We have developed novel compact suspended stripline filters and low-loss passives based on MMIC wafer fabrication techniques and heterogeneous integration through gold-gold compression bonds. The key features are high precision, on-wafer testable for known-good-die, and high electromagnetic isolation. This approach is best suited to designs in the range of 0.5-100 GHz. As an example of applying this novel capability, a 0¬ 11 GHz & 11-22 GHz contiguous diplexer filter was designed and fabricated to produce a SiC center-conductor die which is bonded and suspended in gold-plated silicon ground cavities using heterogeneous integration. EM modeling accurately predicts filter performance and multiple fabricated copies of the filter have near-identical S-parameters characteristics.