Signal oscillation circuit with adaptive tuning for tail filters

A signal oscillation circuit comprising:

• a voltage-controlled oscillator (VCO) that includes a VCO core and a tail filter coupled to the VCO core, the tail filter including a tunable component;
• a logic circuit including a first output coupled to a control input of the tunable component of the tail filter;
• and
• a signal converter including an input coupled to a second output of the logic circuit and including an output coupled to a node of the VCO, wherein the logic circuit comprises:
• a digital signal generator including an output coupled to the input of the signal converter;
• a delay element having an input coupled to the output of the digital signal generator;
• a correlator including a first input coupled to an input of the logic circuit and including a second input coupled to an output of the delay element;
• a first digital gain component including an input coupled to an output of the correlator and having a first gain;
• a second digital gain component including an input coupled to the output of the correlator and having a second gain different than the first gain;
• a multiplexer including a first input coupled to an output of the first digital gain component and including a second input coupled to an output of the second digital gain component;
• and
• an accumulator including an input coupled to an output of the multiplexer and including an output coupled to the first output of the logic circuit.

A method of oscillating signal generation, the method comprising:

• controlling an oscillating signal output by a voltage-controlled oscillator (VCO) using a tuning signal;
• generating a training signal;
• applying the training signal to a node of the VCO for upconversion by the VCO, wherein the training signal is different than the tuning signal;
• determining a phase difference between a reference signal and a processed version of the oscillating signal;
• and
• based on the phase difference, tuning at least one tail filter of the VCO, wherein the tuning at least reduces an upconversion gain of the VCO and wherein the tuning comprises:
• converting the phase difference to a digital representation of the phase difference;
• delaying the training signal to generate a delayed training signal;
• correlating the delayed training signal with the digital representation of the phase difference to generate a correlation;
• and
• tuning the at least one tail filter of the VCO based on the correlation.