Miscellaneous active electrical nonlinear devices – circuits – and – Specific input to output function – Combining of plural signals
Reexamination Certificate
2000-05-30
2001-09-18
Le, Dinh T. (Department: 2816)
Miscellaneous active electrical nonlinear devices, circuits, and
Specific input to output function
Combining of plural signals
C327S355000, C327S113000, C455S333000
Reexamination Certificate
active
06292047
ABSTRACT:
FIELD OF THE INVENTION
This invention generally relates to mixers and particularly to a down conversion mixer circuit for use in a multi-stage receiver architecture, such as, for example, a quadrature receiver.
BACKGROUND OF THE INVENTION
A prevailing trend in today's wireless communications industry is the wholesale integration of radio frequency (RF) transceiver functionality onto a single die. A term frequently used by industry insiders when discussing the topic is the “single chip transceiver.” Despite the technical challenges associated with this endeavor, a small school of proponents believe Direct conversion techniques may provide a marketable set of solutions. As will be appreciated by those skilled in the art, Direct conversion refers to techniques whereby an incoming RF signal is received and converted directly to a set of baseband (audio) components without conversion to a set of Intermediate Frequency (IF) components.
In the receiver architecture anticipated above, the down-mixer circuit plays a critical role. It must be fast and support high frequency operation. It must exhibit strong Local Oscillation (LO) isolation characteristics, since the RF signal and the LO reference operate at the same frequency. It should have a low noise figure to improve receiver sensitivity. In addition, it must be energy efficient to help in the war on current drain. Based on the foregoing, it would be extremely advantageous to provide an improved down-mixer circuit and methodology optimized for use in a multi-stage direct conversion receiver.
REFERENCES:
patent: 5581210 (1996-12-01), Kimura
patent: 5945878 (1999-08-01), Westwick et al.
patent: 6121819 (2000-09-01), Traylor
Le Dinh T.
Motorola Inc.
Scutch, III Frank M.
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