Notes

Outline

Diode Detector Simulation, Design and Measurement

1. How to use S-parameter data files in ADS

These files are used for Simulation Use this part of the tutorial to simulate the RF performance of your circuit.  You need to include the lengths of all lines (including the pads for soldering elements to).  These are found in the layout section, so you will do some back-and-forth between layout and simulation. Some elements are available in the standard libraries (the cap in this lab), others are not (the diode in this lab).  When they are not available, you will have to “create” them using user-defined S-parameters and lines (MLIN).  These can come from data sheets (like the HP website) or from measurements (like for this lab).

In the second half of the tutorial, we will do the Layout “Artwork” is used to define the size and shape of solder connects for components like capacitors, diodes, RF chips, etc. The dimensions of solder pads (where you actually connect your circuit) are specified on data sheets.  They are also available in the libra “library” for many standard elements. The size of pads add length to your lines, so you will need to include them in your simulation for most accurate results.  This means you need to figure out their size before you simulate the circuit, so you will do some back-and-forth between layout and simulation.

1-1. There are two ways to get your S-parameters: Measure them (most accurate) Find them on the web or other data sheet (we’d like this to be most accurate, but for this lab it isn’t) These methods are described below, for your reference.  Measured values are given at the end.

1-2. To measure S-parameters of the diode Build the circuit with just a length of line attached to the device. Measure the input impedance using the network analyzer. Compensate for the length of the line to find the S-parameters of your device (Matlab code to do this is included)

1-3. Find the S parameters of your HP diode, Look on this web page:http://www.hp.com/HP-COMP/rf/hprfhelp/products/diodes/hsms285x.htm#s-data

1-4. Copy and Paste the data into a text file (diode.txt).  Put this text file into your project directory.

Slide 9

1-5. Measured 2-port S-parameters of your diode including the pads: filename is diode2pt.txt

1-6. Get a Part by typing S2P in the part window & Edit Parameter

1-7. Adding Zin block, MLIN, MLOC, MTEE and S2P

1-8. Simulate your Circuit to find Zin

1-9. Edit C_pad1 Parameter: Define C, W,S,L from the data sheet.  Units are from your default. (C_pad1 represents a capacitor WITH its solder pads.)

1-10. Insert S2P parameter file

1-11. Simulate the circuit and look at the graph (Data Display)

1-12. Data Display

1-13.  The Zin Plot, Add markers at 2.4 GHz and 2.6 GHz on both the curves

1-14.  Add your single-stub network to the circuit

1-15. Data display after simulating

2. Generation of Layout You have now simulated how your circuit should work, but you can’t mill it.  The mill will not know what to do with the S2P element and won’t leave any particular solder pads for the capacitor. In this part of the tutorial, you will prepare the circuit to be soldered, but won’t be able to simulate its performance.

Use of Layout “Artwork” is used to define the size and shape of solder connects for components like capacitors, diodes, RF chips, etc. The dimensions of solder pads (where you actually connect your circuit) are specified on data sheets.  They are also available in the ADS “library” for many standard elements. The size of pads add length to your lines, so you will need to include them in your simulation for most accurate results.  This means you need to figure out their size before you simulate the circuit, so you will do some back-and-forth between layout and simulation.

2-1. Get a diode from Component Library.

2-2. Select diode from part library that is the same case size as ours

2-3. Replace the 2-port data element with the Diode and artwork

2-4. Click on the Layout and then Generate/Update Layout

2-5. Click OK on the message

2-6. Layout with the diode

Remove the Diode Remove all parts that will be soldered on (diode and capacitor) before saving the file to be milled. If you don’t, it will “mill” their outline and mess up your board.

2-7. Layout without the Diode This is what you should mill.

What to turn in Design two diode detectors, one for 2.4 GHz, and the other for 2.4 GHz.  (Slight change in single stub match.) Print out the layout of your diode detectors, with sizes clearly marked. Clearly mark where holes for shorts should go (there will be two on each detector).

Question? If you didn’t “get” something in this tutorial, please tell Dr. Furse or You Chung which slide(s) is confusing. Thank you!