1. IMNLab Calibration Guideline
This document helps the user to obtain calibration data files for IMNLab optimization correctly through one example based on a real circuit.
Download calibration guideline here: imnlab_calibration.pdf
Download calibration example here: imnlab_calibration_example.pdf
Obtaining correct calibration data is critical for later impedance match network design. It is highly recommended that the user takes some time to go through the above documents in details.
Four sample files have been included in the installer package. The user may skip the calibration step and just experience the software immediately after installation.
Some tips for obtaining more precise calibration data
Recently the author has successfully designed an impedance matching network working from DC to 12 GHz by using IMNLab. It is rather easy to get good calibration precision for frequency lower than3 GHz. But for frequency above 3 GHz, more cares must be taken. As stated in the calibration guidelines, IMNLab assumes ideal calibration standards “OPEN”, “SHORT” and “MATCH”. So how “ideal” the calibration standards are will greatly affect the calibration results. Below are some tips to obtain good standards:
“OPEN”: This standard is naturally ideal. The user just needs to disconnect the chain at the calibration point. The fringe effects will be counted into the path s-parameter;
“SHORT”: The main parasitic effect of this standard is series inductance. Several short wires may be soldered to GND to reduce the parasitic inductance in series;
“MATCH”: It is much more difficult to make an ideal “MATCH” standard. Based on the author’s experience, ordinary EIA-0402 1% resistors (50 or 75 OHM, depending on the system impedance) are good enough as “MATCH” standard up to 3 GHz. For frequency higher than 3 GHz, RF resistors are highly recommended to function as “MATCH” standard. Refer to this article from Vishay about RF resistors. The author may don’t have the right to post the full article here. RF resistors have flip chip terminals, thus the parasitic capacitance/inductance is much smaller than normal resistors with wrap around terminals. Also it is stated in the article that 0201 case size is superior to 0402 case size.
2. IMNLab Tutorial
This Tutorial guides the user to go through the design procedure of a wideband impedance matching network for a real circuit by using IMNLab.
Download the tutorial here: imnlab_tutorial.pdf
IMNLab 