| 摘要 |
PURPOSE:To change the frequency characteristic in an excellent way and to miniaturize the device by providing an electrode finger forming a depletion layer between electrode fingers on a substrate and controlling the spread of depletion with a negative potential impressed to the electrode. CONSTITUTION:An input electrode 23 is formed on a substrate of a surface acoustic wave device as a normal electrode whose cross width and repetitive period are constant and the electrode finger width and interval are taken as 1/4 of the surface acoustic wave wavelength. Moreover, a field effect electrode 30 comprising a source electrode 31, drain electrodes 32a, 32b and gate electrodes 33a, 33b is formed on the substrate as an output electrode and its electrode finger width and interval are taken as 1/8 of the surface acoustic wave wavelength. The drain electrode 32 and the gate electrode 33 form a depletion layer and an output is extracted from the source electrode 31. A negative bias impressed to the drain electrodes 32a, 32b is changed, a voltage generated to source electrode fingers 31a-31e is changed by a bias voltage so as to change the frequency characteristic of the device in an excellent way. |
