RF Wizard Operation       

                                                                                                                                                                                                


Contents:

INTRODUCTION:

DATA INPUT:

Manual
File           

NARROW BAND DESIGN:

Operating Gain Method
Available Gain Method
Unilateral Gain Method

LOW NOISE DESIGN:

Available Gain Method
Unilateral Gain Method

            WIDE BAND DESIGN:

            P.A. LOAD LINE DESIGN: 

DESIGN TOOLS:

                        Γ to Z Converter
                                                                       
  Series to Parallel Transformer (Constant Q)
                                    Impedance Transformer
                              
Impedance Matcher
                                   
PAD Designer
                                   
MicroStrip Stub Designer
                                    BJT Common-Emitter Amplifier Designer
                                    J-FET Common-Source Amplifier Designer
                                    MOSFET Common-Source Amplifier Designer

CALCULATORS:
                              General-purpose Complex Number Calculator
                                    System Noise and Intermodulation Distortion Calculator
                                    Bit Error Rate vs Carrier-to-Noise Ratio Calculator
                                    Reactance Calculator
                                    Zo of MicroStrip track
                                    Width of MicroStrip track

DESIGN DEMOS:

PRINT OUTPUT:

            NOTES:

1. Stability
2. Unilateral Figure of Merit Gain Ratio 
3.
Operating Gain
4.
Available Gain
5.
Unilateral Gain
6. Maximum Available Gain
7.
Maximum Stable Gain

                                

Introduction:

RF Wizard
has been created for RF Designers, Educators, and Students to greatly simplify the normally complex tasks associated with  
R.F. and Microwave Amplifier Design for specific gain and bandwidth. It also simplifies the design of matched interconnection networks
between R.F Sub-systems such as antennas, transmission lines, amplifiers, mixers, etc. Using Smith Charts and utilising a device’s Scattering
Parameter Data, in conjunction with a user-selected design methodology (Available, Operating, or Unilateral Gain), Optimum, Stable Input
and Output Matching Design Solutions are arrived-at in minutes rather than in hours (or even days). The application also supports
Low Noise Design, Wide Band Design and Power Amplifier Design (utilizing the power device's output load-line data).

As its name suggests; the application provides a simple, step-by-step, “wizard” approach in order to simplify the design process.

Data can be input manually or from a Touchstone File.

Smith Chart Plots can be output to a printer

RF Wizard also includes 15 useful Calculators/Design Tools and a number of demonstration design process examples.


 

Data Input (Manual and File)

Data input, either Manual or from File, is initiated from the Matching Designs drop-down menu on the opening form.

Data Input - Manual:

                                           

 Data Input – File (Narrow Band Design Input):                                                                                         

RF Wizard accepts input from Version 1 and 2, 2-Port, Touchstone Files, with the Scattering Parameter Data in Magnitude-Angle,
Decibel-Angle, or Real-Imaginary format. The data is converted to, and displayed in Magnitude-Angle format.

 

NOTE that many S-data files do not adhere to the Touchstone standard and therefore cause problems when being imported into the 
RF Wizard Design Environment. These files can be created by vector network analyzers or circuit analysis programs. Many can be
imported, but when the text contains subtle errors unexpected results occur. To repair these non-standard files, AWR has created a
utility SdataConversion https://awrcorp.com/download/faq/english/questions/touchstone_file_repair.aspx ) which can read and carry
out several health checks and then repair the data.

An example file access is shown below:

                       

After the file is read in, the following form appears. The incoming Scattering Parameter data is tabled. In this example, the Touchstone File contained Noise
Data. This is tabled also. The S-Parameter data is plotted on the accompanying Smith Chart. Also plotted is a series of relevant Port1 and Port2 Stability
Arcs defining potential regions of instability over the device’s frequency range of operation. This is useful in ensuring that the selection Port1 or Port2
impedances to set gain at a particular frequency can avoid possible instability (oscillation) at other frequencies.





In the control panel of the figure above, note that the Port1 and Port2 Reference Impedances have been read in and because Narrow Band Design has been
nominated, the Wide Band Design Panel is disabled.

In the figure below, preliminary data requirements are completed:

·         Generator and Load Impedances are entered manually.

·         A row of S-Parameter data at the frequency of interest is selected (left mouse-button).

·         If designing for Low-Noise, the corresponding row in the Noise Parameters Table
is also selected (left mouse-button), and the Incl. Noise radio button is activated.

Press the Continue button to move to the Narrow Band Design phase:



                                                                          

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Data Input – File (Wide Band Design Input):                                                                                         

In the example below, a different file has been read in. S-Parameters and Stability Arcs have been plotted. The WideBand Design panel is enabled
(NarrowBand Design panel disabled). The data sets for each of the two band-limiting frequencies (f1 – left click, f2 - right click) are selected.



Press the Continue button to move to the Wide Band Design phase:

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Narrow Band Design (Operating Gain Method):


With the Operating Gain Method, "selective mismatching" is applied in the Output Network in order to achieve a required OVERALL GAIN while conjugate
matching is simultaneously applied in the Input Network.

After data is input, either manually or from file, the form below appears:

                                                              


In this (above), we see that the device is Unconditionally Stable, with Rollett's Stability Factor (k), mu, and the Unilateral Figure of Merit Gain Ratio (U)
also provided. Notice that we can choose ONE of Input, and
Output GAMMAS (and/or their conjugates) to be plotted on the SMITH CHART that follows.
(Note: Had the device been assessed as Conditionally Stable, only the Unilateral Gain method would have been available).

In this example, the Operating Gain method is to be employed. To initiate this, activate the Operating Gain radio button on the Design Method Select
control panel.        

The SMITH CHART now appears (below), showing five constant Operating Gain circles (concentric around the point of Maximum Operating Gain of 
13.48 dB), along with the nominated Gammas. Note also, the text windows which provide continuous repeats of the mouse position on the chart 
in terms of Reflection Coefficient ( Γ ), Impedance ( Z ), Q ( = X/R ) and Operating Gain ( Gp(dB)).

(NOTE that Noise Figure values are displayed only for Low-Noise designs involving the Unilateral and Available Gain methods.)

 

 

Note also that Input and Output Stability Circles are not plotted for values of k greater than 1.1 (here, k = 3.286).                                                                                      

Assume that we wish to achieve an Overall Gain of 13dB. Using the mouse, a newGL point is selected and plotted on the 13dB circle (left button click),
and a second point, the corresponding to a new
Gg (joined by a line) also appears (figure below). For each new GL chosen (for a specific overall gain),
the program automatically computes the corresponding
newGG.

This pair of points is assigned a plot number, and the details are listed to the right of the chart. More points can be plotted as required

 



          
          Completion of this phase of the design requires that you passively convert GL to the newGL and GG to the newGG using the Impedance Transformer Tool
          provided via the "Design Tools" menu.



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Narrow Band Design (Available Gain Method):

The SMITH CHART reappears, (below) showing the five required constant Available Gain circles (concentric around the point of Maximum 
Available Gain of 20.13 dB), along with the nominated Gammas. 
The “Gain Window” now continuously displays Available Gain.

With the Available Gain Method, "selective mismatching" is applied in the Input Network, while conjugate matching is simultaneously applied in 
the Output Network in order to achieve a required overall gain.

   


Assume that we wish to achieve an Overall Gain of 20dB. A
new GG point is selected and plotted on the 20dB circle, and a second point, the 
corresponding
newGL (joined by a line) also appears.

     For each newGG chosen (for a specific overall gain), the program automatically computes the corresponding newGL. This pair of points is assigned a plot
     number, and the details are listed to the right of the chart. More points can be plotted as required.
                                                                                          

     As with the Operating Gain example, completion of this phase of the design requires that you passively convert 
GG to the newGG  AND passively match GL
     
to the newGL (again using the Impedance Transformer Tool).



                                                                                   
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  Narrow Band Design (Unilateral Gain Method):

    In this example, a new set of S-Parameters has been employed, such that the device exhibits Conditional Stability with k = 0.8 and regions of potential
    instability defined by the Input and Output Stability Circles.

    Upon accessing the "Design Control" panel, then nominating assorted Gammas, the Smith Chart (below) appears:


    


Note that there are five Constant Input Gain circles (blue) concentric around the point of Maximum Input Gain (G1) of 1.94 dB (coincident with S11*,
if plotted), and five Constant Output Gain circles (red) concentric around the point of Maximum Output Gain (G2) of 1.25 dB (coincident with S22*,
if plotted). Initially, the “Gain Window” displays Port1 gain contribution (blue) until selection, whereupon it switches to Port2 gain (red).
 


 


Assume a 19 dB overall gain requirement. The device itself provides 17.05 dB. The requirement is met by allowing the input and output circuits
to contribute the remaining 1.95 dB.
 
Using the Mouse's Left and Right Buttons respectively, the points
newGG (0.95 dB), and new GL  (1 dB) are selected.

For completion, passively convert GG to the newGG and GL  to the newGL (again using the Impedance Transformer Tool).



                                                                                                                 
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 Low Noise Design:

If manual input is employed, Noise Data must also be entered (below left).

                                                                                 


The familiar "Design Control" panel again appears (above right). Since a device's noise performance is a function of the input circuit, the Available
Gain and Unilateral Gain methods are the only viable choices. For this example, the Available Gain Method is nominated.

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Available Gain Method:
                                                 
The Smith Chart reappears (below) which, in addition to the Available Gain circles, includes a series of Constant Noise Figure circles (black) concentric
around the Minimum Noise Figure value (here, 1.2 dB).


If, for example, the design calls for an overall gain of 19 dB at the lowest possible Noise Figure, then plot 1 (below) will achieve this (N.F. = 1.3 dB).
For completion, passively convert
GG to the newGG and GL to the new GL (again using the Impedance Transformer Tool).


                                      

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Unilateral Gain Method:

Alternatively, if employing the Unilateral Gain Method, the figure below appears:


   
If we, as before, acquire a total of 2 dB from G1 and G2, we will achieve an overall gain of 19 dB at a Noise Figure of approximately 1.35 dB (below).



As before, for completion, passively convert
GG to the new GG and GL to the new GL (again using the Impedance Transformer Tool).


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Wide Band Design:

This design methodology is based on the observation that for bandwidths that are short relative to the overall useful bandwidth of a high-frequency device, its
S21 characteristic variation (and thus Go) is essentially linear and monotonic. If the device is judged to be close to unilateral, G1 and G2 decouple and it may
be possible to independently adjust them at each end of the required bandwidth in order to flatten the overall response. (i.e. G1 + Go + G2 at f1 = G1 + Go + G2 at f2) 

The goal of the following example is a 19 dB flat gain response across a broad bandwidth delineated by the lower and upper frequencies: f1= 2 GHz and f2 = 3 GHz
respectively. The Input and Output networks will compensate for the expected 6 dB/octave gain roll-off in |S21|. 

The Unilateral Design Method is employed.

The necessary Scattering Parameters at both frequencies are provided either manually, or from file.                                                             

Following this, the “Wide Band Design Select” form (below left) displays the Port1, Device and Port2, Unilateral Gains at both frequencies.

                                                               
                                                          

We can see that the device itself (Go) undergoes a 1.18 dB loss across the band. However, it appears that this shortfall can possibly be eliminated by 
manipulation of the input and output circuits.
We may also achieve an extra 2 dB or more, of overall gain at both frequencies, to achieve the target of
19 dB.  For this to succeed, the constant G1 circles resulting from the gain adjustments (above right) must overlap thus providing TWO Generator
Impedances (one chosen) which fulfil the input gain requirements. The same discussion applies to the chosenG2 circles in the output circuit for the
contributing output gain. See the figure below:

Note that the chosen circles overlap asymmetrically (necessary). If we are dissatisfied with the choice of circles, we can return to the previous panel,
and alter the plot parameters to generate new families of circles for consideration.




Consider the overlapping output circles (both 2.5 dB). We see that they are coincident at two points.

Now consider the overlapping input circles (-0.53 and 0.65). We see that they are also coincident at two points. All that is required is to select an input point
(mouse left-click) and a output point (mouse right-click)

Completion of this phase of the design requires that we passively convert GG to the newGG and GL to the newGL with suitable transformation networks
(again using the Impedance Transformer Tool).


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P.A. Load Line Design:


With this method manufacturer-supplied, optimum, load-line-derived, Output Impedance data is input in either parallel (below left)
or equivalent-series form (below right).  

 

                                                                             

 

"Continue" results in the chart:

 

  

The chart displays the newGL and the computed newGG  required to produce this maximum power out.

Completion of the design requires that we passively convert GG to the newGG and GL to the newGL with suitable transformation networks
(again using the Impedance Transformer Tool).

 

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Design Tools:

                                                                      
                                                                                                                 


                                                                
                        

                                                                                    

·         General-purpose Complex Number Calculator:


                                    


                     

                    

 

                                           

 

                                                  

 

                                                  

             

                                              

Design Demos:

A number of “Design Select” panels/forms, pre-primed with data are provided to assist in familiarising the user in the design methods provided.

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Print Output:

Each of the Smith Chart forms has a Print Chart button in the lower right corner. 

 

Notes:


1. STABILITY:     
                   
The device is considered to be UNCONDITIONALLY STABLE if K > 1 AND |D| < 1,  where 
                    K is the Rollett Stability Factor and
D is the Determinant of the Scattering Matrix, S. 
                    Otherwise, stability will be CONDITIONAL upon the ( modified ) Generator and Load Gammas
                    ( reflection coefficients) being situated outside the regions of instability, defined by the Input
                    and Output STABILITY CIRCLES (plotted on the Smith Charts).

2. UNILATERAL FIGURE of MERIT GAIN RATIO ( U ): 
                   
Most microwave transistor amplifiers, are approximately Unilateral, that is, the measured 
                    S-Parameters satisfy |S
12| << |S21|. To decide whether the 2-Port can be treated as
                    Unilateral, a "Unilateral Figure of Merit Gain Ratio" is used, which is essentially a comparison of
                    the Unilateral Gain to the Bilateral Gain under the
same input and output matching conditions.
                    If U is within 10% of unity, the device may be treated as Unilateral.

3. OPERATING GAIN:
                   
Operating Gain is defined as the ratio of the POWER OUT OF THE NETWORK to the
                    POWER INTO THE NETWORK, i.e., G
P = PL / PIN. Operating Gain circles are obtained
                    by varying
GL, while simultaneously varying the Generator End, GG = newGG, to achieve fixed 
                    values of power gain.

4. AVAILABLE GAIN:
                   
Available Gain is defined as the ratio of the MAXIMUM POWER OUT to the MAXIMUM
                    POWER IN, i.e., G
A = PavN / PavG. Available Gain circles are obtained by varying GG, while
                    simultaneously varying the Load End,
GL = newGL, to achieve fixed values of power gain.

5. UNILATERAL GAIN:
                   
A unilateral device has, by definition S12 = 0. Under this condition, a 2-Port network
                    can be broken into THREE sources of gain; G
o, contributed by the device (e.g. transistor)
                    itself, G
1, which is the "gain" achieved by the input circuit, and G2, the "gain" achieved
                    by the output circuit. Thus G
t  = G1 + Go + G2, where G1 and G2 can be configured independently.

6. MAXIMUM AVAILABLE GAIN (MAG):
                 
Gain is maximised when the two-port is simultaneously conjugate matched (GIN = GG* and GOUT = GL*).
                        
The necessary and sufficient condition for simultaneous matching is K ≥ 1, where K is the Rollett Stability
                 
 Factor.

7. MAXIMUM STABLE GAIN (MSG):
                   
This is the MAXIMUM value MAG can have, which is achievable when K = 1, i.e., on the verge of
                    instability.

                   
                                                                                     
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