Multiple PLL oscillator and multiple CW radar used therefore

A vehicle on which a multiple millimeter CW radar and an active cruise controller for controlling driving of the vehicle by using information detected by the multiple millimeter CW radar are mounted,

• wherein said multiple millimeter CW radar comprises:
• a multiple PLL oscillator;
• a transmitting antenna radiating a millimeter wave signal of an oscillation output of said multiple PLL oscillator into the space;
• a receiving antenna receiving a signal reflected by a subject, of said radiated millimeter wave signal;
• a mixer for mixing the millimeter wave signal obtained from said receiving antenna with an output of said multiple PLL oscillator;
• and
• a signal processing circuit processing an output of said mixer and detecting position information and/or speed information of said subject, and
• said multiple PLL oscillator being an oscillator for oscillating and outputting a plurality of frequencies having a predetermined step frequency, comprising:
• first and second reference frequency sources;
• a switch for selecting one of outputs of said first and second reference frequency sources alternatively and at predetermined time interval;
• and
• a PLL frequency synthesizer generating a millimeter wave oscillation output corresponding to each of said first and second reference frequency sources,
• wherein said PLL frequency synthesizer comprises:
• a phase comparator for comparing a phase of output signal of a frequency divider with a phase of a signal of the reference frequency source selected by said switch;
• a low pass filter smoothing the output of the phase comparator;
• a voltage controlled oscillator controlled by an output of said low pass filter;
• a mixer for mixing an output of said voltage controlled oscillator with an output of a locked reference frequency source;
• an output unit for outputting an upper side band frequency signal of said mixer as an output of the multiple PLL oscillator;
• and
• a feedback unit for inputting an output of a lower side band frequency signal of said mixer to said frequency divider;
• and
• the frequency difference of said first and second reference frequency sources is equal to a frequency obtained by dividing frequency of the lower side band frequency signal of said mixer by the dividing number of said frequency divider.

A multiple PLL oscillator for oscillating and outputting a plurality of frequencies having a predetermined step frequency, comprising:

• a first and a second reference frequency sources;
• a switch for selecting the ore of outputs of said first and said second reference frequency sources alternatively and at predetermined time interval;
• and
• a PLL frequency synthesizer generating a millimeter wave oscillation output corresponding to each of said first and second reference frequency sources,
• wherein said PLL frequency synthesizer comprises:
• a phase comparator for comparing a phase of output signal of a frequency divider with a phase of a signal of the reference frequency source selected by said switch;
• a low pass filter smoothing the output of the phrase comparator;
• a voltage controlled oscillator controlled by an output of said low pass filter;
• a mixer for mixing an output of said voltage controlled oscillator with an output of a locked reference frequency source;
• an output unit for outputting an upper side band frequency signal of said mixer as an output of the multiple PLL oscillator;
• and
• a feedback unit for inputting an output of a lower side band frequency signal of said mixer to said frequency divider, and
• the frequency difference of said first and second reference frequency sources is equal to a frequency obtained by dividing frequency of the lower side band frequency signal of said mixer by the dividing number (N) of said frequency divider.