JP2003008363A - Wide band amplification circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable hybrid constitution by mounting MESFETs or the like for constituting a wide band amplification circuit on a single layer board. SOLUTION: This wide band amplification circuit is provided with a first amplification circuit 25 and a second amplification circuit 26 which are push-pull connected between an input transformer 20 and an output transformer 22 and constituted of a plurality of stages of MESFETs 27a, 27b, 28a, 28b, 29a, 29b. A plurality of stages of the MESFETs, wide band blocking inductors 32a, 32b and other chip components are attached on the single layer board. Gate bias wires 30 of the MESFETs are made to pass under the inductors 32a, 32b.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wide band amplifier circuit for stably amplifying a signal over a multi-channel wide band such as CATV.

[0002]

2. Description of the Related Art In CATV and the like, it has been attempted to realize more than 100 video signal channels. Normally, one channel has a frequency band of about 6 MHz, so in order to increase the number of channels to 100 channels, a wide-band amplifier circuit capable of amplifying with low distortion and uniform high gain over a wide frequency band of about 600 MHz is required. To be done.

FIG. 3 shows a conventional wide band amplifier circuit. A first amplifier circuit 3 and a second amplifier circuit 4 are provided between a power distributor 1 such as an input transformer connected to the input terminal IN and a power combiner 2 including an output transformer connected to the output terminal OUT. And are connected to push-pull.

The first amplification circuit 3 includes a MESFET 5a for the first-stage amplification and a MESF for the second-stage amplification in which the gate electrode is connected to the drain electrode of the MESFET 5a.
ET6a and MESFET6a for the second stage amplification. M for the third stage amplification in which the source electrode is connected to the drain electrode.
It is composed of ESFET 7a. ME for the first-stage amplification
A resistor 8 is provided between the drain electrode and the gate electrode of the SFET 5a.
The first feedback circuit 10a including the capacitor a and the capacitor 9a is connected. Further, the drain electrode of the third-stage amplification MESFET 7a and the gate electrode of the second-stage amplification MESFET 6a have a second resistor 11a and a capacitor 12a.
The feedback circuit 13a is connected.

The second amplifier circuit 4 is also the first amplifier circuit 3
MESFET5 for the first stage amplification with the same configuration as
b, a MESFET 6b for second-stage amplification in which the gate electrode is connected to the drain electrode of the MESFET 5b, and a MESFET 7b for third-stage amplification in which the source electrode is connected to the drain electrode of the MESFET 6b for second-stage amplification
And consists of.

A third feedback circuit 10b consisting of a resistor 8b and a capacitor 9b is connected between the drain electrode and the gate electrode of the first stage amplification MESFET 5b. In addition, the drain electrode of the MESFET 7b for the third amplification and the second
A resistor 1 is connected to the gate electrode of the MESFET 6b for the stage amplification
Fourth feedback circuit 13b including 1b and capacitor 12b
Are connected.

The source electrodes of the first-stage amplification MESFET 5a and MESFET 5b are coupled by a resistor 15, and similarly, the second-stage amplification MESFET 6a and M are also connected.
The source electrode of the OSFET 6b is coupled with the resistor 16. Furthermore, the third-stage amplification MESFET 7a and the gate electrode of the MESFET 7b are connected by a resistor 17.

The first stage MESFET 5a and MESFET 5b for amplification and the second stage MESFE for amplification.
The source electrodes of T6a and MESFET6b have a resistance of 1
5 and resistor 16 are virtually grounded, and these MESFE
T5a, MESFET5b and MESFET6a, MES
The secondary distortion due to the variation in the characteristics with the FET 6b is removed, and the stability is improved. A bias voltage is supplied to the gate electrodes of the third-stage amplification MESFET 7a and MESFET 7b by a resistor 17 to suppress the gain on the high frequency side and stabilize the gain grounding operation.

Therefore, the input signal applied to the input terminal IN is supplied to the MESFET 5a for amplifying the first stage and MESFE.
T5b and the second stage MESFET 6a for amplification and M
Amplified by ESFET6b, M for the third stage amplification
It is amplified by the ESFET 7a and the MESFET 7b. The third stage amplification MESFET 7a and MESFET 7b
The high frequency output signal amplified by is output to the output terminal OUT via the power combiner 2.

[0010]

As described above, the conventional wide-band amplifier circuit uses the MESFET 5a for the first-stage amplification.
And a first amplification circuit 3 including a second-stage amplification MESFET 6a and a third-stage amplification MESFET 7a.
Similarly, MESFET 5b for the first stage amplification, and the second
MESFET 6b for the third stage amplification and M for the third stage amplification
The ESFET 7b and the second amplifier circuit 4 including the ESFET 7b are connected to each other by push-pull.

As described above, in addition to the six MESFETs, the circuit components such as the ground resistance and the bias resistance are composed of one chip, so that a high level of technology is required. In addition, the wiring of the wiring on the substrate to which the chip is attached becomes a little complicated. Furthermore, a dedicated package for mounting a one-chip IC is required.

[0012]

The first aspect of the present invention includes an input transformer to which a high frequency signal is applied, an output transformer for extracting the high frequency signal, and a plurality of stages of MESFETs which are push-pull connected between the input transformer and the output transformer.
And a second amplifying circuit, the multistage MESFET and the wideband blocking inductor are mounted on a single-layer substrate, and a wideband amplifying circuit is provided in which the gate bias line of the MESFET is passed under the wideband blocking inductor. .

According to the present invention, an input transformer to which a high frequency signal is applied, an output transformer for extracting the high frequency signal,
It comprises a first amplifier circuit and a second amplifier circuit having a plurality of stages of MESFETs which are push-pull connected between the input transformer and the output transformer, and the first amplifier circuit and the second amplifier circuit have a high frequency at their gate electrodes. An input signal is applied, the source electrodes are coupled with a resistor, and the pair of upper and lower first electrodes are virtually grounded.
The top and bottom of which the gate electrode and the gate electrode are connected to a bias source by a common gate bias line, and the source electrode is connected to the drain electrode of the first stage MESFET through the resistor and the broadband blocking inductor to the first stage MESFET, respectively. A pair of second-stage MESFETs, a plurality of stages of MESFETs, circuit components, and high-frequency blocking inductance are attached to a single-layer substrate, and the gate bias lines of the second-stage MESFETs are connected to the first-stage MESFETs and the second-stage MESFETs. Eye MESF
A wideband amplifier circuit is provided that passes under a wideband blocking inductor connecting ET.

Furthermore, the present invention provides the first amplifier circuit and the second amplifier circuit.
A wide-band amplifier circuit in which the gain band of the amplifier circuit is uniform and the stop band of the wide-band blocking inductance is substantially the same.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION A wide band amplifier circuit according to the present invention will be described with reference to FIGS.

In FIG. 1, the input transformer 20 is a winding 2
0a, 20b, 20c, 20d. One end of the winding 20a is connected to the input terminal 21 to which a high frequency input signal such as CATV is applied, the other end is connected to one end of the winding 20d, and the windings 20b and 20c are connected to each other. .

The output transformer 22 includes windings 22a, 22b,
22c and 22d. The output end of the winding wire 22a is connected to the output terminal 23 and the output end of the winding wire 22d, and the output ends of the winding wire 20b and the winding wire 20c are connected to each other.

The input transformer 20 and the output transformer 22
A first amplifier circuit 25 and a second amplifier circuit 26 are connected in between. The first amplifier circuit 25 is the first stage MESFET2
7a, second stage MESFET 28a and third stage MESF
It consists of ET29a.

The gate electrode of the first stage MESFET 27a is connected to one end where the winding 20b and the winding 20c of the input transformer 20 are connected. The first stage MES
The drain electrode of the FET 27a and the second stage MESFET2
The gate electrode of 8a is connected to the capacitor 30a through the resistor 30b.

The gate electrode of the second stage MESFET 28a is connected to a bias source 31 via a gate bias line 30 having resistors 30c and 30d. Further, the drain electrode of the first-stage MESFET 27a and the source electrode of the second-stage MESFET 28a are DC-connected via the broadband blocking inductor 32a and the resistor 33a.

The third stage MESFE with the gate grounded
The source electrode of T29a and the drain electrode of the second stage MESFET 28a are connected, and the third stage MES is connected.
The drain electrode of the FET is connected to the winding 22c of the output transformer 22 via the inductor 35a.

A resistor 37a and a capacitor 38 are provided between the drain electrode and the gate electrode of the first stage MESFET 27a.
The first feedback circuit 39a serving as a is connected to the source electrode of the third stage MESFET 29a and the second stage MESFE.
A second feedback circuit 43a including resistors 40a and 41a and a capacitor 42a is connected between the gate electrodes of T28a.

The second amplifier circuit 26 also has a circuit configuration similar to that of the first amplifier circuit 25, and comprises a first stage MESFET 27b, a second stage MESFET 28b and a third stage MESFET 29b whose gate is grounded.

The gate electrode of the first stage MESFET 27b is connected to one end where the windings 20a and 20d of the input transformer 20 are coupled. The first stage MESFE
The drain electrode of T27b and the second stage MESFET 28b
The gate electrode of is connected to the capacitor 30e and the resistor 30f.

The gate electrode of the second stage MESFET 28b is connected to the bias source 31 through the gate bias line 30 having the resistors 30c and 30d, and the first
The drain electrode of the second-stage MESFET 27b and the second-stage ME
The source electrode of the SFET 28b is the broadband blocking inductor 3
It is connected in a direct current manner via 2b and a resistor 33b.

Third stage MESFE with the gate grounded
The source electrode of T29b and the drain electrode of the second stage MESFET 28b are connected to each other, and the third stage MES is connected.
The drain electrode of the FET 29b is connected to the winding 22d of the output transformer 22 via the inductance 35b.

A resistor 37b and a capacitor 38 are provided between the drain electrode and the gate electrode of the first stage MESFET 27b.
b is connected to the first feedback circuit 39b, and the drain electrode of the third stage MESFET 29b and the second stage MESF are connected.
A second feedback circuit 43b including resistors 40b and 41b and a capacitor 42b is connected between the gate electrodes of the ET 28b.

The first amplifier circuit 25 and the second amplifier circuit 26.
And are push-pull connected. That is, the first stage M
The ESFET 27a and the MESFET 27b and the source electrodes of the second stage MESFET 28a and the MESFET 28b are virtually grounded by a resistor 45 and a resistor 46, respectively.
These MESFET 27a, MESFET 27b and ME
The secondary distortion due to the variation in the characteristics of the SFET 28a and the MESFET 28b is removed, and the stability is improved.
Also, the third stage MESFET 29a and MESFET 2
A bias voltage is supplied to the gate electrode of 9b by resistors 47 and 48 to suppress the gain on the high frequency side and stabilize the gain grounding operation.

In the wide band amplifier circuit of the present invention, the six bare MESFETs 27a, 27b, 28a, 28b are formed.
And 29a, 29b, broadband blocking inductors 32a, 32
b and other 40 chip parts such as resistors and capacitors, a single aluminum plate or alumina (AL
_It is mounted on a substrate of ₂ O ₃ ) or alumina nitride (ALN) to reduce the cost.

Moreover, the first amplifying circuit 25 and the second amplifying circuit 26 are push-pull connected and arranged symmetrically. In particular, the broadband blocking inductors 32a and 32b take up space and pose a wiring problem.

As shown in FIG. 2, the first amplifier circuit 2
5 and the gain of the second amplifier circuit 26 are 10 MHz to 1 GHz
It is almost uniform over the entire range. On the other hand, the blocking frequency band of the broadband blocking inductances 32a and 32b is set to the first amplification circuit 2
5 and the frequency band of the gain of the second amplifying circuit 26, which is substantially the same as 10
Therefore, according to the present invention, the gate bias line 30 which connects the gate electrodes of the second stage MESFET 28a and MESFET 28b and is connected to the bias source 31 is connected to the wide band blocking inductances 32a and 32.
The wiring is made to pass under b.

Thus, the broadband blocking inductance 3
Since no signal flows in the frequency band of 10 MHz to 1 GHz in 2a and 32b, and also no signal flows in the gate bias line, the broadband blocking inductances 32a and 32b.
Even if the gate bias line 30 is provided under 2b, there is almost no mutual interference.

The wide band amplifier circuit of the present invention has the above-mentioned configuration. A high frequency signal such as CATV applied to the input terminal 21 is transmitted through the input transformer 20 to the first stage ME.
There is no distortion in the SFETs 27a and 27b, and the second stage M
ESFETs 28a, 28b and the third stage MESFET2
It is amplified by 9a and 29b. The amplified high frequency output signal is taken out from the output transformer 22 to the output terminal 23.

[0034]

The wideband amplifier circuit of the present invention is push-pull connected between the input transformer and the output transformer and has a plurality of ME stages.
A first amplifying circuit and a second amplifying circuit made of SFET are provided, and the plurality of stages of MESFETs and the broadband blocking inductor are mounted on a single layer substrate so that the gate bias line of the MESFET passes under the broadband blocking inductor. Because it is set, it can be configured with hybrid.

Moreover, since the frequency band in which the gains of the first amplifier circuit and the second amplifier circuit are uniform and the blocking frequency band of the broadband blocking inductance are substantially the same, the gate bias line passes under the broadband blocking inductor. Even if the wiring is performed as described above, a stable amplifying operation in which the high-frequency signal is influenced by the signal line can be realized.

[Brief description of drawings]

FIG. 1 is a circuit diagram of a wideband amplifier circuit of the present invention.

FIG. 2 is a characteristic diagram showing a gain frequency characteristic of a wideband amplifier circuit of the present invention and a blocking frequency characteristic of a wideband blocking inductor.

FIG. 3 is a circuit diagram of a conventional wide band amplifier circuit.

[Explanation of symbols]

20 input transformer 21 Input terminal 22 output transformer 23 output terminals 25 First amplifier circuit 26 Second amplifier circuit 27a, 27b 1st stage MESFET 28a, 28b Second stage MESFET 29a, 29b Third stage MESFET 30 gate bias line 32a, 32b Broadband blocking inductance

Claims (4)

[Claims] 1. An input transformer to which a high-frequency signal is applied, an output transformer for extracting the high-frequency signal, a first amplifier circuit having a plurality of stages of MESFETs connected by push-pull between the input transformer and the output transformer, and a second amplifier circuit. A broadband amplifier circuit comprising an amplifier circuit, wherein a plurality of stages of MESFETs, a broadband blocking inductor and chip parts are mounted on a single layer substrate, and a gate bias line of the MESFET is passed under the broadband blocking inductor. 2. An input transformer to which a high frequency signal is applied, an output transformer for taking out the high frequency signal, a first amplifier circuit having a plurality of stages of MESFETs connected by push-pull between the input transformer and the output transformer, and a second transformer. The first and second amplifying circuits are composed of a pair of upper and lower first stage MESFETs in which a high-frequency input signal is applied to the gate electrode and the source electrode is coupled by a resistor and is virtually grounded. , The gate electrode is connected to the bias source by the common gate bias line, and the first stage MESF is connected via the broadband blocking inductor.
A pair of upper and lower second stage MESFETs connected to ET respectively
And a plurality of stages of MESFETs, a broadband blocking inductor and a chip component are attached to a single layer substrate, and the second stage ME is provided.
A wide band amplifier circuit, wherein a gate bias line of an SFET is passed under a wide band blocking inductor connecting a first stage MESFET and a second stage MESFET. 3. The broadband amplifier circuit according to claim 1, wherein the single-layer substrate is a single aluminum plate, alumina, or aluminum nitride. 4. The frequency band in which the gains of the first amplifier circuit and the second amplifier circuit are uniform and the stop frequency band of the wideband stop inductor is substantially the same. The broadband amplifier circuit described.