Telecommunications – Receiver or analog modulated signal frequency converter – Frequency modifying or conversion
Reexamination Certificate
2011-05-17
2011-05-17
Vo, Nguyen (Department: 2618)
Telecommunications
Receiver or analog modulated signal frequency converter
Frequency modifying or conversion
C455S326000
Reexamination Certificate
active
07945230
ABSTRACT:
A passive, differential RF mixer reduces second order intermodulation interference while maintaining I/Q isolation via common mode feedback wherein the I and Q error signals in the feedback path are time multiplexing using a four-phase LO signal. An RF signal is received at a differential input having a center tap. The RF signal is mixed with an in-phase differential signal of the four-phase local oscillator signal in a differential mixer (I mixer). The RF signal is also mixed with a quadrature-phase differential signal Q components of the four-phase local oscillator signal in a differential mixer (Q mixer). The common mode levels of the I and Q differential mixer outputs are compared to a reference DC voltage to generate I and Q error signals. The I and Q error signals are time-multiplexed, and fed back to the RF input center tap.
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Coats & Bennett P.L.L.C.
Telefonaktiebolaget LM Ericsson (publ)
Vo Nguyen
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