In the design of microwave linear amplifiers , s parameters are used extensively. It is assumed that the amplifier will be bilateral. i.e. the s parameter, s12 will be non – zero. However, if the effect of s12 on gain is relatively low, then we can accept this and assume that s12 is zero. The reverse transmission from the output to the input of the amplifier is negligible. Under this condition, the design of the amplifier can be done under a unilateral assumption. This type of design is much simpler than a full bilateral amplifier design. A way to quantify the conditions under which we can, indeed, use the unilateral assumption is to use the unilateral figure of merit U. This predicts the amount of error in the gain in dB, if the unilateral assumption is used. If the error in gain is small enough, then the designer can revert to a unilateral design. This saves time and effort. This factor is simply calculated from the s parameters of the device. A simple javascript has been written by the design team at Signal Processing Group Inc. It allows engineers to calculate U quickly. The script can be accessed from the website by visiting complementary items in the menu and selecting the calculator item in the list.

Predictions are always risky. It is not a science. However, for what it is worth, here are our predictions for 2016, a 9 year.There will be some endings for market spaces. However, there will be new beginnings in others. Cell phones may saturate. Semiconductors are poised for a rebound but await a really killer app as usual. Expect more mergers in the semi industry.New Space is opening up with a few companies targeting opportunities in Space. SpaceX, Virgin Galactic, Oneweb etc. Automotive is opening up with serious opportunities in Hybrids and EV. Medical electronics will grow significantly. The 3-D printing business will grow at a healthy rate.Online business will be strong as usual. More and more Online business. This is because of convenience and large catalogs of items. We see Amazon, AliBaba, EBAY keep going as usual. In  short there will be a lot of opportunity for those who can take advantage of them. Having said all that we expect some serious argument  from differing opinions!!! 

Baluns or balanced to unbalanced are magnetic components used to convert balanced and unbalanced signals ( from common) to provide the correct phasing for amplifiers and other electronics that operate in the differential mode. A popular connection is to use a balun to connect a single ended, unbalanced input to a balanced differential input for an amplifier. There are also UNUNs. Baluns can be implemented in discrete and integrated form. There are RF transformers that act as baluns and there are transmission line baluns. Generally the transmission line baluns are wider band.The two do not operate the same way.Some big names in this world are Guanella, Ruthroff and Sevick. Check out our balun post by going to our website and selecting the “complementary: link and selecting the post from the list. Please contact us at spg@signalpro.biz for other questions.Other interesting technical articles are also available free of charge.

If a circuit has to be interfaced to a computer, the interface that is most likely to be used is a USB interface. If it is wireless, either a wireless USB or a Bluetooth LE type interface. Among the two of these, the USB interface is simpler. We have decided to use it in some of our products for analog and wirelss applications.

It is interesting that the simplest USB interface that can be used is a fixed function Human Interface Device interface or HID. This does not require extensive effort to program drivers or other complicated software. The snag is however, that the data transfer rate is somewhat limited to about 64 KBS.

Getting information about HID devices and tutorials for the newbie is really quite difficult, and it seems that USB interfacing is a bit of a black art. We are currently building USB interfaces using HID technology for a USB to SPI bridge application.

The SPI format is used in a programmable RF amplifier for control. The other side is of course the computer. Measurement data of the gain of the amplifier is also interfaced to the USB port. Our intent is to share our experience and design information to all. Keep tuned if interested.

Please visit our website at http://www.signalpro.biz for more information about our products and services. You can also download free technical articles from the site. This is located under the “complementary” link.

Following on the post about the basics of microstrip patch antennas, this post addresses the methods of feeding the RF signal to the antenna. A number of popular methods are discussed and described. The fundmentals are quite clear. A follow on post to this one is the analysis and description of the input impedance of the microstrip patch antenna to be posted shortly. Interested readers can download the article from the Signal Processing Group Inc, website by clicking on the menu item ” complementary”, and choosing the appropriate link.

A rectangular patch antenna using PCB and microstrip technology is a very useful component to develop if a simple, small footprint, easy to use antenna is desired. As the name implies it is a rectangular structure formed on a top PCB layer with a ground plane under it. A recent set of white papers released by Signal Processing Group Inc., address this antenna design. The first of these is now accessible from the SPG website by using the “complementary” menu item. It is free for use. The rest of the white papers will be posted in subsequent posts. Interested readers may follow these as and when they are posted. Keep in touch!

Following an article published recently in the Signal Processing Group Inc., website on parabolic reflector antennas, this post deals with describing typical specifications of such an antenna. Interested readers may access the white paper from the SPG website by using the “complementary” link.

Parabolic dishes are very popular as antennas. Antenna design and manufacture is a specialized activity that takes many years to learn and execute.
However, the user must also learn the basic terms that are used in specifying and using antennas. Recently Signal Processing Group Inc., released a white paper
on the basics of such antennas. It is meant to be a tutorial study of these antennas that allows a layman’s understanding of the parameters involved. Interested
parties can access this paper from the SPG website at www.signalpro.biz.

A PLL is a very popular and useful component with many applications and forms. Its design is usually not easy to simulate on a device level and can also be very time consuming. In order to speed up the design work, the PLL can be simulated using an analog behavioral model ( ABM). ABM resources are usually available in most circuit simulators and other CAD tools. A recent paper from Signal Processing Group Inc., presents the results of an ABM simulation for a PLL. Interested readers can access the paper from the SPG website under the Complementary link.

A phase modulator is in the class of angle modulators of which FM is also a member. A lot has been written about FM but not many articles address the generation and simulation of phase modulators. Signal Processing Group Inc., recently released a simple version of the phase modulator and its behavioral simulation. The results of a PSPICE ABM simulation model are shown below. Please contact SPG at spg@signalpro.biz for details.