Project

RF, Digital Radio and Metamaterial Fundamentals

Project

Digital Non-Foster Circuits and Non-Foster Antennas

Overview

Work in assigned project groups.

The objective of this project is to simulate Project: Digital NonFoster Circuits and Non-Foster Antennas.

NOTE: Use the Project Report Template and keep answers to questions on consecutive sheets of paper with all plots at the end.

IN NO CASE may code or files be exchanged between students, and each student must answer the questions themselves and do their own plots, NO COPYING of any sort! Nevertheless, students are encouraged to collaborate in the lab session.

Part 1: Digital Non-Foster Circuit Simulation

In this part, we investigate Project: Digital NonFoster Circuits for negative capacitance
This used in Digital Non-Foster Radio Architectures for wideband matching of electrically small antennas
For details on radio design concepts, see:

Digital non-Foster circuits
Digital Non-Foster radio architecture for wideband matching of electrically small antennas

Load and run the Maathcad digital non-Foster simulation file as follows:

Download file rfDigRadMeta18zTxNonFos_a.xmcd.zip and unzip it to your preferred Maathcad directory/folder
Run Maathcad program, and open the "rfDigRadMeta18zTxNonFos_a.xmcd" design,

You MUST edit the Maathcad file to obtain the proper plot for your report
Near the bottom of the file, it computes the digital non-Foster input impedance Zin(s) as

Where

You should see these formulas near the bottom of the rfDigRadMeta18zTxNonFos_a.xmcd Maathcad file

See the following paper containing the theory and needed parameters:

Patrick J. Kehoe, Killian K. Steer, and Thomas P. Weldon, "Stability Analysis and Measurement of RC and RL Digital Non-Foster Circuits with Latency," IEEE SoutheastCon 2017 Proceedings, Charlotte, NC, Mar. 31 - Apr. 2, 2017.

Near the bottom of the file, you will see the plot that must be added to your report

It has errors, and will look similatr to this:

Fig 001

Edit the parameters (blue circle above) so that the plot (magenta circle above) is almost identical the Fig. 6 of the paper cited above

Save a snapshot for your report

How closely does the imaginary part of Zin(s) match the ideal reactance of a negative capacitor?

At what frequency does the imaginary part of Zin(s) begin to diverge from the ideal reactance of a negative capacitor?

What is the sample rate of the system?

As an optional exercise, reduce latency to 1 ns, and observe the changes

What clock determines the carrier frequency?

Save your work!

Part 2: Non-Foster Antenna Bandwidth Improvement

From a PC terminal, you must first open a remote Linux session, then proceed as for a Linux terminal
After ADS starts you should get a starting window similar to this (navigate into your apps/ads folder):
Load and run the pulse example as follows:
Download the 7zap archive as follows:

Download the 7zap archive rfDigRad_NonFosAnt_30jul2018a_wrk.7zads to your ads directory
Use MenuBar::File::Unarchive to extract the project into your ADS directory as follows

You should find a new directory rrfDigRad_NonFosAnt_30jul2018a_wrk created in apps/ads
Run ADS and open the new RFcourse2012_pulse1a_wrk workbook by double-clicking it

Go down through the directory tree to pulse1/schematic and double click that schematic file

and the following schematic should appear.

The circuit in the cyan circle below takes s-parameters of the antenna (Zant, S33)
The circuit in the yellow circle below takes s-parameters of the passively-matched (inductor-matched) antenna (ZindMatch, S22)
The circuit in the blue circle below takes s-parameters of the non-Foster (-40pF) matched antenna (ZnonFos, S11)

Fig 002

Double-click the transmission antenna (blue arrow above) and look at the variables in the pop-up menu.
Use the mouse to select the variables and observe the changing description at the bottom of the pop-up.
Double-click the "gear" icon (yellow arrow above) in the upper right of the window to simulate.
After simulation the plotted results should pop up in a new window
One plot is the s-parameters similar to below

FIg 003

The dip in S22 (blue arrow above) it the center frequency of the passive match at 20 MHz
Adjust your non-Foster capacitor (-40 pF originally) so that the dip in S12 (red arrow above) is also at 20 MHz

Then, slide markers m1 and m2 to measure the bandwidth at the -6 dB points
Save this new plot for your report
Record the 2 frequencies and bandwidth for your report
Record the new value for your non-Foster capacitance (changed from the original -40 pf)
Then, slide markers m3 and m4 to measure the passive-matched antenna bandwidth at the -6 dB points
Record the 2 frequencies and bandwidth for your report

Rerun the simulation one last time to make sure that your plot is for the final value of the capacitor

The second plot is the impedance, similar to below

Fig 004

Use your adjusted new value from above for your non-Foster capacitor (-40 pF originally)

Save this new plot for your report
Then, slide marker m5 to 20MHz to measure the real part of the antenna Zant at the tuned frequency
Then, slide marker m7 to 20MHz to measure the imaginary part of the non-Foster matched antenna ZnonFos at the tuned frequency (it should be near zero ohms!)
Record the measured values for your report

Save your work!

See report template below

Report Data

============================ WARNING !! ====================================
**** WARNING **** YOU MUST USE THE PROJECT REPORT TEMPLATE Below:

See the Project Report Template at bottom of this page
A well-written report/paper is EXPECTED
STRONGLY RECOMMEND that you read IEEE authorship series: How to Write for Technical Periodicals & Conferences
Clearly describe everything, including:

variables in block diagrams
variables in formulas
units of variables kHz, pF, nH, m, s,
all traces on plots
all curves on plots
all results in any tables

Minimum required data content for your report and demos

Required theory/formulas numbered as below:

(1) formula for Zin(s) as shown above
(2) formula for Hrc(z) as shown above

Required figures:

Any illegible plots receive zero credit (must be able to read all numbers, axes, labels, curves, grids, titles, legends)
All plots must of professional quality as in IEEE papers

LEGIBLE block diagram of the Thevenin digital non-Foster circuit that you simulated (see the circuit in the paper)
LEGIBLE simulation showing Zin(s) as in Fig 001 above (magenta circle), with appropriate caption
LEGIBLE schematic showing the non-Foster antenna match circuit as in Fig 002 (blue circle only)
LEGIBLE simulation showing s-parameters including your final non-Foster match as in Fig 003
LEGIBLEsimulation showing impedances including your final non-Foster match as in Fig 004

Required tabular data content:

Table of Maathcad results with 4 columns: frequency in kHz, Maathcad imaginary part of Zin(s), and ideal reactance, and percent error from ideal

Row 1: imaginary part of Zin(s), and ideal reactance at 50 kHz
Row 2: imaginary part of Zin(s), and ideal reactance at 100 kHz
Row 3: imaginary part of Zin(s), and ideal reactance at 150 kHz

Table of ADS results with 2 columns: parameter and parameter value

Row 1: the final value of your non-Foster capacitance (change to the -40 pf) in pF
Row 2: the final bandwidth of your non-Foster match in MHz
Row 3: the bandwidth of the passive match in MHz
Row 4: the real part of the antenna Zant at 20 MHz
Row 4: the imaginary part of your non-Foster matched antenna ZnonFos at 20 MHz

See report template below

NOTE ReportTemplate: Use the Project Report Template

YOU MUST ADD CAPTIONS AND FIGURE NUMBERS TO ALL FIGURES!!

ANSYS, and HFSS are registered trademarks of ANSYS, Inc. Cadence, Spectre and Virtuoso are registered trademarks of Cadence Design Systems, Inc., 2655 Seely Avenue, San Jose, CA 95134. Keysight is a registered trademarks of Keysight Technologies, Inc. MATLAB and Simulink are registered trademarks of The MathWorks, Inc. MATHCAD is a trademark of PTC INC.