Analog open-loop VCO calibration method

A method for calibrating a voltage controlled oscillation, comprising:

• receiving a local oscillation signal and a reference signal;
• dividing the local oscillation signal by “N1” to create a first divided local oscillation signal and dividing the local oscillation signal by “N2” to create a second divided local oscillation signal, wherein “N1” and “N2” are not equal;
• dividing the reference signal by “N” to create a divided reference signal;
• converting the first and second divided local oscillation signals to an upper threshold voltage signal and a lower threshold voltage signal, respectively;
• converting the divided reference signal to a reference voltage signal;
• comparing the reference voltage signal to the upper and lower threshold voltage signals and producing a first and second logic signal therefrom;
• and
• producing a frequency compensation signal based on the first and second logic signals.

A direct conversion Radio Frequency (RF) transceiver integrated circuit comprising:

• a baseband processor for producing an outgoing baseband signal and for processing an incoming baseband signal;
• and
• wherein the baseband processor produces a frequency initiation signal for selecting and initiating a local oscillation frequency;
• a local oscillator that generates an RF local oscillation signal corresponding to an RF channel, the local oscillator further including a capacitor bank comprising a plurality of switched capacitors, and wherein analog open-loop VCO calibration circuitry selects at least one switched capacitor of the plurality of switched capacitors, the at least one switched capacitor for adjusting the tuning ranged of the VCO;
• a period-to-voltage conversion module coupled to receive a divided local oscillation and a divided reference signal, the period-to-voltage module to convert the divided local oscillation and the divided reference signal to a threshold voltage signal and a reference voltage signal, respectively;
• a comparator module coupled to receive the threshold and reference voltage signals, the comparator module for comparing the threshold and reference voltage signals and for producing a frequency adjustment signal;
• a receiver section operably coupled to the local oscillator to receive the RF local oscillation signal, wherein the receiver section receives an incoming RE signal, and wherein the receiver section down-converts, based partially upon a frequency compensation signal derived from the frequency adjustment signal by logic, the incoming RE signal based upon the RE local oscillation signal to produce the incoming baseband signal;
• and
• a transmitter section operably coupled to the local oscillator to receive the RE local oscillation signal, wherein the transmitter section receives an outgoing baseband signal, and wherein the transmitter section up-converts the outgoing baseband signal to produce an outgoing RE signal.

A method for open loop calibration of a voltage controlled oscillator (VCO), the method comprising:

• receiving, in a calibration circuit logic module, a calibration initiation signal containing at least one frequency divider number;
• dividing a local oscillation signal and a reference signal by the at least one frequency divider number to produce a divided local oscillation signal and a divided reference signal;
• converting, in a period-to-voltage converter, the divided local oscillation signal into a threshold voltage signal proportional to the period of the divided local oscillation signal;
• converting, in a period-to-voltage converter, the divided reference signal into a reference voltage signal proportional to the period of the divided reference signal;
• comparing the threshold voltage signal and the reference voltage signal to produce a frequency adjustment signal;
• generating a frequency compensation signal from the frequency adjustment signal, said frequency compensation signal comprising a binary signal having a plurality of values;
• and
• setting, with the frequency compensation signal, at least one switched capacitor from a plurality of switched capacitors in a capacitor bank, wherein setting the at least one switched capacitor changes the VCO tuning range.