Amplifiers – With distributed parameter-type coupling means
Reexamination Certificate
2002-05-13
2004-06-08
Shingleton, Michael B (Department: 2817)
Amplifiers
With distributed parameter-type coupling means
C330S054000, C330S12400D
Reexamination Certificate
active
06747511
ABSTRACT:
BACKGROUND
1. Field of Invention
The present invention relates to distributed amplifiers and, in particular, distributed amplifiers suited for wide-band and high-power applications.
BACKGROUND
2. Description of Prior Art
Distributed amplifiers are widely used in part to overcome the gain-bandwidth limitation due to inherent capacitance of the active devices associated with the resistive loads. Inductors and transmission lines are commonly employed to resonate with the device capacitance. The combinations of inductors and capacitors are approximately equivalent to delay elements (e.g., transmission lines) and thereby increase the operational bandwidth.
FIG. 1A
shows a conventional distributed amplifier
10
comprised of an analysis module
20
, a gain module
30
and a synthesis module
40
. The gain elements of the gain module
30
are identical and uniformly distributed in conjunction with the inductors. An equivalent-circuit model of an elementary section
50
of the distributed amplifier
10
is shown in FIG.
18
. The elementary section
50
is composed of two series inductors
51
and
52
, and a shunt capacitance
53
in the format of a T-configuration. The inductors
51
and
52
are the inductors in the analysis
20
or synthesis module
40
, while the capacitor
53
represents the device capacitance at the input or the output of the gain element. As the operation frequencies are lower than the resonance frequency of the components
51
,
52
, and
53
, the elementary section
50
is approximately equal to a piece of transmission line
60
as shown in FIG.
1
C. Virtually, a transmission line is a delay element with infinite bandwidth. Therefore, by combining device's capacitance
53
with the inductors
51
and
52
into a transmission line
60
, amplifiers with these types of analysis module and synthesis module can be operated over very wide frequency range. However, for the integrated circuit, the size of the inductor is comparably larger than the one for an active gain element. Moreover, the inductors in the analysis and synthesis modules are of two values, L and L/2, where L/2 is the inductance value on one arm of the T-configuration. This increases the complexity of the resulting design and implementation of the conventional analysis and synthesis modules. A simple architecture for the analysis and synthesis modules of the distributed amplifier is desirable and provided by the present invention.
SUMMARY OF THE INVENTION
The present invention is embodied as a circuit for a distributed amplifier where the analysis and synthesis lines are implemented in formats of a new &pgr;-configuration. In accordance with a preferred embodiment of the present invention, the connection of the inductors and the capacitive devices is in a format of a &pgr;-configuration, that is, two shunt device capacitances with a series inductor. The number of inductors is less by two than the number associated within a conventional distributed amplifier, in which the connection is in a format of a T-configuration. Moreover, according to the present invention, all the inductances of the synthesis, or analysis, lines are of the same value as opposed to the two different values in a conventional distributed amplifier. This sameness of value of the inductances is also present in the analysis lines of the present invention.
A distributed amplifier, according to the present invention, features compactness of integration and less complexity in designing the analysis and synthesis modules.
REFERENCES:
patent: 5227734 (1993-07-01), Schindler et al.
patent: 5550513 (1996-08-01), Wong
patent: 5559472 (1996-09-01), Kobayashi
patent: 5751190 (1998-05-01), Nguyen et al.
patent: 5920230 (1999-07-01), Beall
patent: 6094099 (2000-07-01), Kobayashi
patent: 460562 (1937-01-01), None
patent: 354136259 (1979-10-01), None
Moazzam et al. “A high gain dual-fed single stage distributed amplifier” IEEE MTT-S International Microwave Symposium Digest 1994 May 23-27, 1994 pp 1409-1412 vol. 3.
Liu Cheh-Ming Jeff
Sheng Neng-Haung
Brooks Michael B.
Euvis, Inc.
Michael Blaine Brooks P.C.
Shingleton Michael B
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