance between the varicaps D1 and D2 is sufficiently small. There is no interference between them.

However, in the connection shown in Fig. 6, the tuning circuit (1)
The resonant current 11 flows through the capacitor c3, and the resonant current 2 of the tuned circuit (2) also flows through the capacitor c3, so if there is impedance in the capacitor C3, there will be interference between the tuned circuits (1) and (2). Therefore, the impedance of capacitor C3 must be sufficiently small, and for this purpose, the capacitance of capacitor C3 must be sufficiently large and the equivalent series resistance must be sufficiently small. When the waveband is low, it is difficult to completely satisfy such conditions, and as a result, interference occurs between the tuned circuit (11 and (2)), causing abnormal oscillation, Operation may become unstable.

This invention attempts to solve these problems.

[Means for solving problems]

Therefore, in this invention, the tuning circuit (1).

(2) is configured as shown in FIG. 1 or 2, for example.

[Effect]

The resonant current ■1 of the tuned circuit (1) is the element s, ,
Dl.

The resonant current ■2 of the tuned circuit (2) flowing through the loop of element L2.C1 flows through the loop of element L2. D2. The current I flows through the loop of C2, and the current I does not flow through the capacitor C2, and the current II does not flow through the capacitor C1. Therefore, even if there is some impedance in capacitors C1 and C2, the tuning circuits (1) and (2)
Therefore, there is no possibility of abnormal oscillation or unstable operation.

Furthermore, the configuration for this purpose is extremely simple.

〔Example〕

That is, in the example shown in FIG. 1, a bar antenna coil L1 and a decal ring resistor R1 are connected in series between the anode terminal A1 of the composite varicap 012 and the ground, and the element LL.

A bypass capacitor C1 is connected between the connection midpoint of R1 and the cathode terminal of the composite varicap Dx2 to form an antenna tuning circuit (1).

In addition, a local oscillator coil or crotch coil L2 is connected between the anode terminal A2 of the composite varicap D12 and the ground, and a bypass capacitor C2 is connected between the cathode terminal and the ground, and the τ local oscillator circuit A resonant circuit or crotch tuning circuit (2) is constructed.

Further, a channel selection voltage (control voltage) Vc from a variable bias power supply (5) is supplied to the cathode terminal K through a decoupling resistor R3.

According to such a configuration, since the coil L1 and the variable resistor D1 are connected in parallel through the capacitor C1, these elements L1. Dt acts as a tuned circuit (11). Also, since the coil L2 and varicap D2 are connected in parallel through the capacitor C2, these elements L2 and D2 act as a tuned circuit (2).

At this time, the channel selection voltage Vc is supplied to the varicap D1 through the loop of power supply (5) → resistor R3 → varicap D1 - coil L1 → resistor R1 - power supply (5), and the power supply (5) →Resistor R3-Varicap D2→
A channel selection voltage Vc is supplied to the varicap D2 through a loop from the coil L2 to the power source (5).

Therefore, the tuning frequencies of the tuning circuits (1) and (21) change in conjunction with the tuning voltage Vc.

In this case, the resonant current 11 of the tuned circuit (1) is
The resonant current (2) of the tuned circuit (2) flows through the loop of elements LL, Dt, and C1 (7), and the resonant current (2) of the tuned circuit (2) flows through the loop of elements L2, Dt, and C1. D2. The current 11 does not flow through the capacitor C2 and the current I2 does not flow through the capacitor C1. Therefore,
Even if there is some impedance in the capacitors CL, C2, there will be no interference between the tuned circuits (1) and (2), and therefore abnormal oscillation or unstable operation will not occur. There is no.

Furthermore, the configuration for this purpose is extremely simple.

In the example shown in FIG. 2, the element L 21 D 2 +
C2 and R2 are connected in the same way as elements Lt, Dt, Ct, and R1 to form a tuning circuit (2), and a bypass capacitor C3 is connected between the cathode terminal and ground.
is connected.

According to such a configuration, the coil L1 and the varicap D
1 through the capacitor C1, these elements L1. D1 acts as a tuned circuit (1). Also, since the coil L2 and the varicap D2 are connected in parallel through the capacitor C2, these elements L
2. D2 acts as a tuned circuit (2).

At this time, the channel selection voltage Vc is supplied to the varicap D1 through the loop of power supply (5) → resistor R3 → varicap D1 - coil L1 - resistor R1 - power supply (5), and the power supply (5) -Resistor R3-Varicap D2→
A tuning voltage Vc is supplied to the varicap D2 through a loop of coil L2→resistor R2′→power supply (5).

Therefore, the tuning frequencies of the tuning circuits (11, (21) change in conjunction with the tuning voltage Vc.

In this case, the resonant current 11 of the tuned circuit (1) is
Element L1. D1. Flows through the loop of C1, and the tuned circuit (2)
The resonant current I2 of element L2. D2. The current 11 does not flow through the capacitor c2, and the current 2 does not flow through the capacitor C. Therefore, even if there is some impedance in the capacitors 9C1 and C2, no interference will occur between the tuned circuits [1] and (2).
Therefore, abnormal oscillation and unstable operation will not occur.

In the above description, the number of varicaps in the tuning circuit and the composite varicap is two, but a similar configuration can be made in the case of three or more.

〔Effect of the invention〕

The resonant current ■1 of the tuned circuit (1) is the element LL, D1°0
1, the resonant current I2 of the tuned circuit (2) is:
Element L2. D2. The current (1) does not flow through the capacitor C2, and the current (2) does not flow through the capacitor C1. Therefore, even if there is some impedance in the capacitors C1 and C2, the tuned circuits (1) and (2) ), therefore, there is no possibility of abnormal oscillation or unstable operation.

Furthermore, the configuration for this purpose is extremely simple.

[Brief explanation of drawings]

FIGS. 1 and 2 are connection diagrams of an example of the present invention, and FIGS. 3 to 6 are diagrams for explaining the same. (11, (21 is the tuning circuit. Fig. 2 Fig. 3 The concave road entrance of human power death Fig. 4

Claims (1)

[Claims] A composite variable capacitance diode having a plurality of variable capacitance diodes, one electrode of which is taken out as an independent terminal, and the other electrode taken out as a common terminal. In a tuning circuit device in which the plurality of variable capacitance diodes are respectively connected as tuning elements to a plurality of tuning coils, the independent terminals of the plurality of variable capacitance diodes are
Each of the plurality of variable capacitance diodes is directly connected to one terminal of the tuning coil, and the common terminal of the plurality of variable capacitance diodes is
Each is connected to the other terminal of the tuning coil through a bypass capacitor, and a control voltage is supplied in parallel to the plurality of variable capacitance diodes through a decoupling resistor, and the tuning frequency of the plurality of tuning circuits is controlled by this control voltage. A tuned circuit device that allows the changes to be made in conjunction with each other.