Abstract: For converting a high-frequency analog signal, which is modulated by a modulation signal, an analog-to-digital converter circuit included a first analog-to-digital converter which is preceded by an amplifier having controllable gain, and which is followed by a controllable divider. A quantization unit generates control signals from the analog input signal for setting the gain of the controllable gain amplifier and for setting the divisor of the controllable divider. The quantization unit includes a second analog-to-digital converter which digitizes the analog input signal a rate approximately corresponding to the sampling rate of the first analog-to-digital converter. The second analog-to-digital converter is followed by a rectification unit which rectifies the signal digitized by the second converter. The rectification unit is followed by a coder which generates an output which increases with increasing momentary amplitude of the rectified signal.