Saw filter using low-pass configuration and method of providing the same
US5854579A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Aug 25, 1997 |
| Grant date | Dec 29, 1998 |
| Priority date | — |
| Expiry date | Aug 25, 2017 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03H9/6483
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
An acoustic wave resonator filter (10) provides series and shunt resonator elements (22, 24) in a ladder network. The series elements (22) are configured in a lowpass configuration. The shunt elements (24) act as impedance inverters in a passband of the filter and they series resonate at an antiresonant frequency of the series elements (22) in a stopband which provides additional isolation. The electrodes (14) of the elements (22, 24) are of a metal thickness which improve the losses of a series resonant frequency in a passband which improves insertion loss. However, any increase in loss near the antiresonant frequency is compensated by the reduced loss near the resonant frequency of the shunt elements (24). The lowpass configuration and the aligned series element antiresonant frequency and shunt element resonant frequency provides good insertion loss, good isolation between transmitting and receiving bands, and maintains good stopband characteristics while reducing the number of elements required for the ladder network.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.