This paper reports on the development of a micromachined parallel‐plate tunable capacitor with a wide tuning range. Different from conventional two‐parallel‐plate tunable capacitors, this tunable capacitor consists of one suspended top plate and two fixed bottom plates. One fixed plate and the top plate form a variable capacitor, while the other one provides necessary electrostatic actuation. Among the fabricated prototype devices, a maximum controllable tuning range of 69.8%@1 MHz has been obtained experimentally, exceeding the theoretical limit (50%) of conventional two‐parallel‐plate tunable capacitors. A component quality factor (Q) of 30@5 GHz and a self‐resonant frequency far beyond 5 GHz have been achieved. The fabrication process is compatible with the existing standard IC (integrated circuit) technology, which makes it suitable for integrated wireless communication applications. © 2001 John Wiley & Sons, Inc. Int J RF and Microwave CAE 11: 322–329, 2001.