Motorola Corporation

Frederick J Martin

Robert E Stengel

David E Bockelman

Jui-Kuo Juan

A delay locked loop frequency synthesizer in several embodiments uses a primary delay line element () and one or more secondary delay elements (). In one embodiment, a main delay line () is used to coarsely select a frequency output while a secondary delay element (), either passive or active, is used to increase the resolution of the primary delay line (). In the passive embodiment, a coarse and fine frequency selection is possible by selecting components from the output taps of the main delay line () as a driving signal for the passive secondary delay element () to provide the coarse adjustment and selecting an output from the secondary delay element () to provide the fine selection.

Cascaded delay locked loop circuit

A digital IF to base band demodulator ( ) includes delta sigma samplers ( ) for sampling two channels of an IF signal at a sampling rate that is substantially higher than the Nyquist rate for the IF signal. A first pair of decimation filters ( ) decimates and filters the output of the delta sigma samplers ( ) but keeps the samples at a rate sufficient to perform digital mixing, cross adding, and pulse shape match filtering. A set of mixers ( ) mixers the output of the first pair of decimation filters with two phases of a digital representation of an local IF signal. A pair of summers ( ) sums, and subtracts outputs of the set of mixers ( ) in order to cancel undesired harmonics. A second set of decimation filters ( ) decimates and filters the output of the summers ( ) applying a filter function that is matched to a pulse shape of a base band signal present in the IF signal.

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Plantation, FL, United States of America

Frederick J Martin