JPS58153406A - Oscillator for voltage control - Google Patents

Abstract

PURPOSE:To separate the distance between an earth and a connection point and to reduce floating capacity by connecting one end or all of a series/parallel variable capacity diodes to a bias supplying circuit through space at the mounting of the variable capacity diodes. CONSTITUTION:Both end parts 17, 18 of variable capacity diodes 9, 10, 11, 12 in a series connecting part is fixed on a printed board 20, a main body, to connect both end parts 17, 18 electrically with other circuits and make themselves pole braces to be connected to other variable capacity diodes 10, 11 and bias supplying circuit 15, 16 at connection parts 13, 14 through space. Thus an earth pattern on the printed board can be separated from the connection parts 13, 14, so that the floating capacity can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a voltage controlled instant oscillator (VCO) in which variable capacitance diodes are arranged in series and parallel in multiple stages.

For example, a VCO can be described as shown in Fig. 1, in which a variable capacitance diode 2 is used to apply a bias to a part of the capacitance of the resonant part connected in series to the resonant coil 1 of the oscillator. Voltage (tuning voltage vT)
By using the fact that the capacitance changes, it is coupled to the resonant coil 1 by the fully coupled circuit 3, and the oscillation frequency determined by the oscillator and the oscillation transistor circuit 4 is changed. be. Note that the power to the transistor circuit 4 is supplied from a power supply circuit 5, and the output thereof is taken out via a coupling circuit 6.

Usually, the variable capacitance diode circuit 2 is shown as shown in Fig. 5g2, so the number of variable capacitance diodes 7 used for vCO is one or at most two. In this case, it could be mounted on a printed circuit board like other parts. Note that the tuning voltage vT is supplied by a high frequency choke coil 8.

However, the situation becomes different when a method of configuring variable capacitance diodes in multiple stages in series and parallel as shown in FIG. 3 is used in order to realize high performance and wide range CO.

First, a method of configuring variable capacitance diodes in series and parallel in multiple stages will be described. The connection method shown in FIG. 3 is considered to be the most efficient method with the least number of parts. That is, one or more parallel-connected variable capacitance diodes 9, 10° 11, and 12 with the same electrodes are connected back-to-back in multiple stages, and each cathode connection portion 13, 1 is connected in multiple stages.
A bias supply circuit 15, 16'i such as a high frequency choke to which a DC voltage is applied is connected to 4, and each anode connection part is connected to an anode connection part 1'7 at the lowest end.
is grounded, and the remaining anode connection part 18 is DC grounded via the bias supply circuit 19. At this time, as shown in the mounting plan view a and the mounting side view of FIG. Diode 9~12f! : All printed circuit board 2
It will be mounted on the electrode pattern provided at 0. In this case, even if the bias supply circuits 15, 16, and 19 have sufficiently high impedance in terms of high frequency, the printed circuit board 2
If is made of epoxy glass, each cathode connection 13°14
between the electrode pattern and the ground 21, or between the pattern 18 of each anode connection part and the ground 21.
Since there is a stray capacitance of 4PF8 degrees, the absolute value of the variable capacitance value becomes large, resulting in a drawback that the effective capacitance variable width becomes narrow. This phenomenon becomes more noticeable as the variable capacitance diodes are connected in series in multiple stages, as the overall capacitance of the variable diodes becomes smaller, so the effect of stray capacitance increases and becomes more noticeable. '1.
As the electrode patterns are connected in parallel in multiple stages, the electrode pattern becomes wider, so the stray capacitance becomes larger, and the phenomenon becomes more pronounced in this case as well. The embodiment shown in FIG. 4 corresponds to the circuit connection diagram shown in FIG. 3.

Further, other drawbacks caused by stray capacitance include the following. When operating as a VCO, a high frequency voltage is applied to each stage of the variable capacitance diode. Assuming that the sum of the parallel connections of variable capacitance diodes is Cv per stage and the stray capacitance C8 is equal for each stage, the total capacitance CM at N stages is as follows, assuming that the bias supply circuit has high impedance at high frequencies.

C,=CV+C8 Therefore, since the equivalent capacitance of each stage is not equal to 1/N, the high frequency voltage applied to each stage will be unbalanced. If the stray capacitance is C8-0, the equivalent capacitance of each stage is 1/N. If there is a high frequency voltage imbalance,
There is a stage where a large amount of high-frequency voltage is applied, where the influence of nonlinear distortion of the variable diode becomes large, and the receiver suffers from untuned n1 cross-modulation interference, deterioration of C/N (carrier-to-noise ratio), etc. Occur. Therefore, it is necessary to reduce the stray capacitance and reduce the unbalance of the high frequency voltage applied to the variable capacitance diode.

The present invention aims to improve customization of the VCO, such as by increasing the variable frequency range, by creating a structure that reduces stray capacitance.

Embodiments of the present invention are shown in FIGS. 5, 6, and 8.

As shown in FIG. 3, as a mounting method for variable capacitance diodes 9 to 12 connected in series and parallel with the same electrodes in multiple stages t', in the example shown in FIG. Rather than using a prepared electrode pattern,
Spatially connected directly with the bias supply circuit 15, 16, such as a high frequency choke, by soldering or otherwise.
It is characterized by With this mounting method, the distance between the spatially connected cathode electrode connection parts 13 and 14 of the variable capacitance diode and the ground pattern 21 of the main body printed circuit board 2o is large, and the stray capacitance between them can be significantly reduced. can. Note that 17.18 is the anode/j connection part,
In this case, the former is connected to or also serves as the earth shield 21.

The embodiment of FIG. 6 is almost the same as that of FIG. 5, and the same parts are given the same numbers and their explanations are omitted.
．． Cathode electrode connection part j3.1 for connection, such as 16
This is an example in which the auxiliary substrate 22 is provided with a 4-metal gold pattern, which has a small stray capacitance and is easy and reliable to mount. However, in order to reduce stray capacitance, this auxiliary board 22 is not provided with a ground pattern, and is only used as a holder for three-dimensionally mounting components by floating it from the main printed board 2o.

To explain with a more specific example, when an even number of variable capacitance diodes are connected in series, - for example, six variable capacitance diodes are connected in parallel and four in series as shown in FIG. Consider the case where In the figure, 6 of the variable capacitance diodes 25 to 30 are connected in parallel.
In the same way, the other six variable capacitance diode groups connected in parallel are considered to be variable capacitance diode groups 32, 33, and 34, respectively. 13 and 14 are cathode electrode connection portions 17, 18 and 23 are anode electrode connection portions 15, 16, and 19 and 24 are bias supply circuits.

FIG. 8 shows a method of mounting the circuit configuration of FIG. 7 according to the present invention. A is a plan view, b is a side view, and C is a front view, and the numbers correspond to those in FIG. 7. In this embodiment, the cathode electrode connecting portions 13, 14 are suspended from the main grid substrate 2o and directly connected with wires, solder, or the like. In this mounting method, the anode side electrode connection part 17.18.23 is connected to the main body printed circuit board.
Since the electrodes of the variable capacitance diodes are all oriented in the same direction, such as 4 being spatially connected, assembly errors are less likely to occur and mounting is easy. A bias supply circuit 19.24 is connected to the anode-side electrode connection portion 18.23 on the printed circuit board that has been disconnected and is grounded in a direct current manner (the anode electrode connection portion 17 is directly grounded and connected to the ground pattern 21). ), and the bias supply circuits 15 and 16 are connected to the spatially connected cathode side electrode connection parts 13 and 14, and the bias supply circuit is supplied with the DC-cheating voltage vT. There is also a need for uniformity in the implementation. In this mounting method, the variable capacitance diode is mounted upright on the printed circuit board as shown in the side view of FIG. 8, so the mounting space is small and it is suitable for miniaturization.

The voltage controlled oscillator of the present invention has the following effects.

That is, the distance between the electrode connection portion and the ground can be increased, and stray capacitance can be reduced.

As a result, the absolute value of the overall capacitance of the variable capacitance diode increases and the variable capacitance width narrows, which is the effect of stray capacitance = w
i can be made smaller.

Furthermore, the mounting area of the entire variable capacitance diode can be reduced, making it suitable for miniaturization. Also, if the mounting area is the same, you can get some margin in the distance between the electrical pattern and the ground pattern on the printed circuit board.
Stray capacitance can be reduced.

As described above, according to the present invention, by mounting part or all of the variable capacitance diodes connected in series and parallel in multiple stages with the same electrodes floating above the printed circuit board, the power saving and grounding of the variable capacitance diodes can be reduced. By reducing the stray capacitance between It has many advantages such as suitability, and its industrial value is extremely large.

[Brief explanation of drawings]

Figure 1 is a system diagram of a voltage controlled oscillator (VCO), Figure 2 is a wiring diagram of a vCO variable capacitance diode circuit, and Figure 3 is a diagram of a voltage controlled oscillator (VCO).
A wiring diagram of a variable capacitance diode circuit connected in series and parallel in multiple stages, Fig. 4d is a plan view showing the conventional mounting state of the circuit in Fig. 3, Fig. 4 is a side view thereof, and Fig. 5 is a diagram of the main circuit. FIG. 6 is a side view showing the mounting state of one embodiment of the invention; FIG. 6 is a side view showing the mounting state of another embodiment of the invention; FIG. 7 is a diagram of another specific embodiment; FIG. 8a 7 is a plan view showing a state in which the present invention is implemented in the circuit of FIG. 7, b is a side view thereof, and C is a front view thereof. 1... Resonant coil, 2... Variable capacitance diode circuit, 3... Coupling circuit, 4...
...Oscillation transistor circuit, 6...Power supply circuit, 6
...... Coupling circuit, 7... Variable capacitance diode, 8... High frequency choke coil for bias, 9 to 12... Variable capacitance diode group, 13,
14... Cando acid electrode connection part (pattern, 15
．． 16...Bias supply circuit, 17...
Anode electrode pattern (same as ground pattern), 18
...Anode electrode connection part (pattern), 19...
...Bias supply circuit, 2oze...(main body) printed circuit board, 21...earth pattern, 22...
... Auxiliary board, 23 ... Anode electrode connection part (pattern), 24 ... Bias supply circuit, 2
6-30... Variable capacitance diode, 31-34
...Variable capacitance diode group. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 - Vτ Figure 7

Claims (2)

[Claims] (1) The same electrodes of a plurality of variable capacitance diodes connected in parallel are connected in series in multiple stages, and a bias supply circuit to which DC voltage is applied is connected to each cathode connection, and the anode connection is , only the one at the extreme end is grounded, and the remaining anode connections are configured to be DC grounded via a bias supply circuit. 1. A voltage controlled oscillator characterized in that the entire part is not directly connected using electrodes provided on the printed circuit board, but is connected together with a bias supply circuit of a variable capacitance diode spatially above the printed circuit board. (2) It has an even number of variable capacitance diodes connected in series, and the anode connection part is set on the printed circuit board, and the cathode connection part is connected spatially above the printed circuit board together with the bias supply circuit. A voltage controlled oscillator according to claim 1, characterized in that: