Systems, devices, and methods related to phase shifters are provided. An example true time-delay (TTD) phase shifter structure includes a signal conductive line disposed on a first layer of the structure; a first switchable ground plane comprising a first conductive plane disposed on a second layer of the structure; a second switchable ground plane comprising a second conductive plane disposed on a third layer of the structure, where the first, second, and third layers are separate layers of the structure; a first switch coupled between the first switchable ground plane and a first ground element, the first ground element disposed on the second layer; and a second switch coupled between the second switchable ground plane and a second ground element, the second ground element disposed on the third layer.