Pulse or digital communications – Receivers – Automatic baseline or threshold adjustment
Patent
1997-08-01
1999-12-28
Chin, Stephen
Pulse or digital communications
Receivers
Automatic baseline or threshold adjustment
375316, 375324, 375325, 375345, 375349, 329318, 329319, 329304, 329306, 329307, 455303, 455304, 455306, 455310, H04L 2506, H04L 2510, H04B 110
Patent
active
060091266
ABSTRACT:
Known is a zero intermediate frequency receiver or zero-IF receiver in which DC-offset correction is done in the I- and Q-paths, after mixing down of the received RF-signal or of an IF-signal. Such a DC-offset correction is not sufficient for high gain I- and Q-paths, particularly not in pagers for receiving long messages. Furthermore, no optimal power saving is achieved if such a receiver alternately operates in receive mode and sleep mode. A zero intermediate frequency receiver is proposed in which DC-offset correction is distributed over the high gain I- and Q-path. Preferably, blocking means are provided between DC-offset correction circuits and low pass filters in the I- and Q-path to prevent that an output signal of an upstream DC-offset correction circuit in the path excites a downstream low pass filter in the path during DC-offset correction. Herewith, considerable power savings are achieved.
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Chin Stephen
Maddox Michael W.
U.S. Philips Corporation
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