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BPF_PoleZero (Bandpass Filter, Pole Zero)

Symbol

Available in ADS and RFDE

Parameters

Name

Description

Units

Default

Numerator

List of numerator coefficients

None

list(1)

Denominator

List of denominator coefficients

None

list(1,1.4,1)

Gain

Gain factor

None

1.0

Fcenter

Passband edge frequency

GHz

1

BWpass

Passband edge-to-edge width

GHz

1.0

StopType

Stopband input impedance type: OPEN or SHORT

None

open

Z1

Input port reference impedance

Ohm

50

Z2

Output port reference impedance

Ohm

50

Notes/Equations
  1. This is an S-domain filter.
  2. Denominator and Numerator are a list of polynomial coefficients.
    The transfer function for the filter is:

    where
    S = j ×  (Freq/Fo − Fo /Freq)/(Fhigh/Fo − Fo /Fhigh )
    and
    Freq is the analysis frequency
    Fhigh = Fcenter + 0.5 × BWpass
    Fo = sqrt((Fcenter − 0.5 × BWpass) × (Fcenter + 0.5 × BWpass))
  3. The following example demonstrates interpretation of simulation results with this component. From the user-specified poles/zeros, we derive:
    S21_Lowpass_Prototype= Gain*[(s-Z1)*...*(s-Zn)]/[(s-P1)*...(s-Pm)]
    We then check to see if S21_Lowpass_Protope is > 1. If yes, we scale S21 by a another factor to make sure S21_Max1 . We then derive S11 (S22) from the following formula:
    S112 + S212 = 1
    In this example, when Gain is set > 0.471151, then S11 is derived as what you will expect. If Gain in your example is < 0.471151, then S11 derived from the preceding equation, will be much higher that what you will expect. In this situation, set Gain to be 0.1 so that S21 has a lot of insertion loss. But we assumed there is no insertion loss in deriving S11.
    There are other alternatives:
    • Use S2P_Eqn so that you can define the S21 and S11 polynomials however you want. You can define this as follows:
      s=j ω , S21=Gain*(s-Z1)*...*(s-Zn)/(s-P1)*...*(s-Pn), S11=<your choice>
    • Use BPF_Pole_Zero to model a lossless BPF, then use an attenuator to add insertion loss.
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