Apparatus and method for applying frequency calibration to local oscillator signal derived from reference clock output of active oscillator that has no electromechanical resonator

A system comprising:

• a local oscillator (LO) signal generation circuit, arranged to generate an LO signal according to a reference clock, wherein the LO signal generation circuit comprises:
• an active oscillator, arranged to generate the reference clock, wherein the active oscillator comprises at least one active component, and does not include an electromechanical resonator;
• a receiver (RX) circuit, arranged to generate a down-converted RX signal by performing down-conversion upon an RX input signal according to the LO signal;
• and
• a calibration circuit, arranged to check a signal characteristic of the down-converted RX signal by detecting if a calibration tone exists within a receiver, set a frequency calibration control output in response to the calibration tone being not found in the receiver bandwidth, and output the frequency calibration control output to the LO signal generation circuit, wherein the LO signal generation circuit adjusts an LO frequency of the LO signal in response to the frequency calibration control output.

A calibration system comprising:

• a calibration signal source, arranged to generate a calibration reference signal;
• and
• a first system comprising:
• a first local oscillator (LO) signal generation circuit, arranged to generate a first LO signal according to a first reference clock, wherein the first LO signal generation circuit comprises:
• a first active oscillator, arranged to generate the first reference clock, wherein the first active oscillator comprises at least one active component, and does not include an electromechanical resonator;
• a first receiver (RX) circuit, arranged to generate a first down-converted RX signal by performing down-conversion upon a first RX input signal according to the first LO signal, wherein the first RX input signal is obtained from the calibration reference signal;
• and
• a first calibration circuit, arranged to check a signal characteristic of the first down-converted RX signal by detecting if a calibration tone exists within a receiver bandwidth, set a first frequency calibration control output in response to the calibration tone being not found in the receiver bandwidth, and output the first frequency calibration control output to the first LO signal generation circuit, wherein the first LO signal generation circuit adjusts an LO frequency of the first LO signal in response to the first frequency calibration control output.