This paper presents the measurement results for an analog to digital converter (ADC), which is targeted to operate especially in a video encoding system. It is designed to convert the dc coefficients of a current-mode discrete cosine transform into digital form. The converter is able to change its quantization factor adaptively, fulfilling the demands of several video compression standards. The maximum conversion resolution is 7frac12 bits. The measurements verify correct operation of the converter in terms of input-output behaviour and adaptivity of the quantization