Compact power amplifier for microwave circuits

Details Compact power amplifier for microwave circuits Compact power amplifier for microwave circuits

1999-05-13

2001-01-30

Pascal, Robert (Department: 2817)

Amplifiers

With semiconductor amplifying device

Including field effect transistor

C330S286000, C330S295000, C330S307000

Reexamination Certificate

active

06181205

ABSTRACT:

The present invention relates to microwave circuits, and more particularly to those using monolithic microwave integrated circuit (MMIC) technology. More precisely, the invention relates to a compact amplifier circuit in MMIC technology.
BACKGROUND OF THE INVENTION
MMIC technology is commonly used for making microwave circuits for processing microwave signals, i.e. signals typically lying in the frequency range 1 GHz to 50 GHz or more.
FIG. 1
shows an example of a known power amplifier in MMIC technology. The amplifier of
FIG. 1
has four transistors
1
to
4
operating in parallel and fed by symmetrical voltage divider circuits; they output signals to voltage combiner circuits that are likewise symmetrical. In the example of
FIG. 1
, the amplifier has two input divider stages, and two output combiner stages. The input signal to the amplifier is applied to an input terminal
5
, and is then divided into two signals that are equal in amplitude and in phase in two branches
6
and
7
. The signals in each of these branches are in turn separated into two identical signals which are applied to the grid buses of the transistors
1
to
4
. More precisely, the signals in branch
6
are separated into two signals on branches
8
and
10
, which are applied to the grid buses of transistors
1
and
2
; the signals on branch
7
are separated into two signals on branches
9
and
11
, which are applied to the grid buses of transistors
3
and
4
. At the outputs from the transistors, the circuit is symmetrical about a line through the transistors. The signals delivered by the drain arrays of the transistors
1
and
2
to branches
14
and
16
are combined and applied to a branch
18
while the signals supplied by the drain arrays of the transistors
15
and
17
are combined and applied to a branch
19
. The signals from the branches
18
and
19
are combined and constitute the output signal on terminal
20
.
The circuit of
FIG. 1
presents the advantage of being very simple in design, with the signals being easy to divide and to combine. Nevertheless, it suffers from the drawback of being adaptable only to a number of transistors that is equal to an integer power of 2, four transistors in the example of FIG.
1
. This can lead to difficulties when dimensioning the various transistors forming the circuit. In addition, the circuit of
FIG. 1
occupies a large area on the circuit-supporting medium.
OBJECT AND SUMMARY OF THE INVENTION
The invention seeks to solve the problem of the bulkiness of amplifier circuits made using MMIC technology. It also has the object of solving the problem of assembling together an arbitrary number of transistors.
More precisely, the invention provides a power amplifier for microwave signals, the amplifier comprising a plurality of identical transistors, wherein: the grid buses of two adjacent transistors are interconnected by a grid matching circuit; the drain arrays of two adjacent transistors are interconnected by a drain matching circuit; the grid matching circuits are selected in such a manner as to ensure input levels to each transistor that are identical in amplitude and in phase; and the drain matching circuits are selected in such a manner as to present each transistor with optimum power impedance.
In an embodiment, the amplifier has an input terminal on the grid bus of a transistor; it may have an output terminal on the drain array of a transistor.
Advantageously, the amplifier is made out of MMIC technology.


REFERENCES:
patent: 4291286 (1981-09-01), Wagner
patent: 4543535 (1985-09-01), Ayasli
patent: 5012203 (1991-04-01), Beyer et al.
patent: 5172074 (1992-12-01), Shiga
patent: 0 012 093 A1 (1980-06-01), None
S. D. Agostino et al, “A 0.5-12 Ghz Hybrid Matrix Distributed Amplifier using Commercially Available FETS”.
MTT-S International Microwave Symposium Digest, Boston, Jun. 10-14, 1991, vol., 1, Jun. 10, 1991, pp. 289-292, XP000260409.

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