Direct conversion receiver architecture

A method of operating an automatic gain control (AGC) loop in combination with a DC loop, comprising:

• selecting a particular DC operating mode for the DC loop from among a plurality of possible DC operating modes;
• operating the DC loop in the selected DC operating mode to correct for DC offset in a desired signal;
• selecting a particular AGC operating mode for the AGC loop from among a plurality of possible AGC operating modes based on the selected DC operating mode;
• and
• operating the AGC loop in the selected AGC operating mode to provide variable gain for the desired signal.

An control apparatus in a wireless communication system, comprising:

• means for selecting a particular DC operating mode for a DC loop from among a plurality of possible DC operating modes;
• means for operating the DC loop in the selected DC operating mode to correct for DC offset in a desired signal;
• means for selecting a particular AGC operating mode for an automatic gain control (AGC) loop from among a plurality of possible AGC operating modes based on the selected DC operating mode;
• and
• means for operating the AGC loop in the selected AGC operating mode to provide variable gain for the desired signal.

A method of operating a DC loop in a receiver unit, comprising:

• selecting a particular operating mode for the DC loop from among a plurality of possible operating modes that include an acquisition mode;
• and
• if the selected operating mode is the acquisition mode,
• operating the DC loop in the acquisition mode for a particular time duration to correct for DC offset in a desired signal, wherein the particular time duration is inversely proportional to a loop bandwidth for the DC loop for the acquisition mode, and
• transitioning out of the acquisition mode after the particular time duration.

An apparatus in a receiver unit, comprising:

• means for selecting a particular operating mode for a DC loop from among a plurality of possible operating modes that include an acquisition mode;
• and
• means for operating the DC loop in the acquisition mode for a particular time duration, if the selected operating mode is the acquisition mode, to correct for DC offset in a desired signal, wherein the particular time duration is inversely proportional to a loop bandwidth for the DC loop for the acquisition mode, and
• means for transitioning out of the acquisition mode after the particular time duration.

A method of digitally amplifying a desired signal, comprising:

• receiving a gain represented in a logarithm format;
• determining a difference between the received gain and a gain offset;
• converting the difference, represented in the logarithm format, to an output gain represented in a linear format;
• and
• digitally multiplying the desired signal with the output gain.

A digital variable gain amplifier (DVGA) comprising:

• a first unit operative to receive a gain represented in a logarithm format and to determine a difference between the received gain and a gain offset;
• a second unit operative to convert the difference, represented in the logarithm format, to an output gain represented in a linear format;
• and
• a digital multiplier operative to multiply input samples with the output gain to provide output data.

An apparatus for digitally amplifying a desired signal, comprising:

• means for receiving a gain represented in a logarithm format;
• means for determining a difference between the received gain and a gain offset;
• means for converting the difference, represented in the logarithm format, to an output gain represented in a linear format;
• and
• means for digitally multiplying the desired signal with the output gain.

A method of controlling one or more analog circuits via a serial bus, comprising:

• receiving a control for a particular analog circuit;
• forming a message corresponding to the received control;
• sending the message over the serial bus;
• receiving the message at the particular analog circuit;
• and
• adjusting one or more characteristics of the particular analog circuit based on the received message.

An apparatus for controlling one or more analog circuits via a serial bus, comprising:

• means for receiving a control for a particular analog circuit;
• means for forming a message corresponding to the received control;
• means for sending the message over the serial bus;
• means for receiving the message at the particular analog circuit;
• and
• means for adjusting one or more characteristics of the particular analog circuit based on the received message.

A receiver unit comprising:

• an RF front-end unit operative to amplify, downconvert, and digitize a received signal to provide samples;
• a digital signal processor operative to process the samples to provide output data;
• and
• a serial bus interface (SBI) unit operative to provide controls for the RF front-end unit via a serial bus.

A method of processing a desired signal in a wireless communication system, comprising:

• amplifying the desired signal with a first gain having a coarse resolution;
• downconverting the amplified signal from radio frequency (RF) to baseband with a single frequency downconversion stage;
• digitizing the downconverted signal to provide samples;
• and
• digitally amplifying the samples with a second gain having a fine resolution to provide output data having a desired signal amplitude.

A direct downconversion receiver comprising:

• an RF front-end unit operative to amplify, downconvert, and digitize a received signal to provide samples;
• a digital variable gain amplifier (DVGA) operative to amplify the samples with a first gain to provide output data having a desired signal amplitude;
• and
• an automatic gain control (AGC) loop operative to provide the first gain for the DVGA based in part on the output data.

An apparatus in a wireless communication system, comprising:

• first means for amplifying a received signal;
• means for canceling a DC offset in the amplified signal;
• second means for digitally amplifying the DC offset cancelled signal;
• and
• means for measuring the digitally amplified signal and to control the gains of the first and second amplifying means.

A receiver unit comprising:

• an analog variable gain amplifier;
• a DC offset canceller coupled to an output of the analog variable gain amplifier;
• a digital variable gain amplifier coupled to an output of the DC offset canceller;
• a gain controller adapted to measure a signal output from the digital variable gain amplifier and to control the gains of the analog and digital variable gain amplifiers;
• and
• a serial bus interface (SBI) unit operative to provide the gain for the analog variable gain amplifier via a serial bus.

A receiver unit comprising:

• an RF front-end unit operative to amplify, downconvert, and digitize a received signal to provide samples;
• a DC loop operative to cancel DC offset in the samples;
• a digital variable gain amplifier (DVGA) operative to amplify the DC offset canceled samples with a first gain to provide output data having a desired signal amplitude;
• an automatic gain control (AGC) loop operative to provide the first gain for the DVGA and a second gain for the RF front-end unit based in part on the output data;
• and
• a serial bus interface (SBI) unit operative to provide the second gain to the RF front-end unit.