JPH11112207A - High frequency circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the deterioration and the loss of a carrier/noise ratio(C/N) by switching a system to first TEM resonance or the first TEM resonator and a second resonator, which are mutually connected, in accordance with the state of a switch control signal. SOLUTION: A circuit is constituted of the double end open TEM resonator DR1, the one end short-circuit TEM resonator DR2, high frequency switch diodes D1 and D2 and a capacitor Co . The high frequency switch diodes D1 and D2 are switch means. The system can be switched to the first TEM resonator DR1 or the first TEM resonator DR1 and the second TEM resonator DR2, which are mutually connected, in accordance with the state of the switch control signal applied to the switch means. Namely, either one of two resonance frequencies can be realized by setting the high frequency switch diodes D1 and D2 into short-circuit state/open state.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dual band portable telephone. A mobile radio terminal, for example, a mobile phone has a problem that available frequencies are insufficient with an increase in users.

As a countermeasure, there is a method in which a portable telephone is provided with a function capable of transmitting and receiving a plurality of frequency bands so that when there is no free channel in one frequency band, the channel of the other frequency band can be used. .

At this time, it is necessary for the high frequency circuit of the dual-band portable telephone to improve the carrier / noise ratio (hereinafter abbreviated as C / N) and improve the passage loss.

[0004]

2. Description of the Related Art There is a problem that a usable frequency of a mobile phone is insufficient with an increase in users, but as a countermeasure, there is a dual band of a mobile phone.

[0005] The dual band means that a portable telephone has a function of transmitting and receiving a plurality of frequency bands. That is, a channel of one frequency band (for example, 8
When all 10 MHz to 828 MHz are in use, the channel of the other frequency band (eg, 87
0 MHz to 885 MHz).

Therefore, as a countermeasure to cope with the dual band, the high frequency part of the portable telephone is set to 810 MHz to 8 MHz.
The most common measure was to widen the band so as to cover the entire 85 MHz band.

[0007]

As described above, in order to increase the bandwidth of the high-frequency section, the components of the high-frequency section must be broadened.

[0008] However, the following problems occur when the band of the component is widened. 1. Deterioration of C / N For example, in a voltage-controlled oscillator or the like, the C / N is degraded as the frequency range to be controlled is wider (C / N is a factor that greatly affects wireless communication quality). 2. For example, in the case of a filter, the attenuation ratio between the frequency to be passed and the frequency not to be passed is lower as the pass band is wider. The amount of attenuation is obtained.

In this case, the insertion loss increases by the number of stages of the filter. In order to solve the above problem, it is sufficient to divide the components into only the band to be used and use a plurality of them in combination. However, in this case, the number of components is doubled, and the size of the mobile phone is not reduced. .

SUMMARY OF THE INVENTION It is an object of the present invention to improve C / N deterioration and loss.

[0011]

FIG. 1 is a diagram illustrating the principle of the first and second embodiments of the present invention (part 1), and FIG. 2 is a diagram illustrating the principle of the first and second embodiments of the present invention (part 2). .

According to a first aspect of the present invention, a first TEM resonator and a second TEM resonator are connected via switching means. The first TEM resonator or the first and second TEM resonators connected to each other can be switched according to the state of the switching control signal applied to the switching means. I made it.

According to a second aspect of the present invention, the first TEM resonator and the second TEM resonator are constituted by a TEM resonator having both ends open and a TEM resonator having one end short-circuited. According to a third aspect of the present invention, a circuit in which the TEM resonator having both ends open and the TEM resonator having one end short-circuited is connected via switching means, at least two times.
To form a multistage bandpass filter.

The switching means can cover two frequency bands. Where TEM
In the case of a resonator, what determines the resonance frequency is the length of the resonator itself, and it is difficult to change this length mechanically.

For this reason, the TEM resonator is operated as an inductance component to resonate with the capacitor. Also, in the present invention, a combination of TEM resonators, at least one high-frequency switch diode is used between them, and the resonance frequency is controlled by turning on / off the diode, so that the shape of the component is not increased, It is designed to support a plurality of frequency bands.

Hereinafter, the first and second principles of the present invention will be described with reference to FIGS. The resonance circuit in FIG. 1, FIG. 2, open ends TEM resonator DR1, one end shorted TEM resonator DR2, is composed of a high-frequency switching diodes D1, D2 and capacitor C _0. The high frequency switch diodes D1 and D2 are switching means.

First, when a TEM resonator is used, it is used in a region where the resonator resonates or a region exhibiting inductive properties. Therefore, when both ends are open, (λ _g / 2) T
In the range of EM length ≦ λ _g / 2, if one end is short-circuited, (λ _g
/ 4) Use in the range of TEM length ≦ λ _g / 4. Note that λ
_g : wavelength in a coaxial line.

A capacitor C _{0 is connected} to the TEM resonator DR1.
, Resonance occurs at the frequency F ₀ and the impedance becomes minimum, but the impedance increases at frequencies farther from the frequency F ₀ (FIG. 1 (a)-, FIG. 1).
(B)-see).

Further, the right end of the TEM resonator DR1 grounded via the high frequency switch diode D1, when the diode D1 is short-circuited, the resonator DR1 resonates at a frequency of F _0/2, the resonance frequency Then, the impedance becomes minimum (see FIG. 1 (a)-, FIG. 1 (b)).

This is because the switching operation of the high-frequency switch diode D1 causes the TEM resonator DR1 to change from the state where both ends are open to the state where one end is short-circuited. Further, a TEM resonator DR2 having one end short-circuited is connected in series to the TEM resonator DR1 shown in FIG. 1 (a)-via a high frequency switch diode D2 (see FIG. 2 (a)-).

The diode D1 for the high frequency switch
The short-circuit state, when the high frequency switch diode D2 in the open state FIG. 2 (a) - becomes a structure of, resonates at frequency F _1, the impedance is minimized at a frequency F ₁ (FIG. 2 (b) - see) .

Conversely, when the high-frequency switch diode D1 is opened and the high-frequency switch diode D2 is short-circuited, the configuration shown in FIG. 2A is obtained, and the resonance frequency becomes higher than that of the configuration shown in FIG. The resonance frequency is reduced by the addition of the TEM resonator DR2 short-circuited at one end (for example, Δf) (see FIG. 2B).

That is, in the circuit configuration of FIG. 2, by setting the high-frequency switch diodes D1 and D2 to the short-circuit state / open state, one of the two resonance frequencies can be realized.

[0024]

3A and 3B are explanatory diagrams of a third embodiment of the present invention. FIG. 3A is a circuit diagram, FIG. 3B is a frequency: loss characteristic diagram, and FIG. 4 is a diagram in FIG. In the mounting explanatory diagram of the dotted line part,
(A) is a perspective view of a main part, and (b) is a side view of (a).

FIGS. 5A and 5B are explanatory diagrams of another embodiment of the third invention, wherein FIG. 5A is a circuit diagram, and FIG. 5B is a frequency: loss characteristic diagram. Hereinafter, FIGS. 3 to 5 will be described.

It should be noted that the parts described in detail above will be described briefly, and the parts of the present invention will be described in detail.
A description will be given using a band-pass filter which is considered to be more effective by implementing the present invention.

Also, since the present invention does not depend on the number of sections, it has a simple two-stage structure and a TEM length <λ.
_g / 2, TEM length <λ _g / 4. Further, the same reference numerals are the same objects throughout the drawings.

Now, C2, C4, and C5 in FIG. 3A are coupling capacitors, and their values are determined by specifications required by the device. C1, C3: capacitors for resonance that affect the characteristics of the band-pass filter, and their values are determined by specifications required by the device side.

Note that this capacitor has a TEM length = λ _g /
2. Not required when TEM length = λ _g / 4. C6: Capacitors for preventing high frequency components from entering the bi-eye circuit D1 to D4: High frequency switch diodes (PIN diodes) DR1, DR2: TEM resonators open at both ends DR3, DR4: TEM resonators shorted at one end ch1, ch2: It is a choke coil to prevent high frequency components from going around the bias circuit.

Here, when a positive voltage is applied to the control terminal,
The high-frequency switch diodes D3 and D4 are short-circuited, and the high-frequency switch diodes D1 and D2 are open.

Therefore, the open-ended TEM resonator DR1, the open-ended TEM resonator DR3, and the open-ended TEM resonator D3
R2 and the one-end short-circuited TEM resonator DR4 are connected to each other.

The frequency: loss characteristic at this time is shown in FIG.
- transmission loss at a frequency f ₁ ± Delta] f becomes minimum as shown in, loss increases as the distance from the frequency f ₁ ± Δf. That is, the first resonance having a resonance frequency determined by the total inductance component L13 of the capacitance value of the capacitor C1, the inductance component L1 of the series-connected open-ended TEM resonator DR1, and the inductance component L3 of the single-ended short-circuit TEM resonator DR3. Circuit, the capacitance value of the capacitor C3, the inductance component L2 of the series-connected open-ended TEM resonator DR2, and the short-circuited TEM resonator DR
And a second resonance circuit having a resonance frequency determined by the total inductance component L24 of the four inductance components L4.
The configuration is such that the components are coupled by the coupling capacitor C2.

As a result, a circuit having frequency selectivity as shown in FIG. 3B is obtained. Next, when a negative voltage is applied to the control terminal, the high-frequency switch diodes D3 and D4 are opened, but the high-frequency switch diodes D1 and D2 are short-circuited.

Thus, the one-end short-circuited TEM resonator DR3
And a one-end short-circuited TEM resonator DR4 are respectively provided with a corresponding open-ended TEM resonator DR1 and an open-ended TEM resonator DR.
2, and the other end of the TEM resonator DR1 connected to the capacitor C1 and the other end of the TER resonator DR2 connected to the capacitor C3 are short-circuited.

That is, a first resonance circuit having a resonance frequency determined by the capacitance value of the capacitor C1 and the inductance component L1 of the TEM resonator DR1 in which one end is short-circuited;
TEM with one end short-circuited with the capacitance value of capacitor C3
The second resonance circuit having a resonance frequency determined by the inductance component L2 of the resonator DR2 is coupled by a coupling capacitor C2.

Thus, a circuit having frequency selectivity as shown in FIG. 3B is obtained. Note that the resonance frequencies of the first and second resonance circuits are slightly shifted due to characteristic deviations of elements constituting the two circuits.

FIG. 4 is an explanatory view of the mounting of the dotted line portion in FIG. 3, where 1 is a dielectric substrate whose back surface is entirely grounded,
2 and 6 ground plane formed on the surface of the dielectric substrate, 3 is a microstrip line, 4 _1, 4 _2, 5 is a connection terminal.

Further, 7 and 8 are conductor portions, DR1 is a TEM resonator having both ends open, DR3 is a TEM resonator having one end short-circuited, and D
Reference numerals 1 and D3 denote high frequency switching diodes, and C1 and C4 denote capacitors.

Further, in the open-ended TEM resonator DR1 and the short-circuited TEM resonator DR3, the surface on which the connection terminals 4 ₁ , 4 ₂ , 5 are provided is the dielectric material as it is, but the other upper surface, side surface and The inner surface of the hole 9 into which the connection terminal is inserted is covered with, for example, a metal film.

Here, the high frequency switch diode D1
Is off and the high frequency switch diode D3 is on, the microstrip line 3, the capacitor C4
Signal of the frequency f ₁ input through the proceeds in the direction of the arrow without causing little loss.

However, the frequency f ₂ higher than the frequency f ₁
Is given a loss and is blocked here.
Conversely, when the high-frequency switch diode D1 is in the ON state,
When the high frequency switch diode D3 is off, a low frequency f ₁ of the signal than the frequency f ₂ is given loss is prevented here. (See FIG. 3B).

As shown in FIG. 5 (a), a TEM resonator DR1 open-ended at both ends and a short-circuited at one end T are connected to each other via switching means including high-frequency switching diodes D1 and D3.
Against EM resonator DR3, if the capacitor C1 is connected in series, a capacitor C1 and a TEM resonator operates as a series resonant circuit, as shown in FIG. 5 (b), for example, near the frequency f ₀ To block the passage of the frequency component.

Therefore, by combining the band pass filter shown in FIG. 3A and the band rejection filter shown in FIG. 5A, the frequency: loss characteristic shown in FIG.
A pole can be provided outside the passband.

That is, by practicing the present invention, it is possible to realize a configuration that can handle a plurality of frequencies with one component and does not impair the basic performance of the component.

[0045]

As described in detail above, the dual-band portable telephone has an effect that the C / N can be degraded and the loss can be improved.

[Brief description of the drawings]

FIG. 1 is a diagram (part 1) illustrating the principle of the first and second aspects of the present invention.

FIG. 2 is a diagram (part 2) illustrating the principle of the first and second embodiments of the present invention.

FIG. 3 is an explanatory view of a third embodiment of the present invention.

FIG. 4 is a mounting explanatory view of a dotted line portion in FIG.

FIG. 5 is an explanatory view of another embodiment of the third invention.

[Explanation of symbols]

First dielectric substrate 2 and 6 ground plane 3 microstrip line 4 _1, 4 _2, 5 connecting terminals 7 and 8 the conductor portions DR1, DR2 open ends TEM resonator DR3, DR4 one end short-circuit TEM resonator D1, D2, D3, D4 diode high frequency switch C _0, C1 -C6 capacitor Ch _1, Ch ₂ inductance

Claims (3)

[Claims] 1. A first TEM resonator is connected to a second TEM resonator via switching means, and the first TEM resonator is connected to the switching means according to a state of a switching control signal applied to the switching means. ,
Alternatively, the high-frequency circuit is configured to be switchable between the first TEM resonator and the second TEM resonator that are interconnected. 2. The first TEM resonator and the second TEM
The resonator is a TEM resonator with both ends open and a TEM with one end short-circuited.
2. The high-frequency circuit according to claim 1, wherein said high-frequency circuit comprises a resonator. 3. A multi-stage band-pass filter is formed by connecting at least two circuits in which a TEM resonator having both ends open and a TEM resonator having one end short-circuited are connected via switching means. 3. The high-frequency circuit according to claim 1, wherein said high-frequency circuit is configured to cover two frequency bands.