Telecommunications – Receiver or analog modulated signal frequency converter – Local control of receiver operation
Reexamination Certificate
2007-08-21
2007-08-21
Vo, Nguyen T. (Department: 2618)
Telecommunications
Receiver or analog modulated signal frequency converter
Local control of receiver operation
C455S312000, C455S324000
Reexamination Certificate
active
10727612
ABSTRACT:
In a direct conversion receiver, to cancel a DC offset generated in the baseband processing block, negative feedback arrangements comprising a gain control amplifier and a low-pass filter are respectively attached to the I and Q signal branches of the baseband block following mixer outputs. The gain control amplifier in each negative feedback circuit is gain adjusted so that the product G-B of the gain G of a primary gain control amplifier and its own gain B will be constant and thereby the DC offset is cancelled. This DC offset cancellation can be applied in a continuous receiving system with no intermittent time during a receiving operation. Capacitance elements located off-chip can be reduced to those to be used only in the low-pass filters in the negative feedback circuits, whereas many off-chip capacitance elements have been required to be inserted between each stage of gain control amplifiers in conventional baseband chains.
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Harald Pretl, Werner Schelmbauer, Robet Weigel, Richard Hagelauer, Bernd Adler and Josef Fenk, “Circuit and system Considerations for UMTS Xero-IF Receivers in SiGe BiCMOS”, Microwave Workshop Digest (2001), pp. 264-268.
Akamine Yukinori
Hori Kazuaki
Tanaka Satoshi
Yamamoto Akio
A. Marquez, Esq. Juan Carlos
Fisher Esq. Stanley P.
Renesas Technology Corp.
Vo Nguyen T.
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