From the trade magazines: litz wire, vector network analyzers, SDR

Another selection of amateur radio related items appearing recently in the electronic engineering trade publications.

Litz wire and other component cleverness
If you’re not familiar with it, litz wire is not named after a person or a place. It’s short for Litzendraht, the German term for braided, stranded, or woven wire. It’s a very clever solution to the problems and inefficiencies caused by the skin effect — as the frequency of the current that a wire carries increases, the current tends to go to the outside of the wire.

Vector network analyzers support versatile testing
Among the most valuable of RF/microwave test tools is the vector network analyzer (VNA), which can measure amplitude and phase with frequency. VNAs have long become associated with the measurements of complex impedance parameters—such as scattering (S) parameters—using the test data to design efficient impedance matching networks for the optimum transmission of high-frequency signals through active and passive devices and networks. At present, VNAs are available from both well-known and not-so-well-known instrument manufacturers, in both bench top and portable configurations for making measurements on high-frequency (HF) through millimeter-wave-frequency signals.

Integrated RF analog, multi-standard, software-defined radio receivers
The scaling of CMOS technologies typically has a great impact on analog design. The most severe consequence is the reduction of the voltage supply. Imec and Renesas have managed to put a complete, high-performance SDR (Software Defined Radio) receiver into a 28nm CMOS process with a 0.9V power supply. The IC has everything except a PLL on a single monolithic chip. (See Figure 1.) This is an impressive integration of analog functionality.

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