The invention provides a circuit device, an oscillator, electronic equipment, a mobile body capable of achieving both improvement in the frequency accuracy and reduction in the power consumption. The circuit device includes: an A/D conversion part (20) that performs A/D conversion of a temperature detection voltage (VTD) from a temperature sensor part (10), and outputs temperature detection data (DTD; a processing part (50) that performs temperature compensation processing of an oscillation frequency on the basis of the temperature detection data (DTD); and an oscillation signal generation circuit (140) that has a D/A conversion part (80) and an oscillation circuit (150), and generates an oscillation signal (SSC) by using frequency control data (DDS) from the processing part (50) and a vibrator (XTAL). The D/A conversion part (80) includes: a modulation circuit (90) that receives the frequency control data (DDS) of (n+m) bits, and modulates n-bit data on the basis of m-bit data of the frequency control data (DDS); a D/A converter (100) that performs D/A conversion of the modulated n-bit data; and a filter circuit (120) that smooths an output voltage of the D/A converter (100).