An integrated microwave circuit with a series array of 1440 Josephson tunnel junctions has been developed. This array provides microwave-induced quantized reference voltages between 0.1 and 1.3 V. A comparison of an array voltage with that of a Weston cell shows that a reproducibility of a few parts in 10¹⁰ can be reached for a 1V reference voltage at room temperature. No current dependence of a quantized array voltage has been found within an uncertainty of ± 7 × 10^-13 V from a comparison of two array voltages.