A wideband and compact quadrature coupler intended for 5G applications is presented. The circuit is integrated using a dedicated cost-effective three-dimensional (3-D) technology and is implemented from a 3-D transformer along with Metal-Insulator-Metal (MIM) capacitors that ensure a very good compactness. The coupler's area does not exceed 0.11 mm 2. The measurements show good performance over a bandwidth of 7GHz ranging from 19.5GHz to 26.5GHz. Within this whole band, insertion losses remain better than 0.6dB whereas a phase difference between both outputs of 90° is achieved with a maximum deviation of 3°.