An analog-to-digital converter for an adiabatic logic circuit, including at least one variable-capacitance cell, the cell including first and second main terminals and at least one control terminal insulated from its first and second main terminals and capable of receiving a control voltage to vary the capacitance between its first and second main terminals between a low value and a high value, wherein: the cell has its first main terminal coupled to a node of application of a variable periodic converter power supply voltage; the cell has its second main terminal coupled to a node for supplying a binary output signal of the converter; and the cell receives on its first control terminal an analog input voltage of the converter.