HPF_RaisedCos (Highpass Filter, Raised-Cosine)
Symbol
Available in ADS and RFDE
Parameters
Name |
Description |
Units |
Default |
|---|---|---|---|
Alpha |
Rolloff factor defining filter excess bandwidth, 0 ≤ Alpha ≤ 1 |
None |
0.35 |
SymbolRate |
Digital symbol rate defining filter bandwidth |
kHz |
24.3 |
DelaySymbols |
Number of symbols delayed by filter |
None |
5 |
Exponent |
Exponent factor ( 0 ≤ Exponent ≤ 1 ), to provide for Root Raised-Cosine filter |
None |
0.5 |
DutyCycle |
Pulse duty cycle in percent, used for sinc(x) correction |
None |
0 |
SincE |
Flag to include the Exponent factor on the sinc(x) correction: yes or no |
None |
no |
Gain |
Gain factor |
None |
1.0 |
Zout |
Output impedance |
Ohm |
50 |
WindowType |
Window type applied to impulse response: 0=None, 1=Hann, 2=Hamming |
None |
0 |
ImpMaxFreq |
Maximum frequency to consider when calculating impulse response |
|
|
ImpDeltaFreq |
Frequency sample spacing when calculating impulse response |
|
|
ImpMaxPts |
Maximum number of points in impulse response |
None |
None |
Other |
Output string to netlist |
None |
None |
Range of Usage
0 ≤ Alpha ≤ 1
DelaySymbols ≥ 1
0 ≤ Exponent ≤ 1
0 ≤ DutyCycle ≤ 100
Notes/Equations
- Refer to Filter Categories.
- This filter is unidirectional; input impedance is infinite; output impedance is specified by Zout.
- This filter is unidirectional; input impedance is infinite; output impedance is specified by Zout.
- Voltage gain is described by the following function.
where:Gfilt
= 0.0 for frequency ≤ 0.5 × (1 − Alpha ) × SymbolRate
= 1.0 for frequency ≥ 0.5 × (1 + Alpha ) × SymbolRate
= [0.5 × (1 + sin[π × ( frequency − SymbolRate /2)/
Gcomp
= 1.0
if DutyCycle =0
= [0.01 × DutyCycle × sinc(x)]Exponent
if SincE = YES
= [0.01 × DutyCycle × sinc(x)]
if SincE = NO
sinc(x)
= sin(x)/x
x
= 0.01 × DutyCycle × π × frequency / SymbolRate
- While Exponent can be any value, the standard value is 1.0 for the ideal raised-cosine filter response or 0.5 to simulate the root raised-cosine filter response when present at both the receiving and transmitting channels.
- In steady-state frequency-domain analyses, the ideal frequency-domain response described previously is used; however, this ideal response has an infinite duration impulse response that must be approximated for time-domain simulations in either Transient or Circuit Envelope. If DelaySymbols is set too small, then the impulse response will be severely truncated and will not accurately reflect the ideal frequency response.
Using a Hanning window (WindowType=1) a DelaySymbols value of 15 should result in equivalent frequency domain sidelobes of −90dBc or smaller. - Accuracy of this model in Transient or Circuit Envelope can be further controlled through the ImpMaxFreq, ImpDeltaFreq, and ImpMaxPts parameters.
- The filter can include gain equalization to compensate for duty cycle roll-off. If DutyCycle = 0.0, then no compensation will be applied. If SincE=YES, Exponent will be applied to the gain compensation term, Gcomp. The Exponent term is always present in the Gfilt term.
- This component has no default artwork associated with it.