We have examined the properties of a trilayer high-temperature superconductor (HTS)/insulator/HTS structure and incorporated this structure with multilayer Josephson ramp edge junctions to form a SQUID with a ground plane. The lower and upper Y1Ba2Cu3Ox (YBCO) films in the trilayer structure showed zero-resistance temperatures of 89 K and 85 K respectively. A directly coupled ground-planed SQUID using ramp edge Josephson junctions with a normal barrier layer Pr1Ba2Cu3Ox (PBCO) Showed a voltage modulation of 30 mu V at 9 K and operated up to 50 K.