Mediatek Corporation

Analog Devices,inc.

Thomas J Liptay

Edmund J Balboni

Colm J Prendergast

Daniel E Fague

Phillip M Sher

Jeffrey R Feigin

Sriram Krishnan

A radio frequency (RF) receiver having an analog gain control section for controlling the gain of a received RF signal, and a digital demodulator section for demodulating the output of the gain control section, includes an analog GO circuit connected to recognize the presence of a data packet within a received RF signal in the analog gain control section, and in response to produce an analog GO signal, a digital GO circuit connected to recognize the presence of a data packet within the received RF signal from the digital demodulator section, and in response to produce a digital GO signal, and control circuitry connected to enable gain control functions within the analog gain control section and digital demodulator functions within the digital demodulator section in response to respective analog and digital GO signals.

Apparatus and method for RF packet detection and symbol timing recovery

An RF receiver includes an analog GO circuit that recognizes the presence of a data packet within a received RF signal in the receiver's analog gain control section, and in response produces an analog GO signal, and a digital GO circuit that recognizes the presence of a data packet from the receiver's digital demodulator section, and in response produces a digital GO signal. Gain control functions within the analog gain control section, and digital demodulator functions within the digital demodulator section, are enabled in response to respective analog and digital GO signals. The system is capable of distinguishing a valid data packet from noise, co-channel interference and adjacent panel interference. A symbol timing recovery circuit within the receiver identifies periodic samples of a data packet preamble that most closely match the preamble bits, with the receiver employing a continuation of the identified periodic samples to decode the remainder of the data packet.

Frequency offsets between a received carrier signal and a receiver's LO frequency are compensated by determining the offset and adjusting the phase of a demodulated signal derived from the modulated carrier. For frequency offsets that produce DC voltage offsets in I and Q components of the demodulated signal, the phase correction is implemented by operating upon the I and Q components with phase rotation operators in the form of sin &#x3b8; and cos &#x3b8;, where &#x3b8; is an angle whose tangent is the result of dividing the Q by the I frequency offsets.

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Cambridge, MA, United States of America

Thomas J Liptay