Amplifiers – With semiconductor amplifying device – Including frequency-responsive means in the signal...
Reexamination Certificate
1998-11-20
2001-03-06
Pascal, Robert (Department: 2817)
Amplifiers
With semiconductor amplifying device
Including frequency-responsive means in the signal...
C330S307000
Reexamination Certificate
active
06198352
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to radio frequency communication and more particularly to low noise amplifiers used in radio frequency signal transmission systems.
2. Description of Related Art
Low noise amplifiers (LNAs) are used in conjunction with numerous radio frequency functions, for example, mixers, voltage controlled oscillators, limiters, filters, etc. As such, the cost of a LNA is significant to the overall cost of the function. Generally, the cost of a LNA is determined by two factors: (1) the integrated circuit (IC) cost; and (2) the cost of off-chip components that are necessary to the operation of the LNA and to the matching of the LNA with other radio frequency functions. Currently, to achieve a low noise amplifier that is easily integrated with other radio frequency functions, it has been necessary to use a multitude of off-chip components which inherently increases the expense. Alternatively, application specific integrated circuits (ASICs) can be fabricated to include all the necessary components onto one chip, however, this process is an expensive, detailed fabrication process.
Further, while state-of-the-art LNAs are capable of providing a noise figure approaching 1.5 dB they generally use 45 to 90 mW of power, e.g. see Mini-Circuits Corporation model VAM-6, an undesirably high figure.
In an attempt to address some of the concerns described above, U.S. Pat. No. 5,574,405 describes a low noise amplifier (LNA)/mixer/frequency synthesizer circuit for an RF system. The LNA/mixer/frequency synthesizer circuit of the '405 patent is fabricated as an integrated circuit using CMOS technologies. In the '405 patent, the LNA portion of the circuit comprises a first transistor directly coupled to an antenna port, a current mirror to set a predetermined bias current to the first transistor and an inductor, which couples the first transistor to the frequency synthesizer circuit. The '405 patent does not address integrating the LNA with radio functions other than the mixer and frequency synthesizer circuits and, as such, does not provide for both input and output impedance matching. Further, the LNA provides only a single stage of amplification, limiting the overall range of programmable amplification.
As such, there is a need for a LNA that can reduce the number of off-chip components and utilize an IC fabricated with low-cost, CMOS technology to significantly reduce the cost of the LNA and the overall cost of the radio frequency functions with which the LNA is integrated while at the same time provide a noise figure comparable to current, state-of-the-art LNAs, reduced power consumption and a broad range of programmable amplification.
SUMMARY OF THE INVENTION
The needs described above are in large measure met by a radio frequency, low noise amplifier (LNA) of the present invention. The LNA of the present invention comprises an input stage including an input inductor and an input circuit portion. The input circuit portion is operably connected to the input inductor and includes an input gain portion. The LNA further comprises an output stage that is operably connected to the input stage. The output stage includes an output inductor and an output circuit portion. The output circuit portion is operably connected to the output inductor and includes an output gain portion. The input and output inductors are distinct, off-chip components. However, the input circuit portion and output circuit portion are fabricated on a single, integrated circuit chip with CMOS technology. The input stage includes an input impedance that is matched to a system impedance while the output stage includes an output impedance that is matched to the system impedance.
The present invention further comprises a method of producing an amplified radio signal. The method includes the steps of: (1) receiving a radio frequency input signal; (2) resonating an input inductance with an input reactance so as to cancel the input reactance and present an input impedance to the input signal; (3) amplifying the input signal; (4) resonating an output inductance with an output reactance so as to cancel the output reactance and present an output impedance to the amplified input signal; and (5) producing an amplified output signal by further amplifying the amplified input signal.
REFERENCES:
patent: 4658220 (1987-04-01), Heston et al.
patent: 4853649 (1989-08-01), Seino et al.
patent: 5111157 (1992-05-01), Komiak
patent: 5574405 (1996-11-01), Razavi
patent: 5663690 (1997-09-01), McGinn
patent: 5757230 (1998-05-01), Mangelsdorf
patent: 5764109 (1998-06-01), Kukkonen
patent: 5818880 (1998-10-01), Kriz et al.
Applied Micro Circuits Corporation
Gray Cary Ware & Freidenrich
Nguyen Patricia T.
Pascal Robert
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