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US 2006/0133532 A1Published application
Hardware efficient FSK demodulator
AssigneeBroadcom Corporation
InventorsHenrik Jensen, Paul Lettieri
Life of this patent
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Abstract
A radio frequency (RF) transmitter includes a digital radio processor and a baseband processor. A complex analog-to-digital converter (ADC) within the radio processor provides an analog interface to the baseband processor to receive an analog complex modulated baseband signal and convert the analog complex modulated baseband signal to a digital complex modulated baseband signal. A demodulator within the radio processor demodulates the digital complex modulated baseband signal to recreate the original transmit digital data as a demodulated digital signal. The demodulated digital signal is processed by a digital processor in the radio processor to mitigate the effects of various imperfections in the radio processor circuitry.
Claims20
A radio frequency (RF) transmitter, comprising:
- a baseband processor for digitally processing outgoing data, wherein the baseband processor is operable to produce an analog complex modulated baseband signal;
- and
- a radio processor, including:
- a complex analog-to-digital converter (ADC) connected to receive the analog complex modulated baseband signal, wherein the analog-to-digital converter is operable to convert the analog complex modulated baseband signal to a digital complex modulated baseband signal;
- a digital low pass filter coupled to receive the digital complex modulated baseband signal, the digital low pass filter for producing a low pass filtered outgoing digital signal;
- a demodulator connected to receive the digital complex modulated baseband signal, wherein the demodulator is operable to demodulate the digital complex modulated baseband signal to produce a demodulated digital signal, the demodulator further comprising:
- a CORDIC for producing a phase component based upon the digital complex modulated baseband signal, the phase component having a precise digital phase value;
- and
- a quantizer for producing a high pass filtered coarse digital phase value based upon the phase component having the precise digital phase value;
- timing recovery circuit for generating the demodulated digital signal;
- a digital processor connected to receive the demodulated digital signal, wherein the digital processor is operable to process the demodulated digital signal to produce a processed modulated digital signal;
- a digital-to-analog converter (DAC) connected to receive the processed modulated digital signal, wherein the DAC is operable to convert the processed modulated digital signal to a continuous waveform signal;
- an analog filter connected to receive the continuous waveform signal, wherein the filter is operable to produce a filtered signal, and
- a translational loop connected to receive the filtered signal, wherein the translational loop is operable to convert the filtered signal to a Radio Frequency (RF) transmit signal.
11 more elements
A radio transmitter, comprising:
- baseband processor for generating outgoing analog baseband frequency signals;
- analog-to-digital conversion circuitry for producing outgoing digital baseband signals based upon the outgoing analog baseband frequency signals;
- low pass digital filtering circuitry for producing low pass filtered outgoing digital signals based on the outgoing digital baseband signals;
- vector de-rotator for extracting and producing a precise phase component of the low pass filtered outgoing digital signals;
- delta sigma quantizer for producing a coarse phase component based upon the precise phase component;
- coarse phase component processing circuitry for producing digital data based on the coarse phase component;
- timing recovery circuit for synchronizing sampling of the digital data;
- digital processor for digitally processing the digital data and producing outgoing data signals;
- and
- analog front end for converting the outgoing data signals to analog signals and for upconverting the analog signals to RF for transmission.
7 more elements
A method for digitally modulating a signal for transmission over an air interface, comprising the steps of:
- modulating digital output data to produce a first digital complex modulated baseband signal;
- converting the first digital complex modulated baseband signal to an analog complex modulated baseband signal;
- converting the analog complex modulated baseband signal to a second digital complex modulated baseband signal;
- demodulating the second digital complex modulated baseband signal to produce a demodulated digital signal which demodulated digital signal is based upon a coarse phase component;
- processing the demodulated digital signal to produce a processed modulated digital signal;
- and
- converting the processed modulated digital signal to a Radio Frequency (RF) transmit signal.
4 more elements
A method for demodulating a signal, comprising:
- coordinate rotating a complex baseband phase signal to produce a phase component, the phase component characterized by a precise digital phase value;
- producing a coarse digital phase value based upon the precise digital phase value;
- differentiating the coarse digital phase value and producing a differentiated output comprising one of a positive or a negative indication of a rate of change of the coarse digital phase value;
- low pass filtering the differentiated output to produce a smooth low pass filtered differentiated output;
- accumulating and dumping the smooth low pass filtered differentiated output and generating an output signal having a signed value representing one of a logic one and a logic zero;
- and
- recovering timing the output signal to produce a demodulated digital signal.
4 more elements
Dependencies are inferred from the claim text.