JP2000357921A - Voltage-controlled oscillator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To miniaturize a trimming pattern and to enlarge the adjusting range of oscillation frequency. SOLUTION: A resonation part 2 for deciding an oscillation frequency and an oscillation circuit 3 performing oscillation with the oscillation frequency which is set by the resonation part 2 constitute a voltage-controlled oscillator. The resonation part 2 has a strip line SP. Plural inductors L2 and L3, whose ends are shorted and invalidated by surface patterns P1 and P2, are connected in series to the strip line SP. The corresponding inductors L2 and L3 can be validated by cutting the surface patterns P1 and P2. Even in a extensive adjustment of the frequency, which is difficult by a trimming pattern, the oscillation frequency can be adjusted roughly in an adjustable range by cutting the surface patterns P1 and P2 at any time. Thus, the adjusting range can be enlarged, and the oscillation frequency by the trimming patterns can be adjusted finely.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to VHF / UH
The present invention relates to a voltage controlled oscillator (VCO) used for a radio device or the like using a high frequency in the F band, and more particularly to an oscillation frequency adjustment mechanism.

[0002]

2. Description of the Related Art A voltage controlled oscillator (VCO) is generally composed of a resonating portion for determining an oscillation frequency and an oscillation circuit for maintaining an oscillation state at the oscillation frequency set by the resonating portion. FIG. 5 shows a specific circuit configuration of the conventional voltage controlled oscillator 1. As shown in FIG.
Is a stripline resonator using stripline SP, the varactor diode capacitance C _D by the resonant frequency F [F = 1 in D to be described later inductance and capacitance of the capacitor C7 connected in parallel to the strip line SP / 2π√L (C +
C _D )], the oscillation frequency is determined.

[0003] Since this oscillator is a voltage-controlled oscillator, it has a varactor diode D as a variable capacitance element that changes with a DC applied voltage Vc, and a coupling capacitor C1.
Is connected to the resonator via a. On the other hand, the oscillation circuit 3 includes two transistors Tr connected in cascade.
1 and Tr2, the capacitor C6 is connected to the transistor Tr1 so that the collector is grounded at high frequency, and the capacitors C4 and C5 are connected between the base of the transistor Tr1 and ground. The resonance section 2 and the oscillation circuit 3 are connected via a capacitor C2 to form a Colpitts oscillator.

That is, oscillation occurs in the feedback loop at the resonance frequency of the resonance section 2, and its emitter output is input to the base of the transistor Tr2 via the capacitor C3, so that oscillation of a predetermined frequency from the collector side occurs. An output signal OUT is obtained. Therefore, the oscillation output signal OU can be changed by varying the DC applied voltage Vc.
The frequency of T can be arbitrarily controlled within a predetermined range.

[0005] By the way, in this type of VCO, the variation in VC characteristics due to variations in the characteristics of the elements used and variations in the circuit constants and the like.
Oscillation frequency at a constant DC applied voltage with respect to the reference frequency of O slightly varies. For this reason, conventionally, a conductor pattern for adjustment, that is, a trimming pattern is provided in series with the strip line SP, and the trimming pattern is trimmed as needed according to the variation with respect to the reference frequency (see the trimming pattern TP in FIG. 4). Thus, a fine adjustment is made to a target reference frequency by forming a predetermined inductor. In addition, this trimming processing is usually performed by laser cutting in addition to mechanical means such as a mini-tater or a cutter.

[0006] According to this method, since the inductor is formed in series with the strip line SP, fine adjustment in the direction of lowering the oscillation frequency is evident from the above-described equation for calculating the resonance frequency. It is possible.

[0007]

However, in the above-described frequency adjustment, for example, the frequency band to be used is 100 to
In a high-frequency range such as 600 MHZ, the size of the component becomes large because the resonant inductor is too large and the trimming pattern corresponding to it is also required to be large. Further, in the case of a product in which the reference frequency greatly changes, it may not be possible to cope with only the trimming pattern having the conventional structure. In such a product, constants of circuit components need to be changed for frequency adjustment, which is a problem in terms of commonality of components and productivity.

In addition, since the conventional method is to adjust the inductance of the resonance section in a direction to increase the inductance as described above, if the oscillation frequency before the adjustment is lower than the reference frequency, trimming is performed regardless of the deviation width. There was a problem that the frequency could not be adjusted by the pattern.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to reduce the size of an oscillation frequency adjustment pattern and to make it easy to adjust the oscillation frequency. An object of the present invention is to provide a voltage controlled oscillator that enables frequency adjustment by a trimming pattern even when the frequency is lower than the frequency.

[0010]

That is, according to the first aspect of the present invention, a resonance section (2) for determining an oscillation frequency and an oscillation for maintaining an oscillation state at the oscillation frequency set by the resonance section (2). In the voltage controlled oscillator (1) configured with the circuit (3), the resonance unit includes a strip line (S
P) and the strip line (SP)
Has at least one or more inner-layer inductors (L) whose both ends are short-circuited by the surface layer patterns (P1, P2) and are invalidated.
2, L3) are connected in series, and the corresponding inductors (L2, L3) are enabled by cutting the surface layer pattern (P1, P2).

In this configuration, when a large frequency adjustment that is difficult with the trimming pattern is required, the oscillation frequency is roughly adjusted within the adjustable range by cutting the surface layer pattern and enabling the corresponding inner layer inductor. be able to. As a result, the adjustment range can be widened, and after the coarse adjustment, the oscillation frequency can be finely adjusted by using a small trimming pattern, so that the trimming pattern can be downsized.

According to the second aspect of the present invention, the resonance unit (2) for determining the oscillation frequency and the oscillation circuit (3) for maintaining the oscillation state at the oscillation frequency set by the resonance unit (2) are used. In the voltage controlled oscillator (1) configured,
The resonance section (2) has a strip line (SP), and at least one or more capacitors (C10, C11) are connected in parallel to the strip line (SP) by a surface layer pattern (P3, P4). Connected, and by cutting the surface pattern (P3, P4),
It is characterized in that the corresponding capacitors (C10, C11) are invalidated.

In the above configuration, the surface layer pattern is cut,
Since the oscillation frequency can be increased by disabling the corresponding capacitor and reducing the total capacitance of the resonance section, the frequency can be adjusted even when the pre-adjustment frequency is lower than the reference frequency.

According to a third aspect of the present invention, in the first aspect, at least one capacitor is connected in parallel to the strip line (SP) by a surface layer pattern (P3, P4). By cutting the surface pattern (P3, P4), the corresponding capacitors (C10, C11) are invalidated.

As described above, by providing a mechanism for roughly adjusting the oscillation frequency by the inductor connected in series to the strip line and the capacitor connected in parallel, the pre-adjustment frequency fluctuates around the reference frequency. Even so, the oscillation frequency can be roughly adjusted within the adjustable range.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a voltage controlled oscillator (hereinafter referred to as VCO) according to the present invention will be described below with reference to the drawings. To simplify the description, the same reference numerals are used in the following description for portions common to the related art.

FIG. 1 is a circuit diagram showing an embodiment of a portion of a resonance section 2 according to the VCO of the present invention. Here, the oscillation circuit 3 has a circuit configuration similar to the conventional one, and is not shown. FIG. 4 shows the component mounting state of FIG. 1 and shows only a portion related to the resonance section 2.

The configuration of the resonance section 2 in this embodiment is basically the same as that of the conventional one, and is constituted by a resonator using a strip line SP, and is connected to this resonator via a coupling capacitor C1. A varactor diode D whose capacity can be changed by a DC voltage is connected to change the oscillation frequency according to an external control voltage (VC).

The strip line SP is formed in an inner layer portion of the substrate Pt, and one end thereof is provided with a through hole TH4.
Through the coupling capacitor C
1 is pattern-connected. This stripline S
At the other end of P, inductors L2 and L3 for coarse frequency adjustment, each having a different inductance value, formed on the inner layer of the substrate via through holes TH1 to TH3, and a trimming pattern TP for fine frequency adjustment formed on the surface layer of the substrate. Are connected in series, and the through holes TH
1, TH2 and TH3 are each a surface pattern P
1 and P2, whereby the inductors L2 and L3 in the inner layer are in an invalid state. In this embodiment, each inductance is L2 <L.
3 are set to different values.

Further, surface layer patterns P3 and P4
The capacitors C10 and C11 are connected in parallel to the strip line SP via the through holes TH4. The capacitors C10 and C11 and the inductor L1 and the inner layer inductors L2 and L3 of the strip line SP form an LC resonance circuit. are doing.

By the way, conventionally, the oscillation frequency of the VCO generated due to the variation of the used element or the like is set to the value of the strip line SP.
As described above, the adjustment is performed by the trimming pattern TP formed in series with the above. The present invention is a measure to cope with the case where the variation of the frequency before adjustment is too large to make fine adjustment to the reference frequency difficult, and the surface layer patterns P1 to P4 are cut by laser or mechanical means as needed. By doing so, it is possible to finely adjust the oscillation frequency without replacing parts as in the related art. The specific adjustment method will be described with reference to the following example.

The oscillation frequency is adjusted by measuring a frequency (initial frequency) when a predetermined DC voltage is applied to the control voltage terminal (VC) of the VCO, and comparing this with a reference frequency determined by a resonance circuit constant. This is performed by detecting the state of the deviation.

First, in the first example, as a result of the above detection, the initial frequency is too high and the frequency cannot be kept within the adjustable range in the trimming pattern TP.

In this case, since it is necessary to adjust the initial frequency in the lower direction, the cut processing of the surface layer pattern P1 or P2 is performed. In this example, the initial frequency is finely adjusted by the trimming pattern TP by cutting the surface layer pattern P1 from the degree of deviation from the reference frequency, enabling the inductor L2 having a small inductance and increasing the total inductance of the resonance unit 2 by that amount. Try to stay within the possible range. Incidentally, the pattern cut portion is the cut portion B shown in FIG.

After the coarse frequency adjustment by the surface layer pattern P1,
The trimming pattern TP may be finely adjusted to a reference frequency by trimming the trimming pattern TP into a shape as shown by a symbol A in FIG. As a result of the detection, if the variation of the initial frequency is within a range in which fine adjustment by the trimming pattern TP is possible, fine adjustment may be performed in the conventional manner.

FIG. 2 is an equivalent circuit after adjustment of the resonance unit 2. In this example, the total inductance of the resonance unit 2 is L1.
+ L2 + (inductance of trimming pattern TP)
And the total capacitance is C10 + C11 + C1 × C
_D / (C1 + _CD ). Here, CD is the capacitance of the varactor diode _D represented by a DC voltage.

In the following example, contrary to the above example, the initial frequency is too low and the adjustment is difficult with the trimming pattern TP.

In this case, it is necessary to adjust the initial frequency to a higher value.
4 is performed. In this embodiment, the surface layer pattern P4 is cut from the degree of deviation from the reference frequency, and the capacitor C
By disabling 11, the capacitance of the resonance unit 2 is reduced by that amount, and the oscillation frequency is roughly adjusted in a higher direction so as to be within the finely adjustable range by the trimming pattern TP. Incidentally, the pattern cut portion is the cut portion C shown in FIG.

FIG. 3 is an equivalent circuit at this time. In this example, the total inductance of the resonant part 2 L1 + (inductance trimming patterns TP), and the total capacitance becomes C10 + _{C D.}

As described above, according to the present embodiment, when a large frequency adjustment that cannot be dealt with by the trimming pattern TP is required, the corresponding surface layer pattern is cut as needed to adjust the oscillation frequency. Can be roughly adjusted within. As a result, the variation in frequency over a wide range can be reduced by a relatively small trimming pattern T.
Fine adjustment can be made with P. Therefore, it is not necessary to change the constants of the parts as in the related art, so that the parts can be shared and the productivity can be improved. In addition, since the rough adjustment may be a simple process of cutting the surface layer pattern, the adjustment operation is easy.

As described above, in the present embodiment, two inner-layer inductors and two capacitors constituting the frequency adjusting mechanism are used. However, the present invention is not limited to this, and at least one or more may be used. Further, their inductance and capacitance may be set the same or may be set differently.

[0032]

As described above, according to the first aspect of the present invention, there is provided a resonator configured to determine an oscillation frequency and an oscillation circuit configured to maintain an oscillation state at the oscillation frequency set by the resonator. In the voltage controlled oscillator described above, the resonance section has a strip line, and at least one or more inner layer inductors whose both ends are short-circuited by a surface layer pattern and invalidated are connected in series to the strip line. Since the corresponding inductor is enabled by cutting the surface layer pattern, the corresponding surface layer pattern is cut when a significant frequency adjustment that is difficult with the conventional trimming pattern is required. By activating the inner layer inductor, the oscillation frequency can be roughly adjusted within the adjustment range.
As a result, the adjustment range can be widened, and fine adjustment can be performed with a relatively small trimming pattern after the coarse adjustment, so that the trimming pattern can be downsized. In addition, since the rough adjustment may be performed by cutting the surface layer pattern, the adjustment operation is easy.

According to the present invention described in claim 2,
In a voltage-controlled oscillator configured by a resonance unit that determines an oscillation frequency and an oscillation circuit that maintains an oscillation state at an oscillation frequency set by the resonance unit, the resonance unit has a strip line, and the strip line At least one or more capacitors are connected in parallel by the inner layer pattern, and the corresponding capacitor is invalidated by cutting the surface layer pattern, so by cutting the corresponding surface layer pattern, Since the total capacitance of the resonance section can be reduced, it can be adjusted in a direction to increase the oscillation frequency. Therefore, frequency adjustment when the frequency before adjustment is lower than the reference frequency, which has been difficult in the past, can be performed. In this case, the rough adjustment can also be performed by the surface layer pattern cutting process as described above, so that the adjustment operation is easy.

According to the third aspect of the present invention,
Since the oscillation frequency coarse adjustment mechanism using the inductor and the capacitor is provided, the oscillation frequency can be roughly adjusted within the adjustable range, even if the frequency before adjustment varies with respect to the reference frequency. Can be. Thereby, commonality of parts and improvement of productivity can be achieved.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing an embodiment of a resonance unit according to the voltage controlled oscillator of the present invention.

FIG. 2 is a circuit diagram of a resonance unit when the oscillation frequency is roughly adjusted.

FIG. 3 is a circuit diagram of a resonance unit in a case where coarse adjustment of an oscillation frequency different from that in FIG. 2 is performed.

FIG. 4 is a component mounting diagram showing a main part of the voltage controlled oscillator.

FIG. 5 is a circuit diagram of a conventional voltage controlled oscillator.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Voltage controlled oscillator 2 Resonator 3 Oscillation circuit SP Strip line P1-P4 Surface pattern L2, L3 Inner layer inductor C10, C11 Capacitor

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yoji Yauchi 5-36-11 Shimbashi, Minato-ku, Tokyo Inside Iwaki Electronics Co., Ltd. (72) Inventor Hidekazu Takahashi 5-36-11 Shimbashi, Minato-ku, Tokyo F term (reference) in Electronics Corporation 5J006 HB01 HB03 HB14 HB15 HB21 5J081 AA03 AA11 CC07 CC22 DD21 EE09 EE18 GG01 JJ14 JJ23 KK02 KK09 KK22 LL01 MM01

Claims (3)

[Claims] 1. A voltage-controlled oscillator (1) comprising a resonance section (2) for determining an oscillation frequency and an oscillation circuit (3) for maintaining an oscillation state at the oscillation frequency set by the resonance section (2). The resonating unit (2) has a strip line (SP), and at least one of the strip lines (SP) whose both ends are short-circuited by the surface pattern (P1, P2) and invalidated. The above inner layer inductors (L2, L3)
Are connected in series, and the surface pattern (P1, P1
A voltage-controlled oscillator characterized in that the corresponding inductors (L2, L3) are enabled by cutting off (2). 2. A voltage controlled oscillator (1) comprising a resonator (2) for determining an oscillation frequency and an oscillation circuit (3) for maintaining an oscillation state at the oscillation frequency set by the resonator (2). The resonance section (2) has a strip line (SP), and at least one or more capacitors (C10, C11) are parallel to the strip line (SP) by a surface layer pattern (P3, P4). And by cutting the surface pattern (P3, P4),
A voltage controlled oscillator, wherein the corresponding capacitors (C10, C11) are disabled. 3. At least one capacitor (C10, C11) is connected in parallel to the strip line (SP) by a surface layer pattern (P3, P4), and the surface layer pattern (P3, P4). The voltage controlled oscillator according to claim 1, wherein the corresponding capacitors (C10, C11) are invalidated by disconnecting the capacitors.