After scouring the web for a set of “typical” PLL specifications and not having had much luck we decided to collect and tabulate a set of typical specifications ( by no means complete, but including most of the relevant specifications). These specifications are available in the Signal Processing Group Inc.’s website under the complementary items link. Interested readers are invited to visit the website and the link.

A PLL is a difficult circuit to simulate using active and passive device models on a circuit simulator. Specially if it is a fast PLL. The signals are fast but the time constants of the filter are slow. The circuit simulator can have problems following both fast and slow signals. In addition it usually takes quite a few cycles of frequency to get a reasonable solution. (However if one is prepared to wait then the results can be very accurate at times.) A reasonable solution to  problems of simulation time and circuit simulator issues, is to use behavioral models which tend to very fast in simulation,  but not as accurate. A methodology that employs a mixture of MATLAB analysis, behavioral models and finally detailed circuit simulation is a practical one. Use MATLAB and behavioral models to get close to a solution and then fine tune using circuit simulation. Please vist the Signal Processing Group Inc.’s website for more technical information and ways to engage with us or simply ask questions or insert comments.

A low noise amplifier, a LNA, is an important circuit in many types of RF and wireless systems. It is usually the first circuit to be encountered in an amplifier chain that starts at the output of the antenna. The FRIS formula shows that in a chain of amplifiers, the gain and noise of the first amplifier sets the noise of the entire chain. These amplifiers have a number of specifications that are used in the industry. A white paper published by Signal Processing Group Inc., describes these specifications and  provides their descriptions. Familiarity with these specifications can only result in better designs. Please access this paper from the SPG website. Use the “Complementary” link .

QPSK is a popular format for digital communications. QPSK modulation has been described in this blog in earlier posts. This post describes the coherent demodulation technique for QPSK composite signals. The white paper may be found under the ” Complementary” menu item in the Signal Processing Group Inc. website.