AD converter device and millimeter wave radar system

A millimeter wave radar system comprising:

• a transmission antenna for radiating a transmission wave into the air;
• a plurality of reception antennas for receiving a reflected wave from an object for the transmission wave;
• a high frequency unit for generate a plurality of beat signals by down-converting the reflected wave received by the plurality of reception antennas using the transmission wave;
• a low pass filter for filtering the plurality of beat signals;
• and
• a baseband unit for processing the plurality of beat signals filtered by the low pass filter,
• wherein the baseband unit includes a plurality of MASH type sigma delta AD converters for converting the plurality of beat signals filtered by the low pass filter from analog signals to digital signals respectively;
• wherein each of the MASH type sigma delta AD converters comprises:
• a probe signal generation circuit for generating a probe signal;
• a first modulator including a first analog integrator configured with an analog circuit and a first quantizer for quantizing an addition signal obtained by adding the probe signal and an output signal of the first analog integrator;
• an analog filter for filtering an extraction signal obtained by extracting a quantization error generated in the first quantizer and the probe signal;
• a first AD converter for converting an output signal of the analog filter from an analog signal to a digital signal, the first AD converter operating at an operation frequency lower than an operation frequency of the first modulator;
• a first adaptive filter for searching for a first transfer function which is a transfer function of the first modulator by observing an output signal of the first quantizer in accordance with the probe signal;
• a second adaptive filter for searching for a second transfer function which is a transfer function from an output of the first modulator to the first AD converter via the analog filter by observing an output signal of the first AD converter in accordance with the probe signal;
• and
• a noise cancellation circuit for canceling the quantization error and the probe signal included in the output signal of the first quantizer using the search result of the first adaptive filter and the search result of the second adaptive filter.