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LPF_GMSK (Lowpass Filter, GMSK)

Symbol

Available in ADS and RFDE

Parameters

Name

Description

Units

Default

BT

Bandwidth-Time Product of Gaussian Filter

None

0.3

BitRate

Digital bit rate defining filter bandwidth

kHz

270.833

DelayBits

Number of bits delayed by filter

None

5

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

Range of Usage

0 ≤ Alpha ≤ 1
DelayBits ≥ 1

Notes/Equations/Reference
  1. Refer to Filter Categories.
  2. For information on lowpass filter behavior at DC, refer to Lowpass Filter Behavior at DC.
  3. This filter is unidirectional. Its input impedance is infinite and its output impedance is specified by Zout.
  4. This Gaussian filter is used in the GMSK modulation system.
  5. In the steady-state frequency domain analysis, an ideal frequency-domain response 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 DelayBits is set too small, then the impulse response will be severely truncated and will not accurately reflect the ideal frequency response.
  6. A value of 1.0 will be used internally when DelayBits is set to a value that is less than 1.0.
  7. Accuracy of this model in Transient or Circuit Envelope can be further controlled through the ImpMaxFreq, ImpDeltaFreq, and ImpMaxPts parameters.
  8. This component has no default artwork associated with it.
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