Amplifiers – With semiconductor amplifying device – Including frequency-responsive means in the signal...
Reexamination Certificate
1999-09-27
2001-07-24
Pascal, Robert (Department: 2817)
Amplifiers
With semiconductor amplifying device
Including frequency-responsive means in the signal...
C330S257000, C330S307000
Reexamination Certificate
active
06265944
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to the field of voltage amplifier circuits and more particularly to an improved broadband radio frequency (RF) voltage amplifier circuit for communication devices, which includes a resonant circuit used to provide enhanced voltage gain, and a method for boosting the voltage amplifier gain and input signal frequency range in such a circuit.
2. Related Art
Many of today's conventional complementary metal-oxide-silicon (CMOS) field effect transistor (FET) amplifiers obtain the needed high gain by using two stages of voltage amplification, with each stage comprising a pair of load devices, a differential pair of devices and a current source, or by using a single stage voltage amplifier having a pair of load devices, two separate pairs of cascade devices, a differential pair of devices and a current source.
Conventional voltage amplifiers, usable in phase-locked loops (PLLs) of communication devices, typically utilize a gm-R voltage amplifier stage, for example, comprising a cascade of voltage amplifiers. Conventional gm-R voltage amplifiers may be made with bipolar technology, and may have resistive load or active load. Such conventional voltage amplifiers work only at frequency roll-off and thus are not flexible. Therefore, they are impractical in circuits needing to provide large frequency range, such as PLLs of communication devices. Thus, some conventional voltage amplifiers are additionally equipped with an external LC circuit, which is used as a bandpass filter and can only accept input amplifier signals within a narrow frequency bandwidth.
Therefore, conventional voltage amplifier circuits typically have limited use in high gain operations in RF voltage amplifier circuits because they cannot satisfy wide enough frequency bandwidth requirement of these circuits. Accordingly, there is a need in the art for an improved RF voltage amplifier circuit which operates at high gain with low power consumption, usable in communication devices. There is also a need for a method for increasing voltage gain and frequency bandwidth of an RF voltage amplifier circuit usable in communication devices.
SUMMARY OF THE DISCLOSURE
It is therefore an object of preferred embodiments of the present invention to provide a broadband RF voltage amplifier circuit which provides increased voltage gain and frequency bandwidth. The present invention includes several voltage amplifier circuit embodiments which can operate at high frequencies at wide frequency bandwidth, and corresponding method embodiments for increasing voltage gain and input signal frequency range in such circuits.
A preferred method embodiment includes the steps of providing a voltage amplifier and an integrated inductor for biasing the voltage amplifier. The next step involves selecting a resonant frequency of the integrated inductor at a frequency where the voltage amplifier gain is starting to roll-off, for boosting the voltage amplifier gain and the input signal frequency range. The integrated inductor preferably operates at a resonant frequency approximately matching the roll-off frequency of the voltage amplifier.
A first apparatus embodiment of the present invention includes a voltage amplifier having a transistor with the grounded source and the drain connected to a power supply via a resistive load, and an integrated inductor, for biasing the transistor, having an inductor connecting an input signal terminal to the gate of the transistor and a capacitor connecting the gate and the source of the transistor.
In another apparatus embodiment of the present invention, the voltage amplifier has a common emitter (CE) gain stage, a common base (CB) cascade stage directly-coupled to the CE gain stage, and a constant current mirror source. The integrated inductor has two inductors, each connected to one input of the amplifier input signal pair and a capacitor connecting the inductors. This circuit can be adapted for fully differential operation mode or for single ended operation mode.
REFERENCES:
patent: 4771247 (1988-09-01), Jacomb-Hood
patent: 4901032 (1990-02-01), Komiak
patent: 4973915 (1990-11-01), Batey
patent: 5231660 (1993-07-01), West, Jr.
patent: 5397978 (1995-03-01), Parry et al.
patent: 5907242 (1999-05-01), Gard
patent: 6026286 (2000-02-01), Long
Ali Akbar
Conta Matteo
Conexant Systems Inc.
Foley & Lardner
Nguyen Patricia T.
Pascal Robert
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