JP4417666B2 - Group delay time adjuster - Google Patents

Description

  The present invention relates to a group delay time adjuster used in, for example, a feedforward type distortion compensation device, and more particularly, to an electric group delay time between input and output in an application where a good group delay characteristic is required. The present invention relates to a group delay time adjuster that can be controlled automatically.

In an apparatus that transmits signals of various frequencies at once, it is necessary to design in consideration of group delay characteristics.
Conventionally, in applications that require group delay characteristics, a device that adjusts the group delay time by mechanically changing the propagation time, such as a coaxial plunger, has been generally used.
The group delay characteristic is a characteristic in which the phase of the signal passing through it is delayed in proportion to the frequency (the phase rotates in the negative direction as the frequency increases). In a circuit with only a group delay but no phase change It is characterized by no change in waveform.

  An object of the present invention is to provide a group delay time adjuster that can electrically control a delay time in an application that requires a group delay characteristic.

  The group delay time adjuster of the present invention for solving the above-described problem is a first element to which a predetermined signal is transmitted, a reactance value is fixed, and a reactance value changes according to a voltage value of an applied voltage. The two second elements have a transmission line connected in series or shunt and a voltage input terminal for supplying the same voltage to the two second elements, and are supplied from the voltage input terminals. A resonant circuit constituted by the first element and the two second elements, based on the reactance value of the two second elements determined according to the voltage value of the voltage, while maintaining the input loss at a predetermined value or less. Q is changed, whereby the group delay time of the signal passing through the transmission line is changed.

  Since the load Q is changed while keeping the input loss at a predetermined value or less, preferably approximately “0”, the group delay time can be changed. The group delay time varies depending on the reactance value of the second element. At this time, in order to make the reactance values of the two second elements equal, the same voltage value is applied, so that the control becomes simple.

  In such a group delay time adjuster, for example, the first element is connected in series to the transmission line, and the two second elements sandwich the first element. The first element is connected to the shunt with respect to the transmission line, and the two second elements are connected to the shunt. A so-called T-shape can be configured in which the connection point with the transmission line is sandwiched in series with respect to the transmission line. In any case, since the two second elements have the same reactance value, the control is simple.

  In another group delay time adjuster of the present invention, a predetermined signal is transmitted, a first element having a fixed reactance value, and two second reactance values that change in accordance with a voltage value of an applied voltage. Group delay time adjusting means having a transmission line in which elements are connected in series or shunt and a voltage input terminal for supplying the same voltage to the two second elements, so that the transmission line is in series The group delay time adjusting means is connected to the first element and the second element according to reactance values of the two second elements determined according to the voltage value of the voltage supplied from the voltage input terminal. A resonance circuit composed of a plurality of second elements is configured such that the load Q changes while keeping the input loss below a predetermined value, thereby changing the group delay time of the signal passing through the transmission line. .

  ADVANTAGE OF THE INVENTION According to this invention, the group delay time regulator which can change a group delay time electrically by simple control can be provided.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a group delay time adjuster according to a first embodiment of the present invention.
The group delay time adjuster is connected to a transmission line 1 for transmitting a signal input from the input side to the output side, an inductive element L1 connected in series to the transmission line 1, and a shunt. Variable capacitance elements C1 and C2. The variable capacitance elements C1 and C2 are provided at positions sandwiching the induction element L1. The variable capacitance elements C1 and C2 have the same characteristics, and take the same capacitance value by the voltage V1 applied from the outside by the voltage input terminal. Naturally, when the voltage V1 changes, the capacitance values of the variable capacitance elements C1 and C2 change in the same way.

  When the group delay time adjuster having such a configuration is considered on the Smith chart, an inductive value and a capacitance value whose impedance value starts from “1” and returns to the original “1” at a specific frequency are obtained. You can choose. At this specific frequency, the insertion loss of the resonance circuit constituted by the induction element L1 and the variable capacitance elements C1 and C2 is “0”. At frequencies before and after that, the impedance value does not return to “1”, a mismatch occurs, and an insertion loss occurs. That is, it becomes a band pass characteristic.

When the impedance value of the inductive element L1 is set to a value close to the impedance value of the transmission line 1, and the susceptance values of the variable capacitance elements C1 and C2 are set to values before and after the susceptance value of the transmission line, the impedance value on the Smith chart is specified. Return to the original “1” at the frequency of. Details of the explanation using the Smith chart will be described later.
Even if the susceptance values of the variable capacitance elements C1 and C2 are changed before and after the susceptance value of the transmission line 1, the insertion loss at the frequency is almost “0”. However, since the load Q changes, the group delay time for signals around this frequency can be changed. Since the capacitance values of the variable capacitance elements C1 and C2 may be equal, the capacitance value can be easily changed.

In the group delay time adjuster of FIG. 1, when the induction value of the inductive element L1 is “79.58 nH” and the frequency is 100 MHz +/− 2 MHz, the group value is set when the capacitance values of the variable capacitance elements C1 and C2 are “28.6 pF”. When the delay time is “2.86 ns” and the capacitance value is “31.83 pF”, the group delay time is “3.15 ns”. The insertion loss at this time is all “0.002 dB” or less. The frequency range is determined by the allowable group delay time and the allowable insertion loss.
When group delay is calculated under the condition that the absolute value of the impedance value of the capacitive element and the impedance value of the inductive element is close to the transmission line impedance, the group delay time is proportional to the impedance value of the capacitive element.

The group delay time of the group delay time adjuster of the first embodiment is mathematically analyzed. FIG. 2 is a circuit diagram for explanation, in which a load impedance 2 and a power supply output impedance 3 are added to the group delay time adjuster of FIG.
The transmission line 1, the inductive element L1, the load impedance 2, the impedance value of the power supply output impedance 3, etc. are all normalized to “1”. The frequency is also normalized to “1”. The admittance values of the variable capacitance elements C1 and C2 are assumed to be jm (≈j1).
A voltage transfer function is obtained by calculating backward from the power supply voltage for the voltage V2 applied to the load impedance 2 to be "1".

1) When the frequency is 1 +/− Δ, the admittance Y (C) of the variable capacitance element C2 is jm (1 +/− Δ). Since the voltage V2 applied to the load impedance 2 is “1”, the total current I (Z2) of the current flowing through the load impedance 2 and the current flowing through the variable capacitor C2 connected in parallel thereto is
I (Z2) = 1 + jm (1 +/− Δ)
It is represented by Here, Z2 represents the combined impedance of the load impedance 2 and the variable capacitance element C2.

2) When the frequency is 1 +/− Δ, the impedance Z (L) of the inductive element L1 is j (1 +/− Δ), and the current flowing through the inductive element L1 is I (Z2). The voltage V1 applied to the element C1 is
V1 = V2 + Z (L) * I (Z2)
= 1 + j (1 +/− Δ) * {1 + jm (1 +/− Δ)}
= 1 + j (1 +/− Δ) −m (1 +/− Δ) (1 +/− Δ)
= 1−m − / + 2Δm + j (1 +/− Δ)
+/- and-/ + are represented by frequency deviation +/-.

3) The current I (C1) flowing through the variable capacitor C1 is
I (C1) = V1 * Y (C)
= {1-m − / + 2Δm + j (1 +/− Δ)} * jm (1 +/− Δ)
= −m (1 +/− Δ) ² + j (1−m − / + 2Δm) m (1 +/− Δ)
= −m − / + 2Δm + jm {1-m +/− (1-3m) Δ}
It is represented by

4) The total current I (Z1) flowing through the variable capacitance element C1 and the induction element L1 is
I (Z1) = I (Z2) + I (C1)
= 1−m − / + 2Δm + jm {2-m +/− (2−3m) Δ}
It is represented by

5) The voltage generated at the power supply output impedance 3 is equal to I (Z1) because the power supply output impedance 3 is normalized. Therefore, the power supply voltage Vo is
Vo = I (Z1) + V1
= 2-2m − / + 4Δm + j {1 + 2m−m ² +/− (1 + 2m−3m ² ) Δ}
It is represented by
Vo ′ obtained by rotating this vector by −90 degrees is
Vo ′ = (1 + 2m−m ² +/− (1 + 2m−3m ² ) Δ) −2j (1−m − / + 2Δm)
It is represented by

Since the transfer function H is 2 / Vo and GD is -d (∠H) / dω,
GD = -d (∠H) / dω
= D (∠Vo ′) / dΔ
∠ Vo ′ = tan ⁻¹ (2m−2 +/− 4Δm) / (1 + 2m−m ² +/− (1 + 2m−3m ² ) Δ)
Here, if m≈1 and Δ << 1,
∠Vo'≈tan ^-1 (-2 (1-m-/ + 2Δm) / 2)
It is expressed. Therefore,
∠Vo '=-(1-m-+ /-2Δm)
GD = d (∠Vo ′) / dΔ
= + /-2m
It becomes.

From the above calculation results, when m≈1, the GD near the center frequency is proportional to m. That is, the group delay time of this group delay time adjuster is proportional to the capacitance values of the variable capacitance elements C1 and C2.
In the above analysis, the frequency is normalized. For example, when m = 1 and the frequency is 100 MHz, ω = 628 Mr / s, and the group delay time is GD = 2 / ω = 3.18 ns.

FIG. 3 shows a group delay time adjuster according to the second embodiment of the present invention.
The group delay time adjuster is connected to a transmission line 1 for transmitting a signal input from the input side to the output side, a capacitive element C3 connected in series to the transmission line 1, and a shunt. Variable induction elements L2 and L3. The variable induction elements L2 and L3 are provided at positions sandwiching the capacitive element C3. The variable induction elements L2 and L3 have the same characteristics, and take the same induction value by the voltage V1 applied from the outside by the voltage input terminal. Naturally, when the voltage V1 changes, the induction values of the variable induction elements L2 and L3 change in the same way.

FIG. 4 shows a group delay time adjuster according to the third embodiment of the present invention.
The group delay time adjuster includes a transmission line 1 for transmitting a signal input from the input side to the output side, variable capacitance elements C4 and C5 connected in series to the transmission line 1, and a shunt. And an inductive element L4 connected to the. The induction element L4 is provided between the variable capacitance elements C4 and C5. The variable capacitance elements C4 and C5 have the same characteristics, and take the same capacitance value by the voltage V1 applied from the outside by the voltage input terminal. Naturally, when the voltage V1 changes, the capacitance values of the variable capacitance elements C4 and C5 change in the same way.

FIG. 5 shows a group delay time adjuster according to the fourth embodiment of the present invention.
The group delay time adjuster includes a transmission line 1 for transmitting a signal input from the input side to the output side, variable induction elements L5 and L6 connected in series to the transmission line 1, and a shunt. And a capacitive element C6 connected to the capacitor. The capacitive element C6 is provided between the variable induction elements L5 and L6. The variable induction elements L5 and L6 have the same characteristics, and take the same induction value by the voltage V1 applied from the outside by the voltage input terminal. Naturally, when the voltage V1 changes, the induction values of the variable induction elements L5 and L6 change in the same way.

  For the group delay time adjusters of the second to fourth embodiments, a description of specific numerical values is omitted, but only the polarity of the imaginary number is reversed from that of the group delay time adjusters of the first embodiment. Since the induction value of the two variable induction elements or the capacitance value of the two variable capacitance elements can always be the same value, the insertion loss is hardly changed, and only the group delay time can be changed.

The frequency characteristics of the group delay time adjuster of this embodiment will be described using the Smith charts of FIGS.
FIG. 6 is a plot of impedance values as viewed on the load (output) side at points A to D of the group delay time adjuster of the first embodiment on a Smith chart. In FIG. 6, the impedance when the load (output) side is viewed from the point A is at the center on the Smith chart.

  The point B is a point when the admittance of the variable capacitance element C2 is added to the point A. When the frequency is high, the admittance of the variable capacitance element C2 also becomes large. Therefore, the constant conductor circle advances farther from the center of the Smith chart than the point B, and when the frequency is low, the constant conductor circle moves from the point B to the center of the Smith chart. It only goes near.

  The point C is a point when the admittance of the induction element L1 is added to the point B. When the frequency is high, the impedance of the inductive element L1 also increases. Therefore, the constant resistance circle advances farther from the center of the Smith chart than the C point, and when the frequency is low, the constant resistance circle is closer to the Smith chart center than the C point. It only goes to.

The point D is a point when the admittance of the variable capacitance element C1 is added to the point C. When the frequency is high, it proceeds greatly on the constant conductor circle, so that the amount of the large advancement by the first variable capacitance element C2 is recovered and it is on the real axis of the chart. Its impedance is greater than “1”. When the frequency is low, the impedance is smaller than “1”.
When this circuit is passed again, the frequency characteristics are restored. Thus, for example, the frequency range (bandwidth) is widened when the insertion loss is below a certain value.

FIG. 7 is a plot of impedance values as viewed on the load (output) side at points A and E to G of the group delay time adjuster of the fourth embodiment on a Smith chart.
Also in FIG. 7, as in FIG. 6, impedance changes due to the variable induction elements L <b> 5 and L <b> 6 and the capacitive element C <b> 6 are represented by points A, E, F, and G. As a result, the frequency characteristic comes to a position where the impedance is smaller than 1 when the frequency is high, and to a place where the impedance is larger than 1 when the frequency is low. When this circuit is also passed through in the same manner as in FIG. 6, the frequency characteristics are restored and the frequency range is expanded.

  Since the frequency characteristics of both FIGS. 6 and 7 are opposite to each other, if two stages are connected in cascade, they are further complemented, so that the usable frequency range is expanded.

  A so-called varicap can be used for the variable capacitance elements C1, C2, C4, and C5, and a coil wound around a core whose permeability is changed by a change in the external magnetic field can be used for the variable induction elements L2, L3, L5, and L6. . Thereby, the capacitance values of the variable capacitance elements C1, C2, C4, and C5 and the induction values of the variable induction elements L2, L3, L5, and L6 can be easily changed electrically.

  The group delay time adjusters of the first to fourth embodiments as described above may be connected in multiple stages. Thereby, the delay amount can be increased in the same frequency band. In addition, it becomes possible to supplement the frequency characteristics. Furthermore, the wide band group delay time can be made variable. In multi-stage connection, it is possible to obtain desired characteristics by inserting an attenuator or an isolator between the group delay time adjusters.

The circuit diagram of the group delay time regulator of 1st Embodiment. Explanatory drawing for analyzing the group delay time regulator of 1st Embodiment mathematically. The circuit diagram of the group delay time regulator of 2nd Embodiment. The circuit diagram of the group delay time regulator of 3rd Embodiment. The circuit diagram of the group delay time regulator of 4th Embodiment. FIG. 3 is an exemplary diagram of a Smith chart of a group delay time adjuster according to the first embodiment. FIG. 10 is an exemplary Smith chart of a group delay time adjuster according to a fourth embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Transmission line 2 Load impedance 3 Power supply output impedance C1, C2, C4, C5 Variable capacitive element C3, C6 Capacitance element L1, L4 Inductive element L2, L3, L5, L6 Variable inductive element

Claims (2)

A first element to which a predetermined signal is transmitted and a reactance value composed of a capacitive element connected in series or an inductive element connected to a shunt is fixed, and when the first element is the capacitive element, connected to the shunt When the first element is the inductive element, the first inductive element is composed of a variable capacitance element connected in series. The reactance value is variable, and the two second inductive elements are provided between the first element . A transmission line having two elements;
And a voltage input terminal for the same supplied reactance value of each of the second element of the same voltage to each of said two second elements,
The reactance value of the two second elements determined according to a voltage value of the voltage supplied from the voltage input terminal, the group delay time of the signal passing through the pre-Symbol transmission line is configured to vary ,
Group delay time adjuster. When a predetermined signal is transmitted , a first element having a fixed reactance value including a capacitive element connected in series or an inductive element connected to a shunt is provided, and when the first element is the capacitive element In the case where the variable inductive element connected to the shunt and the first element is the inductive element, the reactance value composed of the variable capacitive element connected in series is variable, and the two second inductive elements are provided at positions sandwiching the first element . group delay time adjusting means having a transmission line having two elements, and a voltage input terminal for the same reactance value of the two second each respective second element by supplying the same voltage of the device A plurality of the transmission lines are connected in series,
Each group delay time adjusting means, the reactance value of each of said two second elements determined according to a voltage value of the voltage supplied from the voltage input terminal, the group delay of the signal passing through the pre-Symbol transmission line Configured to change time,
Group delay time adjuster.

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