Abstract: Quantum voltage standards based on high-temperature superconductor Josephson junctions maintain minimal uncertainty with low operating costs and reduced deployment complexity, which is ideal for in-situ voltage metrology in specialized environments including aerospace and nuclear power applications. This paper presents two coplanar-waveguide-based high-temperature superconductor Josephson junction arrays fabricated on lanthanum strontium aluminum tantalate (LSAT) bicrystal substrates. The first array of 2 serial Josephson junctions generated a quantum voltage step of 39.4 μV under 18.13 GHz microwave coupling with 3 dBm power. The second array of 4 serial junctions produced a 202.5 μV quantum voltage step under 19.42 GHz microwave excitation at 2 dBm. Experimental results demonstrated that the 2-junction array produced only higher-order quantum voltage steps under specific parameter configurations. Through microwave frequency sweep characterization, it was observed that the two-junction array exhibited a broader operational parameter range for generating quantum voltage steps compared to its four-junction counterpart, accompanied by enhanced step width. Systematic investigations confirmed that significant critical current variations among junctions, while permitting individual quantum voltage step generation in each junction, reduced the overlapping region of bias currents required for synchronized operation. The mismatched critical currents consequently diminished the collective quantum voltage step width.