JP2003197433A - Transmission line transformer and amplification unit using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a transmission line transformer which enables surface mounting by winding a wire on a binocular core. <P>SOLUTION: In the transmission line transformer, a balanced-to-unbalanced transformer 42, whereon a wiring is wound to give the impedance ratio of 1:1 is connected to impedance conversion transformers 40, 41 whereon a wiring, is wound to impedance ratio of 9:4, a balanced-to-unbalanced transformer, whose impedance ratio is 2:1 is constituted and each of the wirings is wound on a binocular core 51. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transmission line transformer used in a wide band amplification circuit for stably amplifying an input signal of a CATV or the like with a high gain over a multi-channel wide band and an amplification unit using the same.

[0002]

2. Description of the Related Art In CATV and the like, the number of video signal channels tends to increase more and more. By the way, the bandwidth per channel of the video signal channel is about 6 MH.
z. Therefore, for example, if there are more than 100 video channels in some countries, at least 60
It is necessary to amplify the input signal with high gain without distortion over the band of 0 MHz.

Conventionally, in consideration of impedance matching and the like, a wide band amplifier circuit uses transformers in front and rear stages, and many capacitors or resistors are used to form a negative feedback circuit.

Since it is difficult to integrate the transformer or the capacitor, a hybrid IC system is used in which a transformer and a capacitor are provided on a ceramic substrate, a chip including a transistor is attached, and these are connected to form a wide band amplifier circuit. ing.

FIG. 1 is a circuit diagram of an amplification unit. An input transformer 1 in which a high-frequency input signal is applied to an input side primary winding, an output transformer 2 in which an output signal is taken out from an output side secondary winding, and a secondary side winding of the input transformer 1. The output transformer 2 comprises a first amplifier circuit 3 and a second amplifier circuit 4 connected in a push-pull manner between the primary windings.

In the first amplifier circuit 3, each gate electrode is connected between the secondary windings of the input transformer 1, and the resistor 5
FET6 and FET in which each source electrode is coupled through
It consists of 7. A feedback circuit 1 including resistors 8 and 9 and capacitors 10 and 11 between the drain electrode and the gate electrode of the FET 6 and the FET 7 which constitute the first amplifier circuit 3, respectively.
3, 14 are connected.

The second amplifier circuit 4 comprises upper FETs 16 and 17 and lower FETs 18 and 19 connected in cascode. The gate electrode of the upper FET 16 is connected to the drain electrode of the FET 6 of the first amplifier circuit 3 via the capacitor 20. Similarly, the gate electrode of the lower FET 18 is connected to the drain electrode of the FET 7 of the first amplifier circuit 3 via the capacitor 21.

In the first amplifying circuit 3 and the second amplifying circuit 4, the high frequency signal applied to the input transformer 1 is fed from both ends of the secondary winding of the input transformer 1 to the F of the first amplifying circuit 3.
It is added to the gate electrodes of ET6 and FET7 and amplified by grounding the source. The high-frequency signal amplified by the source grounding is applied to the gates of the FET 16 and the FET 18 of the second amplifier circuit 4 and also to the feedback circuit 13 and the feedback circuit 14,
Negative feedback is given.

The high-frequency signals applied to the gates of the FET 16 and the FET 18 are source-grounded and amplified.
It is added to 17 and FET 19 and amplified by grounded gate. The high-frequency signal, whose gate is grounded and amplified by the FET 17 and the FET 19, is applied to the output transformer 2, and the output signal is taken out from the output transformer 2.

[0010]

As described above, the high frequency signal input to the input transformer 1 is amplified by the first amplifying circuit 3 and the second amplifying circuit 4 and taken out from the secondary winding of the output transformer 2. To be done. By the way, the first amplifying circuit 3 and the second amplifying circuit 4 are push-pull connected, but since the output signal taken out from the output transformer 2 is added to the unbalanced output transmission line, the output transformer 2 is balanced- Must be an unbalanced transformer. Further, since the output impedance of the second amplifier circuit 4 is 300Ω and the output transmission line is 75Ω, it is necessary to match the impedance.

FIG. 10 shows a conventional output transformer in which a primary winding 32 and a secondary winding 33 are wound around a donut-shaped toroidal core 31.

As shown in FIG. 11, the primary winding 32
Is the number of turns of the winding 32a above the midpoint 34 is n1 = 4, the number of turns of the lower winding 32b is n2 = 4, and the secondary side winding 3 is
When the number of turns of 3 is n3 = 6, the impedance a of the primary winding 32 and the impedance b of the secondary winding 33 are a: b = 64: 36 about 2: 1 for impedance matching.

In order to satisfy such conditions, a toroidal core is conventionally used and a balanced-unbalanced transformer having an impedance ratio of 2: 1 is used as an output transformer. However, since the balanced-unbalanced transformer using the toroidal core cannot be surface-mounted, the mounting had to be done by a worker.

[0014]

According to the present invention, a balanced-unbalanced transformer wound to have an impedance ratio of 1: 1 is connected to an impedance conversion transformer wound to have an impedance ratio of 9: 4. A balanced-unbalanced transmission line transformer having an impedance ratio of 2: 1 is provided.

The present invention also provides a transmission line transformer in which each of the windings is wound around a binocular type core.

Further, according to the present invention, an impedance conversion transformer wound so as to have an impedance ratio of 9: 4 is connected to each output terminal of a push-pull connected broadband amplifier circuit, and the impedance conversion transformer is connected to the impedance conversion transformer. Connect a balanced-unbalanced transformer wound so that the ratio is 1: 1 and the impedance ratio is 2: 1.
A transmission line transformer having the above structure, and an unbalanced transmission line connected to the output side winding of the constructed transmission line transformer, and an amplification unit using the same are provided.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A transmission line transformer of the present invention and an amplification unit using the same will be described with reference to FIGS.

FIG. 1 is a circuit diagram of an amplifier unit using the transmission line transformer of the present invention. As described above, the input transformer 1 in which a high-frequency input signal is applied to the input-side primary winding of the input transformer 1, the output transformer 2 in which an output signal is taken out from the output-side secondary winding, and the input It comprises a first amplification circuit 3 and a second amplification circuit 4 connected in a push-pull form between the secondary winding of the transformer 1 and the primary winding of the output transformer 2.

In the first amplifier circuit 3, each gate electrode is connected between the secondary windings of the input transformer 1, and the resistor 5
FET6 and FET in which each source electrode is coupled through
It consists of 7. A feedback circuit 1 including resistors 8 and 9 and capacitors 10 and 11 between the drain electrode and the gate electrode of the FET 6 and the FET 7 which constitute the first amplifier circuit 3, respectively.
3, 14 are connected.

The second amplifier circuit 4 comprises upper FETs 16 and 17 and lower FETs 18 and 19 connected in cascode. The gate electrode of the upper FET 16 is connected to the drain electrode of the FET 6 of the first amplifier circuit 3 via the capacitor 20. Similarly, the gate electrode of the lower FET 18 is connected to the drain electrode of the FET 7 of the first amplifier circuit 3 via the capacitor 21.

The source electrodes of the FET 16 and the FET 18 are connected via a resistor 22, and the FET 17 and the FE are connected.
The gate electrode of T19 is connected via a resistor 23 to form a push-pull amplifier circuit.

Upper FET constituting the second amplifier circuit
A feedback circuit 26 including a resistor 24 and a capacitor 25 is connected between the gate electrode of 16 and the drain electrode of the FET 17. Gate electrode of lower FET 18 and FET 1
A feedback circuit 29 composed of a resistor 27 and a capacitor 28 is connected between the drain electrodes of 9.

The resistors 5 and 22 virtually ground the FETs 6 and 7 and the FETs 16 and 18 by these resistors, and remove the secondary distortion due to variations in the characteristics of these FETs. The resistor 23 supplies a bias voltage to the gate electrodes of the FETs 17 and 19 to stabilize the operation of grounding the gate.

In the first amplifier circuit 3 and the second amplifier circuit 4, the high frequency signal applied to the input transformer 1 is fed from both ends of the secondary winding of the input transformer 1 to the F of the first amplifier circuit 3.
It is added to the gate electrodes of ET6 and FET7 and amplified by grounding the source. The high-frequency signal amplified by the source grounding is applied to the gates of the FET 16 and the FET 18 of the second amplifier circuit 4 and also to the feedback circuit 13 and the feedback circuit 14,
Negative feedback is given.

The high frequency signals applied to the gates of the FET 16 and the FET 18 are source-grounded and amplified, and the FETs are respectively grounded.
It is added to 17 and FET 19 and amplified by grounded gate. The high-frequency signal whose gate is grounded and amplified by the FET 17 and the FET 19 is applied to the output transformer 2, and the output signal is taken out from the secondary side of the output transformer 2.

The high-frequency signal, which is amplified by the FET 17 and the FET 19 and grounded at the gate, is fed back to the feedback circuit 26 and the feedback circuit 2.
Negative feedback is made by joining 9. Source electrodes of the FET 6 and the FET 7 are connected via a resistor 5, and they virtually operate as a source-grounded push-pull amplifier to cancel out secondary distortions generated in them.

Similarly, the FETs 16 and 18 have source electrodes connected through a resistor 22 and virtually operate as push-pull amplifiers whose sources are grounded.
The gates of 7 and FET 19 are connected via a resistor 23, and operate virtually as a grounded push-pull amplifier.

FIG. 2 is a model view of the transmission line transformer of the present invention used for the output transformer 2. The transmission line transformer has two impedance conversion transformers 40 each having a winding wound so that the impedance ratio is 9: 4.
A balanced-unbalanced transformer 43, in which a winding is wound to have an impedance ratio of 1: 1, is connected to 41 to form a balanced-unbalanced transformer having an impedance ratio of 2: 1 as a whole.

FIG. 3 shows the impedance conversion transformer 4
In the winding diagram shown by the winding No. 0, it has a first winding 45, a second winding 46 and a third winding 47.

Similarly, FIG. 4 is a winding diagram showing the windings of the impedance conversion transformer 41. The first winding 48 and the second winding
Winding 49 and third winding 50.

FIG. 5 shows the impedance conversion transformer 4
It is an appearance model drawing of 0 and 41, and is a binoculars type core 51.
And a substrate 52 having terminals W, X, Y, and Z.

6 and 7 show the binocular type core 51.
The first winding wire 45, the second winding wire 46 and the third winding wire 47 are wound around the first cylindrical hole 53, and the first winding wire 48 and the second winding wire are wound around the hole 54. It is the side view which wound 49 and the 3rd winding 50.

The first and second third windings 45 to 50 are all wound with the same number of turns, which is three in the case of FIGS. Further, the impedance realized by the three first, second, and third windings 45, 46, and 47, the first winding 45, and the third winding 4
The ratio of the impedances realized by the two windings of 7 is proportional to the square of the number of turns of each, and thus becomes 9: 4. The same applies to the first, second, and third windings 48, 49, and 50.

One end of the impedance conversion transformer 40 is connected to the first winding 45 and the second winding 46 of the terminal W, and the other end of the second winding 46 is connected to the terminal X. . One end of the impedance conversion transformer 41 is connected to the first winding 48 and the second winding 49 of the terminal Y, and the other end of the second winding 49 is connected to the terminal Z.

The impedance conversion transformers 40, 4
The terminals W and Y of 1 are balanced-unbalanced transformers 43 in which an impedance ratio is wound around the binoculars type core at a ratio of 1: 1.
Each of them is connected to the primary side winding of each of them to form a balanced-unbalanced transmission line transformer which is wound with an impedance ratio of 2: 1 as a whole.

FIG. 8 is a load characteristic diagram of the transmission line transformer of the present invention. As described above, the high frequency signal input to the input transformer 1 is amplified by the first amplifier circuit 3 and the second amplifier circuit 4, and is transmitted to the unbalanced load line via the above-mentioned transmission line transformer. Since the balanced-unbalanced transformer 43 is connected to the impedance conversion transformers 40 and 41, the transmission line transformer of the present invention becomes the load line X, and the drain voltage does not exceed the withstand voltage even if the signal amplitude is increased.

If only a balanced-unbalanced transformer formed by winding it around the binoculars type core 51 at a ratio of 4: 1 without using an impedance conversion transformer is used as the output transformer, the load line Y results. The load line X
The slope becomes gentler than. Therefore, if the drain voltage of the FET is increased, the breakdown voltage will be exceeded. However, in the transmission line transformer of the present invention, the impedance conversion transformer 40,
Since the balanced-unbalanced transformer 43 is connected to 41, it becomes the load line X, and the drain voltage does not exceed the withstand voltage even if the signal amplitude is increased.

FIG. 9 is a pass characteristic diagram of an amplification unit using the transmission line transformer of the present invention. The output signal that is passed is -3.3343 Db at 49.5436 MHz, 10
-3.3569 Db, 866.47 at 0.207 MHz
It can be passed at -5.0777 dB at 8 MHz with little attenuation.

[0039]

According to the present invention, the unbalanced transformer wound so that the impedance ratio becomes 1: 1 is connected to the impedance conversion transformer wound so that the impedance ratio becomes 9: 4. Equilibrium to be 1:
Since the unbalanced transformer is formed, the withstand voltage can be increased even with a transmission line transformer in which a winding is wound around a binocular type core.

Further, in the amplification unit of the present invention, since the winding is wound around the binocular type core and the transmission line transformer is used,
Surface mounting is possible and automation is possible.

[Brief description of drawings]

FIG. 1 is a circuit diagram of an amplification unit using the transmission line transformer of the present invention and the related art.

FIG. 2 is a model view of a transmission line transformer of the present invention.

FIG. 3 is a winding diagram of one impedance conversion transformer used in the transmission line transformer of the present invention.

FIG. 4 is a winding diagram of the other impedance conversion transformer used in the transmission line transformer of the present invention.

FIG. 5 is an external view of a balanced-balanced transformer used in the transmission line transformer of the present invention.

FIG. 6 is a front view of a balanced-balanced transformer used in the transmission line transformer of the present invention.

FIG. 7 is a rear view of the balanced-balanced transformer used in the transmission line transformer of the present invention.

FIG. 8 is a load characteristic diagram of the transmission line transformer of the present invention.

FIG. 9 is a transmission characteristic diagram of the transmission line transformer of the present invention.

FIG. 10 is a model view of a conventional transmission line transformer.

FIG. 11 is a winding diagram of a conventional transmission line transformer.

[Explanation of symbols]

2 output transformer 3 First amplification circuit 4 Second amplifier circuit 40 impedance conversion transformer 41 Impedance conversion transformer 43 Balance-unbalance transformer 51 Binocular type core

Continued front page    F-term (reference) 5E070 AA16 BA20                 5J091 AA01 AA15 CA00 FA20 HA09                       HA25 HA29 HA37 MA04 MA11                       MA17 QA04 SA13 TA02 TA03                       UW10                 5J500 AA01 AA15 AC00 AF20 AH09                       AH25 AH29 AH37 AM04 AM11                       AM17 AQ04 AS13 AT02 AT03                       WU10

Claims (3)

[Claims] 1. A balanced-unbalanced transformer wound so that the impedance ratio becomes 1: 1 is connected to an impedance conversion transformer wound so that the impedance ratio becomes 9: 4, and the impedance ratio becomes 2: 1. A transmission line transformer characterized by forming a balanced-unbalanced transformer that becomes 1. 2. The transmission line transformer according to claim 1, wherein each of the windings is wound around a binocular type core. 3. An impedance conversion transformer wound to have an impedance ratio of 9: 4 is connected to each output terminal of a push-pull connected broadband amplifier circuit, and the impedance conversion transformer has an impedance ratio of 1: 1. A balanced-unbalanced transformer wound so as to have a ratio of 1: 1 is connected, and a transmission line transformer is configured so that the impedance ratio becomes 2: 1. An amplification unit characterized by connecting a balanced transmission line.