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BPF_RaisedCos (Bandpass Filter, Raised-Cosine)

Symbol

Available in ADS and RFDE

Parameters

Name

Description

Units

Default

Alpha

Rolloff factor defining filter's excess bandwidth, 0 ≤ Alpha ≤ 1

None

0.35

Fcenter

Passband center frequency

GHz

1.5

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

Impulse sample spacing in frequency

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
  1. Refer to Filter Categories.
  2. This filter is unidirectional; input impedance is infinite; output impedance is specified by Zout.
  3. Voltage gain is described by the following function.

    where

    Gfilt

    = 1.0 for Freq ≤ 0.5 × (1 − Alpha ) × SymbolRate

     

     

    = 0.0 for Freq ≥ 0.5 × (1 + Alpha ) × SymbolRate

     

     

    = [0.5 × (1 − sin[π × ( FreqSymbolRate /2)/

     

    G comp

    = 1.0

    if DutyCycle =0

     

    = [0.01 × DutyCycle  × sinc(x)]Exponent

    if SincE = YES

     

    = [0.01 × DutyCycle  × sinc(x)]

    if SincE = NO

    Freq

    = abs ( Fcenterfrequency )

     

    sinc(x)

    = sin(x)/x

     

    x

    = 0.01 × DutyCycle × π × Freq / SymbolRate

     

  4. 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.
  5. 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 accuraely reflect the ideal frequency response.
    Using a Hanning window (WindowType=1) a DelaySymbols parameter of 15 should result in equivalent frequency domain sidelobes of −90dBc or smaller.
  6. Accuracy of this model in Transient or Circuit Envelope can be further controlled through the ImpMaxFreq, ImpDeltaFreq, and ImpMaxPts parameters.
  7. 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.
  8. This component has no default artwork associated with it.
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