Mixer (First RF System Mixer, Polynomial Model for Nonlinearity)
Symbol
Available in ADS
Parameters
Name 
Description 
Units 
Default 

SideBand 
Produce UPPER, LOWER, or BOTH sidebands at output port 
None 
UPPER 
ImageRej 
Image rejection at output with respect to fundamental 
dB 
None 
LO_Rej1 
LO to Input Port Rejection 
dB 
None 
LO_Rej2 
LO to Output Port Rejection 
dB 
None 
RF_Rej 
Input to Output Port Rejection 
dB 
None 
ConvGain 
Conversion Gain, use x + j × y, polar(x,y), dbpolar(x,y) for complex value; see note 2) 
None 
dbpolar(0,0) 
S11 
Forward Reflection Coefficient, use x + j × y, polar(x,y), dbpolar(x,y), vswrpolar(x,y) for complex value; see note 2) 
None 
polar(0,0) 
S22 
Reverse Reflection Coefficient, use x + j × y, polar(x,y), dbpolar(x,y), vswrpolar(x,y) for complex value; see note 2) 
None 
polar(0,180) 
S33 
LO Port Reflection Coefficient, use x + j × y, polar(x,y), dbpolar(x,y), vswrpolar(x,y) for complex value; see note 2) 
None 
0 
PminLO 
Minimum LO Power before starvation 
None 
None 
NF 
Double sideband noise figure 
dB 
None 
NFmin 
Minimum double sideband noise figure at Sopt 
dB 
None 
Sopt 
Optimum source reflection for minimum noise figure, use x + j × y, polar(x,y), dbpolar(x,y) for complex value 
None 
None 
Rn 
Equivalent noise resistance 


Z1 
Reference impedance for port 1 (real or complex number) 


Z2 
Reference impedance for port 2 (real or complex number) 


Z3 
Reference impedance for port 3 (real or complex number) 


ImpNoncausalLength 
Noncausal function impulse response order 
Integer 
None 
ImpMode 
Convolution mode 
Integer 
None 
ImpMaxFreq 
Maximum frequency to which device is evaluated 
None 

ImpDeltaFreq 
Sample spacing in frequency 
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
ConvGain > 0 
Gain Compression Parameters
Name 
Description 
Units 
Default 

GainCompType 
Gain compression type: LIST=use model gain compression specifications; FILE=use filebased gain compression data 
None 
LIST 
GainCompFreq 
Reference frequency for gain compression (if gain compression is described as a function of frequency) 

ReferToInput 
Specify gain compression with respect to input or output power of device 
None 
OUTPUT 
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 
5.0 
GainCompPower 
Power level in dBm at gain compression specified by GainComp 
dBm 
None 
GainComp 
Gain compression at GainCompPower 
dB 
1 dB 
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. Recommended parameter combinations are listed here.
Note If unrealistic parameter values are used, the polynomial will become unstable, resulting in oscillations.
 Thirdorder intercept and 1dB gain compression parameters:
TOI, GainCompPower, with GainComp=1dB.
Range of validity: TOI > GainCompPower + 10.8.  Thirdorder 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, and Psat, GainCompSat.
Range of validity: Psat > GainCompPower + 3.  Thirdorder intercept, 1dB gain compression and power saturation parameters:
TOI, GainCompPower with GainComp=1dB, and Psat, GainCompSat.
Range of validity: Psat > GainCompPower +3, TOI > GainCompPower + 10.8  Secondorder intercept and thirdorder intercept parameters: SOI, TOI.
Notes/Equations
 The Mixer component is similar to Mixer2. The key difference is that Mixer supports frequency conversion AC analysis or FCAC analysis for smallsignal AC or Sparameter analysis, while Mixer2 does not. This capability allows smallsignal frequency traditionally done at only one frequency to be somewhat extended to deal with more than one frequency. In terms of convergence, Mixer2 is typically more robust than Mixer, as the power detection is implemented differently.
 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.  Use the function polar(mag,ang) or dbpolar(dB, ang), or VSWR polar(VSWR, ang) to convert these specifications into a complex number.
 For an Sparameter 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.)  Z1, Z2 and Z3 the reference impedance parameters for ports 1, 2 and 3 are used in conjunction with the parameters S11/S21/S12/S22. This is because Sdata is always used with respect to a particular reference impedance.
 This model passes DC in the sense that a DC source at the RF input passes through the mixer to give a signal at the IF output.
 In harmonic balance simulations, the PminLO parameter sets a threshold for the effect of the LO power on the mixer's conversion gain. The default value of PminLO is 100 dBm. The mixer will provide the expected conversion gain if the LO power is significantly greater (~20 dB) than the value of PminLO. If the LO power is less than this amount, the mixer's conversion gain will deteriorate in a nonlinear fashion.
 Gain compression can be specified by using the gain compression model parameters, or this information can be contained in an S2D format file. All S2D gain compression types are supported by this model. Gain compression types 1 through 6 can also be described using the gain compression model parameters. Gain Compression 7 information must be contained in an S2D file. The GainCompType parameter instructs the model where to look for this datain an S2D file or use model parameters.
For S2D data file format information refer to Working with Data Files.  Mixer operation with the SOI and TOI parameters is described in this note.
First consider an amplifier. Consider two input tones at f1 and f2 (assume f1<f2) and at the same power level. Do a 2tone HB simulation. The output will have firstorder tones at f1 and f2. It also have secondorder intermod products at f2f1 and at f1+f2. It will also have thirdorder intermod products at 2 × f1f2 (will be smaller than f1 by f2 f1) and 2 × f2f1 (will be greater than f2 by f2f1). Drawing a picture of this frequency plan can be helpful. Based on these tones we can calculate the SOI and TOI of the amplifier. The general equation is IPn= (n × P1Pn)/(n1) where P1 is the power level of the firstorder tone and Pn is the power level of the nthorder tone. For SOI, we can use the power levels at f1 and f2f1 or we can use the power levels at f2 and f1+f2. For TOI, we can use the power levels at f1 and 2 × f1f2 or we can use the power levels at f2 and 2 × f2f1.
For a mixer, everything is the same, except that everything is being shifted down (down converting mixer) or up (upconverting mixer) by the LO frequency fLO due to mixing. Therefore, all these frequencies will either have fLO subtracted or added. Note that this means that from an HB point of view, we're calculating SOI off of second and thirdorder intermod products and calculating TOI off of second and fourthorder intermod products. For example, TOI can be calculated from a P1 at f1fLO (second order as far as the HB simulation is concerned) and a Pn at 2 × f1f2fLO (fourthorder as far as the HB simulation is concerned).
Also, note that the mixer must be outputmatched in order to validate SOI and TOI.
For more information about SOI and TOI, refer to the Amplifier2 component documentation.  Frequency Conversion AC (FCAC) analysis requires a single frequency at every node of a circuit. If Sideband=BOTH is specified for Mixer, the simulator will use SideBand=LOWER for FCAC analysis.
 When Mixer is used in Transient analysis for single sideband applications, it is recommended that the user set Sideband=BOTH and insert a highorder filter to suppress the undesired sideband.