JP4637020B2 - High-frequency circuit module with tank circuit - Google Patents

Description

  The present invention relates to a high-frequency circuit module with a tank circuit, such as an amplifier and an oscillator, which uses the impedance of the tank circuit.

  Conventionally, as a high-frequency circuit module using a tank circuit, for example, there are various types of voltage-controlled oscillators disclosed in Patent Document 1.

  5A is a circuit diagram showing a main configuration of a high-frequency amplifier having a conventional tank circuit, and FIG. 5B shows a main configuration of an oscillator having a conventional tank circuit similar to Patent Document 1. It is a circuit diagram.

The high-frequency amplifier shown in FIG. 5A includes an npn transistor (hereinafter, simply referred to as “transistor”) Tr0, a tank circuit 11, an input terminal 10, and an output terminal 20.
The base of the transistor Tr0 is connected to the input terminal 10, the collector is connected to one end of the tank circuit 11 and the output terminal 20, and the emitter is connected to the ground. The tank circuit 11 includes a parallel circuit of an inductor Lp0 and a capacitor Cp0, and the other end is connected to a drive voltage input terminal.

  In such a configuration, when the impedance of the tank circuit 11 is Z tank and the current amplification factor of the transistor Tr0 is gm, the voltage gain Av of the high frequency amplifier is

It becomes.

The oscillator shown in FIG. 5B includes tank circuits 11A and 11B, a differential circuit 12, a constant current source CS0, and an output terminal 21.
The differential circuit 12 includes transistors Tr1 and Tr2 whose emitters are connected to each other. This emitter connection point is connected to the ground via a constant current source Cs0. The base of the transistor Tr1 is connected to the collector of the transistor Tr2, and the base of the transistor Tr2 is connected to the collector of the transistor Tr1.

  The tank circuit 11A is composed of a parallel circuit of an inductor Lp1 and a capacitor Cp1, and one end is connected to a connection point between the base of the transistor Tr2 and the collector of the transistor Tr1, and the other end is connected to a drive voltage input terminal. The tank circuit 11B is composed of a parallel circuit of an inductor Lp2 and a capacitor Cp2, and one end is connected to a connection point between the base of the transistor Tr1 and the collector of the transistor Tr2, and the other end is connected to a drive voltage input terminal.

  An output terminal 21 is between a connection point between the base of the transistor Tr2 and the collector of the transistor Tr1 and a connection point between the base of the transistor Tr1 and the collector of the transistor Tr2.

  In such a configuration, assuming that the impedance of the tank circuits 11A and 11B is Z tank and the current of the constant current source is Ibias, the output voltage Vout of the oscillator is

It becomes.

  By the way, in the tank circuit by the parallel circuit of the inductor L and the capacitor C, the Q value becomes high, and it becomes a narrow frequency band characteristic with a steep impedance. However, at present, the high-frequency signal amplifier or oscillator shown in FIG. 5 does not have a steep frequency number characteristic but has a certain frequency bandwidth. As a method of realizing such a wide band, there is a method of inserting a resistor in the tank circuit.

  6A is a circuit diagram of a tank circuit 101A in which a resistor Rp0 is connected in parallel to an inductor Lp0 and a capacitor Cp0. FIG. 6B is a circuit diagram in which a resistor Rs0 is connected in series to an inductor Ls0. It is a circuit diagram of a tank circuit 101B in which a capacitor Cp0 is connected in parallel to an Rs0 series circuit.

  As shown in FIG. 6A, the Q value QtankA of the tank circuit 101A composed of a parallel circuit of an inductor Lp0, a capacitor Cp0, and a resistor Rp0 is

It becomes.

  As shown in FIG. 6B, the Q value QtankB of the tank circuit 101B in which the capacitor Cp0 is connected in parallel to the series circuit of the inductor Ls0 and the resistor Rs0 is

It becomes.
JP 2001-111341 A

  However, in the case of the circuit as shown in FIG. 6A, the impedance ZtankA at the resonance frequency of the tank circuit 101A is

And can be approximated. Therefore, the impedance ZtankA of the tank circuit 101A is proportional to the resistance Rp of the resistor, and the accuracy of the impedance ZtankA is substantially equal to the accuracy of the resistor Rp.

  In the case of a circuit as shown in FIG. 6B, if Qtank is greater than 3, the impedance ZtankB at the resonance frequency of the tank circuit 101B is

And can be approximated. Therefore, the impedance ZtankB of the tank circuit 101B is inversely proportional to the resistance Rs of the resistor, and the accuracy of the impedance ZtankB is substantially equal to the accuracy of the resistor Rs in a range where the error range is not so large (about ± 30%). .

These are shown in FIG.
FIG. 7 is a diagram showing the relationship between the error of the resistor and the error of the equivalent parallel resistance of the tank circuit.

  As shown in FIG. 7, in the configuration of FIG. 6A, when the resistor error increases in the + direction, the equivalent parallel resistance error of the tank circuit also increases in the + direction, and the resistor error increases in the-direction. Then, the error of the equivalent parallel resistance of the tank circuit also increases in the negative direction. 6B, when the resistor error increases in the + direction, the equivalent parallel resistance error of the tank circuit increases in the-direction, and when the resistor error increases in the-direction, the tank circuit equivalent is increased. The error of the parallel resistance increases in the + direction. That is, in any case, if the error of the resistor increases, the error of the equivalent parallel resistance of the tank circuit also increases at a rate approximately equal to this.

  By the way, although the error of the resistor varies depending on the manufacturing method of the resistor, etc., in general specifications, those having an accuracy of about ± 20% are often used. For this reason, the accuracy (error) of the equivalent parallel resistance of the tank circuit is about ± 20%, and the output amplitude of the high-frequency circuit module cannot be made highly accurate. At this time, there is a method of improving the accuracy of the resistor, but the high-precision resistor is expensive and difficult to use for a general-purpose device.

  Accordingly, an object of the present invention is to provide a high-frequency circuit module that can make the output amplitude highly accurate without using a highly accurate resistor or the like even if the operating frequency band is set wide.

  A first resistor connected in series to an inductor in a high-frequency circuit module comprising: a tank circuit in which an inductor and a capacitor are connected in parallel; and a high-frequency circuit that drives using the impedance of the tank circuit as a load; The tank circuit includes a series circuit of the first resistor and the inductor and a second resistor connected in parallel to the capacitor, and a relative ratio between the resistance value of the second resistor and the resistance value of the first resistor is substantially constant. Both resistors are formed so as to become.

  According to the present invention, in a high-frequency circuit module with a tank circuit, comprising: a tank circuit in which an inductor and a capacitor are connected in parallel; and a high-frequency circuit that is driven by using the impedance of the tank circuit as a load. A tank circuit is provided with a first resistor, a series circuit of the first resistor and an inductor, and a second resistor connected in parallel to the capacitor, and the same material is used for the same layer of the same chip. A resistor and a first resistor are formed.

  In this configuration, the second resistor and the first resistor are formed of the same material in the same layer of the same chip, so that the relative ratio between the resistance value of the first resistor and the resistance value of the second resistor is approximately. It becomes constant. Here, the similarity ratio indicates the similarity in the degree and tendency of the resistance value variation of each resistor. The higher the accuracy of the similarity ratio, the more consistent the degree and tendency of each resistor. To do. Therefore, the resistance value fluctuation characteristics of these resistors are substantially the same. When both the resistance values of the first resistor and the second resistor increase in the + direction, the fluctuation of the impedance of the tank circuit by the first resistor becomes the + direction, and the fluctuation of the impedance of the tank circuit by the second resistor. Is in the negative direction. As shown in FIG. 7, these fluctuation amounts are almost the same in the range of about ± 20%, only with the opposite signs. Thereby, these two fluctuation amounts cancel each other, and the fluctuation amount of the impedance of the tank circuit becomes extremely small.

  Further, in the high-frequency circuit module with a tank circuit according to the present invention, the multiplication value of the resistance value of the first resistor and the resistance value of the second resistor of the tank circuit is less than the square value of the impedance of the inductor at the use frequency It is characterized by being set to.

  In this configuration, when the resistance value of the first resistor is R1, the resistance value of the second resistor is R2, the inductance of the inductor is L, and the angular velocity at the center frequency of the operating frequency is ω,

The impedances R1, R2 and inductance L are set in the relationship. As a result, as shown in FIG. 4 to be described later, fluctuations in the impedance (equivalent parallel resistance) of the tank circuit are suppressed.

  The high-frequency circuit module with a tank circuit according to the present invention has a multiplier value of the resistance value of the first resistor and the resistance value of the second resistor and the inductor at the operating frequency when the Q value of the high-frequency circuit is larger than 3. It is characterized in that the relation is set so that the square value of the impedance substantially matches.

  In this configuration, in particular, when the Q value of the high-frequency circuit is larger than 3, the resistance value of the first resistor is R1, the resistance value of the second resistor is R2, the inductance of the inductor is L, and the operating frequency is Assuming that the angular velocity at the center frequency is ω,

The impedances R1, R2 and inductance L are set in the relationship. As a result, as shown in FIG. 4 to be described later, fluctuations in the impedance (equivalent parallel resistance) of the tank circuit are suppressed.

  According to the present invention, a usable frequency band can be widened, and a stable output amplitude can be obtained without substantially changing the equivalent parallel resistance of the tank circuit.

A high-frequency circuit module with a tank circuit according to an embodiment of the present invention will be described with reference to FIGS. In the present embodiment, a high-frequency amplifier will be described as an example of the high-frequency circuit module with a tank circuit.
FIG. 1 is an equivalent circuit diagram of the high-frequency amplifier according to the present embodiment.
As shown in FIG. 1, the high-frequency amplifier includes a tank circuit 1, an npn transistor Tr0, an input terminal 10, an output terminal 20, and a drive voltage input terminal 30.

The base of the transistor Tr0 corresponding to the “high frequency circuit” of the present invention is connected to the input terminal 10, the collector is connected to one end of the tank circuit 11 and the output terminal 20, and the emitter is connected to the ground.
The tank circuit 1 includes a circuit in which an inductor Ls and a first resistor Rs are connected in series, and a capacitor Cp and a second resistor Rp are connected in parallel to the series circuit. One end of the tank circuit 1 is the collector of the transistor Tr0. And the other end is connected to the drive voltage input terminal 30.

  Further, the first resistor Rs and the second resistor Rp are formed so that the relative ratio of the resistance values is substantially constant. For example, the first resistor Rs and the second resistor Rp are manufactured in the same layer of the high frequency module of the same chip with the same material, the same composition, and the same manufacturing process. Thereby, the manufacturing variations and electrical characteristics of the first resistor Rs and the second resistor Rp substantially match.

The tank circuit 1 having such a configuration can be modified as follows in terms of an equivalent circuit.
FIG. 2A is an equivalent circuit diagram in which the series circuit of the inductor Ls and the first resistor Rs of the tank circuit 1 is converted into a parallel circuit of the inductor Lst and the resistor Rpt. FIG. 2B is an equivalent circuit diagram after the resistor Rpt and the second resistor Rp converted in FIG. 2A are combined.

  As shown in FIG. 2A, the series circuit of the inductor Ls and the first resistor Rs of the tank circuit 1 can be replaced with a parallel circuit of the inductor Lst and the first resistor Rpt. At this time, the inductor Lst and the resistor Rpt of the parallel circuit are

It becomes. Furthermore, as shown in FIG. 2B, a resistor Rptt obtained by combining resistors Rpt and Rp is

It becomes.

  FIG. 3 shows corner analysis results of the tank circuit 1 of the present embodiment and the above-described conventional tank circuits 101A and 101B. FIG. 3A shows the conventional tank circuit 101A, and FIG. In the case of the tank circuit 101B, FIG. 3C shows the case of the tank circuit 1 of the present embodiment. In FIG. 3, the Rmax curve shows a case where the element values of the circuit elements constituting the tank circuit are all shifted in the increasing direction, and the Rmin curve is the element value of each circuit element constituting the tank circuit. The case where it deviates in the direction which becomes small is shown. The Rtyp curve indicates a case where the element value of each circuit element constituting the tank circuit is a standard value.

  As shown in FIG. 3, the tank circuit 101A and 101B in FIGS. 3A and 3B corresponding to the conventional example has a maximum impedance variation of 2 dB or more, whereas in the tank circuit 1 of the present embodiment, Impedance variation hardly occurs. Thus, by using the tank circuit 1 of the present embodiment, the frequency characteristics of the impedance of the tank circuit are the same without being affected by variations in circuit elements constituting the tank circuit.

  As a result, a high-frequency amplifier having stable output characteristics can be configured.

  By the way, the first resistor Rs, the second resistor Rp, and the inductor Ls are set so that the following relationship is established. Note that ω is a use frequency (resonance frequency of the tank circuit 1).

  In this case, the Q value Qtank of the tank circuit 1 is

It becomes.

  Also,

  And

  Here, when the Q value Qtank of the tank circuit 1 and the relationship of Expression 11 are changed, changes in the impedance of the tank circuit 1 due to errors of the resistors Rs and Rp are shown in FIG.

FIG. 4 is a diagram showing a result of simulating changes in the impedance of the tank circuit 1 due to errors in the resistors Rs and Rp when the Q value Qtank of the tank circuit 1 and the relationship of Expression 11 are changed. .
4A, the Q value Qtank is 3, and the multiplication value of the resistors Rs and Rp (the left side of Expression 11) is 0 with respect to the square value of the impedance of the inductor Ls (the right side of Expression 11). It shows the case where it changed from 7 times to 1.3 times.
FIG. 4B shows a case where the Q value Qtank is 2, and the multiplication value of the resistors Rs and Rp changes from 0.7 times to 1.3 times the square value of the impedance of the inductor Ls. Indicates.
In FIG. 4C, the Q value Qtank is 1.5, and the multiplication value of the resistors Rs and Rp changes from 0.6 times to 1.0 times the square value of the impedance of the inductor Ls. Shows the case.
In FIG. 4D, the Q value Qtank is 1.0, and the multiplication value of the resistors Rs and Rp changes from 0.4 times to 1.0 times the square value of the impedance of the inductor Ls. Shows the case.
When the Q value of the tank circuit 1 is set to 3, by setting the first resistor Rs, the second resistor Rp, and the inductor Ls so as to satisfy the relationship of Equation 11, FIG. As shown, even if the errors of the resistors Rs and Rp are ± 20%, the impedance of the tank circuit falls within the range of about 3%.
When the Q value of the tank circuit 1 is set to 2, the multiplication value of the resistors Rs and Rp is about 0.85 times the relationship of the square value of the impedance of the inductor Ls (relationship of Expression 13). In addition, by setting the first resistor Rs, the second resistor Rp, and the inductor Ls, as shown in FIG. 4B, even if the errors of the resistors Rs and Rp are ± 20%, The impedance of the tank circuit 1 falls within a range of about 2%.
When the Q value of the tank circuit 1 is set to 1.5, the multiplication value of the resistors Rs and Rp is about 0.7 times the square value of the impedance of the inductor Ls (relationship of Expression 13). As shown in FIG. 4C, by setting the first resistor Rs, the second resistor Rp, and the inductor Ls, the errors of the resistors Rs and Rp are ± 20%. However, the impedance of the tank circuit 1 falls within a range of about 1%.
Further, when the Q value of the tank circuit 1 is set to 1, the multiplication value of the resistors Rs and Rp is about 0.55 times the relation of the square value of the impedance of the inductor Ls (relationship of Expression 13). In addition, by setting the first resistor Rs, the second resistor Rp, and the inductor Ls, as shown in FIG. 4D, even if the errors of the resistors Rs and Rp are ± 20%, The impedance of the tank circuit 1 falls within a range of about 3%.
Thus, if the Q value is 3, the resistance values of the resistors Rs and Rp are set by setting the first resistor Rs, the second resistor Rp, and the inductor Ls according to the relationship of Expression 11. The variation in the impedance of the tank circuit 1 due to an error can be suppressed to an extremely small state. Even when the Q value is larger than 3, by satisfying Expression 11, the variation in impedance of the tank circuit 1 can be suppressed. Further, even when the Q value is smaller than 3, the first resistor Rs, the second resistor Rp, and the inductor Ls are set to appropriate values according to the relationship of Expression 13, so that each resistor Rs, Rp The variation in impedance of the tank circuit 1 due to the resistance value error can be suppressed to an extremely small state.

  Thereby, a high-frequency amplifier having a stable output can be configured.

  In this embodiment, the high-frequency amplifier has been described as an example. However, the above-described configuration is also applied to other high-frequency circuit modules that include a tank circuit and whose operating characteristics are determined based on the impedance of the tank circuit. And the above-described effects can be achieved. For example, in the case of a high-frequency oscillator as shown in FIG. 5B, each tank circuit 11A, 11B may be configured similarly to the tank circuit 1 of the present embodiment. That is, in the tank circuit 11A, a first resistor is connected in series to the inductor Lp1, and a second resistor is connected in parallel to the series circuit. The first resistor and the second resistor are formed of the same material on the same layer of the same chip. Further, in the tank circuit 11B, a third resistor is connected in series to the inductor Lp2, and a fourth resistor is connected in parallel to this series circuit. The third resistor and the fourth resistor are formed of the same material on the same layer of the same chip. Then, the first resistor and the third resistor are set to the same resistance value, and the second resistor and the fourth resistor are set to the same resistance value.

It is an equivalent circuit diagram of the high frequency amplifier of the embodiment of the present invention. An equivalent circuit diagram in which the series circuit of the inductor Ls and the first resistor Rs of the tank circuit 1 is converted into a parallel circuit of the inductor Lst and the resistor Rpt, and the resistor Rpt and the first resistor converted in FIG. It is an equivalent circuit diagram after combining the two resistors Rp. It is a corner analysis result of the tank circuit 1 of the present embodiment and the above-described conventional tank circuits 101A and 101B. It is a figure showing the result of having simulated the change of the impedance of the tank circuit 1 by the error of each resistor Rs and Rp in the case of changing the Q value Qtank of the tank circuit 1 and the relationship of Formula 11. 2 is a circuit diagram showing a main configuration of a high-frequency amplifier including a conventional tank circuit, and a circuit diagram showing a main configuration of an oscillator including a conventional tank circuit similar to Patent Document 1. FIG. A circuit diagram of a tank circuit 101A in which a resistor Rp0 is connected in parallel to an inductor Lp0 and a capacitor Cp0, and a tank circuit in which a resistor Rs0 is connected in series to an inductor Ls0 and a capacitor Cp0 is connected in parallel to the Ls0 and Rs0 series circuit It is a circuit diagram of 101B. It is a figure which shows the relationship between the error of a resistor, and the error of the equivalent parallel resistance of a tank circuit.

Explanation of symbols

  1, 11, 11A, 11B-tank circuit, 10-input terminal, 12-differential circuit, 20, 21-output terminal, 30-drive voltage input terminal

Claims (4)

A tank circuit in which an inductor and a capacitor are connected in parallel;
A high frequency circuit for driving the impedance of the tank circuit as a load;
In a high-frequency circuit module with a tank circuit equipped with
The tank circuit includes a first resistor connected in series to the inductor, a series circuit of the first resistor and the inductor, and a second resistor connected in parallel to the capacitor,
A high frequency circuit module with a tank circuit, wherein both resistors are formed such that a relative ratio between a resistance value of the second resistor and a resistance value of the first resistor is substantially constant. A tank circuit in which an inductor and a capacitor are connected in parallel;
A high frequency circuit for driving the impedance of the tank circuit as a load;
In a high-frequency circuit module with a tank circuit equipped with
The tank circuit includes a first resistor connected in series to the inductor, a series circuit of the first resistor and the inductor, and a second resistor connected in parallel to the capacitor,
The high frequency circuit module with a tank circuit, wherein the second resistor and the first resistor are formed using the same material in the same layer of the same chip.   The multiplication value of the resistance value of the first resistor and the resistance value of the second resistor is set to a relationship that is less than or equal to the square value of the impedance of the inductor at a use frequency. High frequency circuit module with tank circuit. When the Q value of the high frequency circuit is larger than 3,
4. The tank circuit according to claim 3, wherein a multiplier of the resistance value of the first resistor and the resistance value of the second resistor and the square of the impedance of the inductor at the operating frequency are set to substantially coincide with each other. A high-frequency circuit module.

Images