Very small, multilayer monolithic microwave integrated circuit (MMIC) couplers are proposed. Novel methods for size reduction, i.e., a quasi-lumped elements approach and a newly developed multilayer coupled-line structure, are also described. A 24-26-GHz-band branch-line coupler and a 20-30-GHz-band broadside coupler were implemented in very small areas of less than 0.4 mm*0.4 mm and 0.2 mm*0.2 mm, respectively. Both couplers used a meanderlike thin-film microstrip line configuration to achieve a drastic size reduction.ETX