UWEE572-Lab 2 Parameter Extraction Technique Solved

I. Physical device: Coupled TL
 

II. Equivalent circuit (Lumped element model)
 

III. Unknown parameters: C1G, C2G, C12, L11, L22, and L12 Assume C1G=C2G and L11=L22.

We have 4 unknowns.  C1G, C12, L11, and L12

We need 4 equations
 

The coupling coefficient KC and KL are defined as

C12

 

KC=C1G+C12

L12

KL=L11                         (L22=L11)

Use TDR to get these equations.

HW2:  Analysis of Coupled Noises on PCB             1/22/2020

Due:_2/5

Important:

Conducting this lab is optional.  You may use the premeasured data to do the analysis.  If you are not doing experiments, skip Section III.

*** Data transfer from TDS8200 to PC ***

Use the attached USB memory card (USB with CompactFlash) to transfer data.  

You can also use a floppy disk.  See below.

If you save data directly to FD, FD may not save the complete data.

To mitigate this problem, please save data on TDR (C:, Windows Desktop).  When you exit TDR app (File menu), you will see the regular Windows Desktop with your data. Transfer data to FD.  Then transfer to a PC.

*** Time information ***

The number of points and sample rate can be found in Setup.  Click Setup then check Horizontal.  The default is 4000 points.

***Display shows either voltage or reflection coefficient (rou).  Choose voltage in setup.

If TDS8200 has only two channels (Ch1 and Ch2), Ch1 will be used as the source channel (TDR ON) and Ch2 will be used as a receive channel (TDR OFF).   The RF switch box is connected to Ch2 so that two signals (Ch A and Ch B) can be monitored by selecting the lines.

If DUT has 3 or 4 ports, the unused ports must be terminated with a matched impedance (or the load condition specified in this lab).

I. Objectives
This lab is to introduce the characteristics of backward and forward coupled noises on coupled transmission lines.  You will also study how to obtain the coupling coefficients and lumped element models from the measured data.  Data must be saved on a PC so that you can process and analyze it. It is assumed that you are already familiar with TDR.

The coupled lines are fabricated on a FR4 PCB and the TL structure is microstrip TL.  As we studied in the coupled line section, the backward coupled noise is related to (KC+KL) while the forward coupled noise is related to (KC-KL). The coupled lines using the microstrip TL show the forward coupled noise because KC is not equal to KL. Whereas the stripline TL in which we have KC=KL, does not create the forward coupled noise. One of the objects of this lab is to estimate KC and KL from the time-domain response. Because KC and KL are given by equivalent capacitors and inductors of the coupled lines, we should also be able to estimate the values of these lumped elements using additional relationships.

Reference:

EE480 lecture note on coupled lines

TDS8200 users note

II. Experimental setup
Lab Equipment:

TDS8200 and Switch box

TDS8200 TDR with 80E04 (TDR head)

 

Figure 1: A TDS8200 Digital Sampling Oscilloscope. A Sampling Module

 

Figure 2: Setup

Test boards

TL PCB with different coupling characteristics Use A, B and C samples on PCB.

 Coupled Lines              |             A          |             B          |             C          |

 Coupled length     d       |            10cm     |            10cm     |            5cm       |

 Line separation     s       |            0.5mm  |            1mm     |            0.5mm  |

 

Test cables:

Cable 1: Blue

Cable 2: Blue

Cable 3: Blue

Cable 4: Short black cable for an extra delay line

Load and devices

SHORT

OPEN (No connection.   Strictly speaking this is not OPEN.) THRU

III. Experimental procedure
(1) Turn ON TDS8200 and SW box.

Make sure the Tx output of SW-box is connected to the microwave switch (gray cable). The center SMA connector of the microwave switch must be connected to Ch2 of TDS8200. SW box has two switches.  Only the left side switch (show Ch A and Ch B) is used in this lab.

 

(2) Connect cables and obtain the characteristics of the input waveforms and calibration of Ch A (cable 2) and Ch B (cable 3)
The gain responses of Ch A and Ch B may not be the same and we need to check them.

Using the THRU measurement, obtain the peak voltage and rise time of the input signal.

Connect the TDR cable (Ch1) and Ch A directly as shown below. Select Ch A using the SW box.  Save Ch A data and use MATLAB or other software to get the peak voltage and rise-time.

 

Similarly, connect the TDR cable (Ch1) and Ch B directly as shown below. Select Ch A using the SW box.  Save Ch B data and use MATLAB or other software to get the peak voltage and rise-time.

Note: The responses (rise-time, voltage level) of Ch A and Ch B may not be the same due to the microwave switch and different cables.