Frequency-modulated continuous-wave radar system and frequency tracking method for calibrating frequency gains of a radio frequency signal to approach wideband flatness frequency responses

A frequency-modulated continuous-wave radar system comprising:

• a waveform generator configured to generate a modulation pattern signal;
• a delta-sigma modulation circuit coupled to the waveform generator and configured to modulate the modulation pattern signal for outputting a delta-sigma modulation signal;
• a voltage controlled oscillator coupled to the waveform generator and configured to output a first frequency signal;
• a frequency divider circuit coupled to the delta-sigma modulation circuit and the voltage controlled oscillator and configured to convert the first frequency signal to a feedback low frequency signal according to the delta-sigma modulation signal;
• a control circuit coupled to the voltage controlled oscillator and the frequency divider circuit and configured to control linearity of the voltage controlled oscillator according to the feedback low frequency signal;
• an injection locked oscillator coupled to the voltage controlled oscillator and the waveform generator and configured to convert the first frequency signal to a second frequency signal according to the modulation pattern signal;
• a power amplifier circuit coupled to the injection locked oscillator and the waveform generator and configured to amplify the second frequency signal in order to generate a radio frequency signal according to the modulation pattern signal;
• and
• a first power detection circuit coupled to the voltage controlled oscillator and configured to detect a peak power of the first frequency signal;
• a second power detection circuit coupled to the injection locked oscillator and configured to detect a peak power of the second frequency signal;
• a third power detection circuit coupled to the power amplifier circuit and configured to detect a peak power of the radio frequency signal;
• and
• a calibration engine circuit coupled to the delta-sigma modulation circuit, the voltage controlled oscillator, the injection locked oscillator, the power amplifier circuit, the first power detection circuit, the second power detection circuit, and the third power detection circuit and configured to adjust frequency gains of the voltage controlled oscillator, the injection locked oscillator, and the power amplifier circuit to approach wideband flatness frequency responses according to peak powers of the first frequency signal, the second frequency signal, and the radio frequency signal;
• wherein the first frequency signal has a first frequency, the second frequency signal has a second frequency, and the second frequency is greater than the first frequency.