Filter Specifications

Poles

The number of poles specified determines a filter's pass-band characteristics. A two-pole monolithic crystal filter (MCF), a basic building block, may be cascaded to produce four, six and eight or more poles with additional coupling capacitances interspersed.

Nominal Frequency

The Nominal Frequency of a filter is the centre frequency (F0) or carrier frequency (Fc) in SSB filters.

Pass Bandwidth

Stated in kHz, the Pass Bandwidth refers to the frequency bands where attenuation is equal to or lower than the specified attenuation (in dB)

Stopband

In kHz, the Stop Bandwidth is where attenuations are equal to or larger than the specified figures (dB)  

Ripple

Ripple is the difference (dB) between maximum and minimum attenuation within the passband.

Insertion Loss

Insertion Loss is the loss (dB) defined by the logarithmic ratio of power transmitted to load before and after insertion of the filter.

Guaranteed Attenuation

Attenuation guaranteed (dB) at the specified frequency range.

Spurious

Spurious refers to the attenuation (dB) caused by extraordinary response in the stopband.

Group-Delay Distortion

The difference between maximum and minimum group delay with the passband is referred to as Group Delay Distortion.

Terminating Impedance

Refers to either of the impedances presented to the filter by the source or by the load and describes the resistive portion (Rt) and the parallel capacitive portion (Ct) including stray capacitance.

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