Local oscillator system and frequency switching method for minimizing spurious components

A local oscillator system for an RF communication system, comprising:

• an oscillator generating a first signal with a fixed frequency of k times as much as a given frequency, where k is an integer of two or more;
• frequency dividers respectively connected to said oscillator, each of said frequency dividers receiving said first signal from said oscillator and dividing the frequency of said first signal by a dividing factor of k;
• control means for controlling said frequency dividers so that one of said frequency dividers is operating while the remaining frequency dividers are not operating;
• frequency generators for generating second signals, said second signals being different in frequency from each other;
• frequency mixers, each of which mixes the frequency of an output signal output from a corresponding one of said frequency dividers with said second signal from a corresponding one of said frequency generators;
• filters respectively connected to said frequency mixers, each of which selects a component with a desired local frequency from an output signal of a corresponding one of said frequency mixers;
• and
• an output terminal connected to said filters;
• wherein said component with said desired local frequency is derived through one of said filters corresponding to an operating one of said frequency dividers.

A frequency switching method of a local oscillator system for an RF communication system, said method comprising the steps of:

• generating signals having different frequencies;
• dividing a frequency of one of said signals by a dividing factor n by controlling frequency dividers so that one of said frequency dividers is in an active operation mode and the remaining frequency dividers are in an inactive operation mode, wherein n is an integer equal to or greater than two;
• combining a signal output from one of said frequency dividers which is in an active operation mode and at least one signal output from the remaining frequency dividers which are in an inactive operation mode, thereby generating a single output signal;
• and
• selecting a component with a frequency obtained through said dividing step from said single output signal as a local signal.

A frequency switching method of a local oscillator system comprising the steps of:

• generating a first signal with a fixed frequency of k times as much as a given frequency, where k is an integer of two or more;
• dividing the frequency of said first signal by a dividing factor k by using frequency dividers to output resulting frequency-divided signals, respectively, said frequency dividers being controlled so that one of said frequency dividers is in operation and the remaining frequency dividers are out of operation;
• generating second signals with different frequencies;
• mixing the frequency of one of said frequency-divided signals outputted from an operating one of said frequency dividers with the frequency of a corresponding one of said second signals;
• and
• selecting a component with a desired local frequency from an output signal generated in the mixing step;
• wherein said component with said desired local frequency is derived through a filter provided for an operating one of said frequency dividers.

A frequency switching method comprising the steps of:

• generating signals having different frequencies;
• dividing a frequency of one of the signals by a dividing factor to produce a divided signal;
• combining the divided signal with the other signals to generate a single output signal;
• selecting from the single output signal a component having a frequency equal to a frequency obtained in the dividing step;
• wherein
• the step of dividing includes the step of controlling a plurality of frequency dividers so that one of the frequency dividers is in an active mode in which frequencies of input signals are divided and the remaining frequency dividers are in an inactive mode in which frequencies of input signals are not divided.

A frequency switching method comprising the steps of:

• generating a first signal having a fixed frequency of k times as much as a given frequency, where k is an integer equal to or greater than two;
• dividing the frequency of the first signal by a dividing factor k to output a resulting frequency-divided signal;
• generating second signals each having different frequencies from each other;
• mixing the frequency of said frequency-divided signal with the frequency of one of the second signals to generate an output signal;
• selecting a component with a desired local frequency from the output signal generated in the mixing step:
• wherein
• the step of dividing the frequency of the first signal includes the step of controlling a plurality of frequency dividers provided for said respective second signals so that one of said frequency dividers is in an active mode in which the frequency of said first signal is divided to output said frequency-divided signal while the remaining frequency dividers are in an inactive mode in which no signals are output.