Fmcw signal generation circuit

An FMCW signal generation circuit comprising:

• an oscillator configured to oscillate in an oscillation frequency that is variable in accordance with a control signal being input thereto and output an FMCW signal having the oscillation frequency;
• a frequency divider configured to obtain a frequency division signal by frequency-dividing the FMCW signal generated by the oscillator;
• a digital phase detector configured to obtain a phase value by detecting a phase of the frequency division signal;
• a first differentiator configured to obtain a frequency by differentiating the phase value:
• a second differentiator configured to obtain a frequency variation rate by differentiating the frequency obtained by the firs differentiator;
• a subtractor configured to calculate a difference between a set frequency variation rate that is set at a given value and the frequency variation rate:
• a DA converter configured to convert the difference calculated by the subtractor into an error signal having analog value;
• and
• an integrator configured to generate the control signal for the oscillator by integrating the error signal,
• werein the first differentiator, the second differentiator, and the subtractor are configured as digital circuits.

An FMCW signal generation circuit comprising:

• an oscillator configured to oscillate in an oscillation frequency that is variable in accordance with a control signal being input thereto and output an FMCW signal having the oscillation frequency;
• a frequency divider configured to frequency-divide the FMCW signal generated by the oscillator;
• a digital phase detector configured to obtain a phase value by detecting a phase of the FMCW signal being frequency-divided by the frequency divider;
• a first differentiator configured to obtain a frequency by differentiating the phase value;
• a second differentiator configured to obtain a frequency variation rate by differentiating the frequency;
• a comparator configured to compare and determine whether the frequency is higher than a first set frequency and whether the frequency is lower than a second set frequency that is lower than the first set frequency;
• a selector configured to select an absolute value of a second set frequency variation rate that is set at a negative value when the frequency is higher than the first set frequency and select a first set frequency variation rate that is set at a given positive value when the frequency is lower than the second set frequency;
• a subtractor configured to calculate an error that is a difference between the first set frequency variation rate or the absolute value of the second set frequency variation rate selected by the selector and an absolute value of the frequency variation rate;
• and
• an integrator comprising a fixed capacitor, a first DA converter, and a second DA converter, the integrator being configured to generate the control signal for the oscillator,
• wherein the second DA converter causes a current that is proportional to the error to flow out of the fixed capacitor when the frequency is higher than the first set frequency, and
• wherein the first DA converter causes a current that is proportional to the error to flow into the fixed capacitor when the frequency is lower than the second set frequency.