In order to minimize filter roll-off, we start with a quality, highly polished substrate and apply layers of metallization within tight tolerances. Our highly anisotropic ion beam etching process enables us to produce features down to 10 microns. Furthermore, the milling process yields a high consistency from circuit to circuit meaning that whether we produce 1 or 100,000 filters, each one will have consistent filter roll-off characteristics.
Low Pass / High Pass
Low-pass filters are devices that are tuned to pass frequencies below a specified range and reject (attenuate) all frequencies above that specified range. High-pass filters do the same sort of thing as the low pass ones but they reject frequencies below a specified range, but pass anything higher.
Band-Pass / Band-reject
A band-pass filter is a device that passes frequencies within a certain range and rejects all frequencies outside of that range. They are essentially a combination of a high-pass and low-pass filters attenuating all frequencies above and below a specified range. Band-reject filters invert the operation in that they attenuate a specific frequency or range of frequencies but pass anything above or below.
A notch RF filter is essentially a Band-reject or Band-stop filter with a very narrow range of blocked frequencies. The tightness of the bands rejected produces a filter with a very high Q Factor.
Ideally, any kind of filter would have a completely flat passband range in that it would totally attenuate the target frequencies to be blocked and freely pass everything else with no gain or attenuation. The transition between the attenuated frequencies and the passed ones would also be instantaneous. In practice, no filter is capable of this level of perfect performance as each has a small range in which frequencies are attenuated but not rejected. This region is referred to as filter roll-off.
SemiGen offers a range of microwave filters designed per customer specifications to eliminate false signals or harmonics by passing the desired signal or band of signals and rejecting any other signals. We offer several major types.