Telecommunications – Receiver or analog modulated signal frequency converter – Frequency modifying or conversion
Reexamination Certificate
2011-04-19
2011-04-19
Phu, Sanh D (Department: 2618)
Telecommunications
Receiver or analog modulated signal frequency converter
Frequency modifying or conversion
C455S313000, C455S323000, C455S341000, C455S318000, C327S113000
Reexamination Certificate
active
07929938
ABSTRACT:
Second-order intermodulation distortion can be suppressed in a direct conversion radio receiver having a downconversion mixer by calibrating resistors and a current source in the mixer. A test signal is applied to the signal inputs of the mixer transconductor. The resistances of first and second variable resistor circuits connected to the switching quad are then varied while also varying a variable current source. Each time the resistances and current are set to new values, the resulting mixer output signal is measured. When the measured output signal is determined to be at a minimum, the variable resistors and current source are left at the corresponding values to which they have been set. Adjusted in this manner, the current source counteracts the DC offset voltage at the mixer output.
REFERENCES:
patent: 6140849 (2000-10-01), Trask
patent: 6304142 (2001-10-01), Madni
patent: 6959178 (2005-10-01), Macedo et al.
patent: 2007/0077907 (2007-04-01), Rector
Macedo Jose
Sellars Shawn
Phu Sanh D
Skyworks Solutions Inc.
Smith Frohwein Tempel Greenlee Blaha LLC
Tempel Michael J.
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