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Nexxim Simulator >
Nexxim Component Models >
Nexxim Filters >
Raised Cosine Low Pass Filter

Raised Cosine Low Pass Filter

Netlist Syntax

An instance of a raised cosine low pass filter has the following Nexxim netlist syntax:

Axxx n1 n2 [FC=val] [E=val] [B=val] [R1=val] [R2=val] [IL=val] COMPONENT=raised_cosine_low_pass_filter

n1 and n2 are the nodes connected to the filter. The entry COMPONENT=raised_cosine_low_pass_filter is required.

**Raised Cosine Low Pass Filter Instance Parameters**
Parameter	Description	Units	Default
FC	Cutoff frequency	Hz	1e9
E	Exponential parameter	None	0.5
B	Rolloff factor	None	0.25
R1	Reference resistance for node 1	Ohm	50
R2	Reference resistance for node 2	Ohm	50
IL	Insertion loss	dB	0

Netlist Example

A22 1 2 FC=80e6 E=0.5 B=0.25 R1=50 R2=50 IL=0
+ COMPONENT=raised_cosine_low_pass_filter

Notes

1. The raised cosine frequency characteristic is given by:

where T is the symbol interval and b (parameter B) is the rolloff factor, which takes values ranging from 0 to 1.

2. The bandwidth occupied by the signal beyond the Nyquist frequency 1/2T is called the excess bandwidth and is usually expressed as a percentage of the Nyquist frequency. For example, when B=0.5, the excess bandwidth is 50%, and when B=1.0, the excess bandwidth is 100%.

3. The exponential parameter E raises the transfer function to the power E: H_FRC(jw)=(H_RC(jw))^E. The default value E=0.5 is typically used in a cascade of identical transmit and receive filters.

4. At DC, the filter is implemented as a short circuit.

Reference

1. G. Proakis, Digital Communications, McGraw-Hill, 1989

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