a fast analog to digital converter to a digital sum value this sum value is added to the preceding digital value stored in a buffer memory and the result is fed to a slow but precise d a converter for generation of the next y value this has the advantage that good results can be obtained with a d converters less expensive than those heretofore required to obtain such results application_number US 7433393 A description in the drawing the input signal for the circuit is a carrier signal with the intermediate frequency if omega of a vhf broadcast receiver which carrier frequency has been modulated with the quantity or function h t namely the broadcast program in accordance with the invention the instantaneous value of input signal y t has added to it in a circuit element 1 a previously stored value y t t the resulting analog sum value is converted in a fast adc analog to digital converter 3 into a digital sum value from this digital sum value a previously stored signal value is deducted since the sum signal is formed from two signals having different signs the sum signal is small relative to the total signal a suitable adc 3 is component ad 9028 made by analog.