Bessel Lowpass Filter
Model Name	LOWPASS(BESSEL_2) LOWPASS(BESSEL_4) LOWPASS(BESSEL_2_DIGITAL)
Symbol
Generics	Name   Type   Default   Unit   Min   Description   FC   REAL     Hz   >0.0   cut-off frequency   GAIN   REAL   1.0       voltage gain
Ports	Interface   Name   Type/Nature   Description   terminal   INP   ELECTRICAL   controlling terminal   terminal   OUTP   ELECTRICAL   output terminal
Description	The architecture BESSEL_2 realizes a second order analog Bessel lowpass. The architecture BESSEL_4 realizes a fourth order analog Bessel lowpass. The cut-off frequency is FC. The architecture BESSEL_2_DIGITAL realizes a second order digital Bessel lowpass. The cut-off frequency is FC. The sampling frequency is 4*FC.
References	Tietze, U,; Schenk, C.: Halbleiter-Schaltungstechnik. Heidelberg: Springer-Verlag, 2002. Schruefer, E.: Signalverarbeitung. Muenchen, Wien: Carl Hanser Verlag, 1990.
Dependencies	Logical Library   Design Unit/Design Entity   IEEE_proposed   ELECTRICAL_SYSTEMS   IEEE   MATH_REAL
Source	See source code
Example	See test-bench