A semiconductor device is disclosed. The semiconductor device includes: a System on Chip (SoC) die; an integrated passive device (IPD); and a first switch, coupled between the SoC die and the IPD; wherein the IPD and the SoC die are disposed in different wafers and bonded together, and the first switch is controlled to disconnect the IPD from the SoC die when the IPD is under a test; and the first switch is controlled to connect the IPD with the SoC die when the IPD is not under the test. A test system for testing an IPD of a semiconductor device and an associated method are also disclosed.