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Amplifier (Obsolete RF System Amplifier)

Symbol

Note

2003C introduces an improved version of Amplifier: Amplifier2. Please use Amplifier2 for new designs; refer to Amplifier2 documentation for more information.

Available in ADS

Parameters

Name

Description

Units

Default

S21

Forward transmission gain (real or complex number; refer to note 2)

None

None

S11

Port 1 reflection (real or complex number; refer to note 2)

None

None

S22

Port 2 reflection (real or complex number; refer to note 2)

None

None

S12

Reverse transmission gain (real or complex number; refer to note 2)

None

None

NF

Input noise figure

dB

None

NFmin

Minimum noise figure at Sopt

dB

None

Sopt

Optimum source reflection for NFmin

None

None

Rn

Equivalent noise resistance

None

None

Z1

Reference impedance for port 1 (real or complex number)

None

None

Z2

Reference impedance for port 2 (real or complex number)

None

None

ClipDataFile

Clip data beyond maximum input power: NO to disable; YES to enable

None

NO

ImpNoncausalLength

Non-causal function impulse response order

Integer

None

ImpMode

Convolution mode

Integer

None

ImpMaxFreq

Maximum frequency to which device is evaluated

None

None

ImpDeltaFreq

Sample spacing in frequency

None

None

ImpMaxOrder

Maximum allowed impulse response order

Integer

None

ImpWindow

Smoothing window

Integer

None

ImpRelTol

Relative impulse response truncation factor

None

None

ImpAbsTol

Absolute impulse response truncation factor

None

None

Range of Usage

NF ≥ 0 dB
NFmin > 0
0 < | Sopt | < 1
0 < Rn
GainCompFreq > 0
For S21 = mag/ang
|S21| > 0

Gain Compression Parameters

Name

Description

Units

Default

GainCompType

Gain compression type:

None

None

GainCompFreq

Reference frequency for gain compression (if gain compression is described as a function of frequency)

None

None

ReferToInput

Specify gain compression with respect to input or output power of device

None

None

SOI

Second order intercept

dBm

None

TOI

Third order intercept

dBm

None

Psat

Power level at saturation

dBm

None

GainCompSat

Gain compression at Psat

dB

None

GainCompPower

Power level in dBm at gain compression for X dB compression point, specified by GainComp

dBm

None

GainComp

Gain compression at GainCompPower

dB

1

AM2PM

Amplitude modulation to phase modulation

deg/dB

None

PAM2PM

Power level at AM2PM

dBm

None

GainCompFile

Filename for gain compression data in S2D file format

None

None

Range of Usage for Gain Compression Parameters

When specifying gain compression using model parameters, only certain combination of parameters will produce stable polynomial curve fitting. The recommended parameter combinations are listed here.

Note If unrealistic parameter values are used, the polynomial will become unstable, resulting in oscillations.

  • Third-order intercept and 1dB gain compression parameters:
    TOI, GainCompPower with GainComp=1dB
    Range of validity: TOI > GainCompPower + 10.8
  • Third-order intercept and power saturation parameters:
    TOI, Psat, GainCompSat
    Range of validity: TOI > Psat + 8.6
  • 1dB gain compression and power saturation parameters:
    GainCompPower with GainComp=1dB, Psat, GainCompSat
    Range of validity: Psat > GainCompPower + 3
  • Third-order intercept, 1dB gain compression and power saturation parameters:
    TOI, GainCompPower with GainComp=1dB, Psat, GainCompSat
    Range of validity: Psat > GainCompPower +3, TOI > GainCompPower + 10.8
  • Second-order intercept and third-order intercept parameters: SOI, TOI
  • AM to PM with 1dB gain compression parameters:
    AM2PM, PAM2PM, and GainCompPower with GainComp=1dB
    The value for AM2PM must satisfy this condition to avoid a square root of a negative number:

  • AM to PM with third-order intercept parameters:
    AM2PM, PAM2PM, and TOI
    The value for AM2PM must satisfy this condition to avoid a square root of a negative number:

    If SOI is not specified, the amplifier is modeled using a polynomial of odd orders:
    y = a1 × x + a3 × x3 + a5 × x5 + . . . .
    As a result, only odd order harmonics (m × f, where m is an odd number) and odd order intermods (m × f1 + n × f2, where m+n is an odd number) are taken into account.
    If SOI is specified, the amplifier polynomial has an even order term:
    y = a1 × x + a2 × x2 + a3 × x3 + a5 × x5 + . . . .
    As a result, both odd and even order harmonics and intermods are taken into account in the simulation.

Warning Messages

When values for TOI, 1 GainCompPower, and Psat are properly related, the DC input-output transfer characteristic has the form shown in DC Input-Output Transfer Characteristics.

  • No Saturation. A warning is displayed if a polynomial is generated that does not have a maximum where the transfer characteristics can be clipped (when the amplifier cannot reach saturation). Refer to No Saturation Warning.

The result of this specification is that the saturated output is lower than the output at the 1 dB compression point, and the input-output characteristics have a non-monotonic characteristic transfer curve.

DC Input-Output Transfer Characteristics

No Saturation Warning

Non-Monotonic Transfer Curve Warning

Notes/Equations
  1. If NFmin, Sopt, and Rn are used to characterize noise, the following relation must be satisfied for a realistic model.

    A warning message will be issued if Rn does not meet this criterion. If the noise parameters attempt to describe a system that requires negative noise (due to Rn being too small), the negative part of the noise will be set to zero and a warning message will be issued.
  2. Use the function polar(mag,ang), or dbpolar(dB, ang), or VSWRpolar(VSWR, ang) to convert these specifications into a complex number.
  3. For an S-parameter or a noise figure sinusoidal ripple, use the function ripple (mag, intercept, period, variable); for example ripple(0.1, 0, 10 MHz, freq).
    example: S21=dbpolar(10+ripple( ),0.)
  4. When you define the gain using S21, keep in mind that this gain is applied to the forward incident wave into the input of the amplifier. This is in keeping with the measurement standards used to define amplifier gain at a system level. This means that if you change S11 from 0 to 0.9 for example, you will see no change in output power because the reflect wave is not taken into account by the amplifier's definition of gain, only the incident wave.
  5. Z1 and Z2, the reference impedance parameters for ports 1 and 2, are used in conjunction with the parameters S11/S21/S12/S22. This is because S-data is always used with respect to a particular reference impedance.
  6. This model blocks dc.
  7. For circuit envelope simulation, baseband signals are blocked.
  8. OmniSys used GComp1-GComp7 data items for specifying gain compression. Gain Compression Data for OmniSys and ADS summarizes the gain compression data for OmniSys and ADS. Refer to OmniSys Parameter Information for OmniSys parameter information.

GComp1-GComp6 can be specified by using the corresponding ADS gain compression parameters and setting GainCompType=LIST. Or, they can also be contained in an S2D format setting GainCompType=FILE. Also note that an S2D file could contain other data such as small signal S-parameters and noise; these data are ignored by the RF System Amplifier.

OmniSys

ADS

GComp1: IP3

TOI

GComp2: 1dBc

GainComp=1dB
GainCompPower

GComp3: IP3, 1dBc

TOI
GainComp=1dB
GainCompPower

GComp4: IP3, Ps, GCS

TOI
Psat
GainCompSat

GComp5: 1dBc, Ps, GCS

GainComp=1dB
GainCompPower
Psat
GainCompSat

GComp6: IP3, 1dBc, Ps, GCS

TOI
GainComp=1dB
GainCompPower
Psat
GainCompSat

GComp7

GainCompType=FILE
GainCompFile=filename 

OmniSys Parameter Information
  1. The AM to PM option uses parabolic amplitude dependence to describe the amplitude to phase modulation conversion. When a signal of type Vin(τ)=ACos(Wφ), is applied to the input of a device with parabolic AM to PM, the output phase exhibits:

    Therefore, this phase depends on the input signal amplitude A in a parabolic manner. Because the conversion of amplitude to phase is amplitude dependent, the AM to PM (AM2PM) is specified in degrees per decibel at a given output power (PAM2PM). k is calculated from these two parameters.

    When AM to PM is specified, the third-order intermod and gain compression are side effects. If AM2PM is specified to be very large compared to the third-order intercept or gain compression, a warning is issued.
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