RF band clock spur harmonic canceller

A method for cancelling spurs without affecting an incoming signal, the method comprises the steps of:

• downconverting, by an integrated circuit radio frequency (RF) section on a substrate, an RF analog signal to an analog baseband signal;
• converting the analog baseband signal into a digital baseband signal, the digital baseband signal comprising incoming packets, wherein the digital baseband signal couples with a digital clock on the substrate to create a spur at an undesirable harmonic frequency near a frequency of the RF analog signal, and wherein the RF analog signal undesirably couples with the spur;
• iteratively estimates an amplitude and phase of the spur over a predetermined period of time, the spur being generated, at least in part, by the digital clock running on the substrate, wherein the estimating step comprises estimating the amplitude and phase of the spur in the absence of an incoming signal, and wherein the estimate of the amplitude and phase of the spur is mathematically based on a register value that adjusts a tracking rate of the spur;
• and
• subtracting the estimated spur from an incoming packet, wherein the estimated spur is a function of at least an exponential expression that includes at least one of a sampling frequency and a spur harmonic frequency.

In an integrated chip that downconverts a radio frequency (RF) analog signal into an analog baseband signal, an apparatus that cancels spurs that are generated, at least in part, by a digital clock running on a substrate of the integrated chip, the apparatus comprising:

• an analog-to-digital converter that converts an incoming analog baseband signal into a digital baseband signal, wherein the digital baseband signal couples with the digital clock to create a spur at an undesirable harmonic frequency near a frequency of the RF analog signal, and wherein the RF analog signal undesirably couples with the spur;
• an estimator that iteratively estimates an amplitude and phase of the spur when the analog-to-digital converter is not receiving the incoming analog baseband signal, wherein the estimator estimates the amplitude and phase of the spur in the absence of the digital baseband signal from the analog-to-digital converter, and wherein the estimate of the amplitude and phase of the spur is based on an iterative mathematical function that is mathematically based on a register value that adjusts a tracking rate of the spur;
• a multiplier that multiplies an output of the estimator with an output of a processor, the output of the processor comprising an exponential function that is a function of a sampling frequency and a spur harmonic frequency, the multiplier providing an estimated spur;
• and
• a subtractor that subtracts the estimated spur provided by the multiplier from the digital baseband signal provided by the analog-to-digital converter.