Continuously adjustable bandwidth discrete-time phase-locked loop
AssigneeInterDigital Technology Corporation
InventorsDavid K. Mesecher, Rui Yang, Ramon Cerda
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Abstract
A continuously adjusted bandwidth phase-locked loop is used by a B-CDMA™ receiver to correct for any deviation, or offset, that may exist between the received radio frequency (RF) carrier signal and the frequency of the first stage LO that converts the received RF carrier signal to an intermediate frequency (IF). The PLL in the receiver includes a filter with an adjustable bandwidth. A wider bandwidth is used during initial acquisition of the received signal. After the PLL has acquired the received carrier signal using the wider bandwidth, the bandwidth of the filter is gradually narrowed to provide a low steady-state error.
Claims11
A terrestrial CDMA RF receiver for receiving a CDMA communication signal transmitted on a selected RF carrier frequency and removing said RF carrier frequency to provide a received information signal;
- the receiver including a system for correcting phase errors in said information signal which has been transmitted on said selected RF carrier frequency channel;
- the correction system comprising:
- a local oscillator for generating a mixing signal;
- a mixer for combining said mixing signal with said information signal to produce a correction signal;
- analyzer for analyzing the phase of said correction signal and generating an error signal based on the deviation of the analyzed phase from a predetermined phase;
- and
- a bandwidth controller for recursively adjusting the phase of said correction signal such that the phase of said correction signal is equal to said predetermined phase;
- said bandwidth controller for selecting a bandwidth with an adjustable range based on said correction signal, estimating an offset by interrogating said error signal;
- and modifying said correction signal by said offset.
Dependencies are inferred from the claim text.