Filters

Filter Response

A .Uvitech Ltd. designs and manufactures filters with various amplitude shapes, phase, and group delay response. The majority of the filters are designed to one of the following responses:

Input Impedance

The impedance measured at the input terminal of a filter when it is properly terminated at its output. Insertion Loss The loss of signal caused by a filter being inserted into a circuit and measured in decibels. In general, it is the ratio of power delivered to the load with a filter in the circuit to the power
in the load if a perfect lossless matching transformer replaced the filter.
A .Uvitech maintains insertion loss values from DC to 90% of center frequency for low pass filters, and from 110% of center frequency to maximum spurious-free frequency for high-pass filters (Figures 1 and
2) and at center frequency, or for the full pass band for band-pass filters.

Center Frequency

The arithmetic mean frequency
is called center frequency (F0).
It is calculated using the
1 or 3 dB relative band
edges (F1 and F2)
as ( ) 2 1 F0 = F1+F2/2,
where F1 and F2 are
lower and upper frequencies
at which a particular signal
attenuation occurs (see Figure 3).


Cutoff Frequency (Fc)

The cutoff frequency (Fc) is
the upper passband edge in
low-pass filters or the
lower passband edge in high-pass
filters.
A .Uvitech normally uses the
point at which the attenuation
has relative 1 or 3 dB loss.
This point is usually called the relative
1 or 3 dB point (Figures 1 and 2).


High-Pass Filter

A filter that passes high frequencies and rejects low frequencies. Input Impedance The impedance measured at the input terminal of a filter when it is properly terminated at its output.

Attenuation

Loss of signal through a filter during transmission; measured in decibels (dB).


Bandwidth

The width of the pass band of a
band-pass
filter is the frequency difference
between lower and upper corner
frequencies,
such as 1 or 3 db points.