RF design in the 21st century: Page 4 of 7

August 04, 2016 //By Paul Dillien
My first job on leaving college was maintaining military radios. I had covered RF theory, but found that the practice was significantly different. The company’s detailed design work was performed at a remote location, and shrouded in mystery. RF design was a “black art” that only a few specialists could understand. I later moved into pure logic design, where the relative simplicity of 1s and 0s held fewer uncertainties. This ultimately led me into two decades of involvement with FPGAs.

Moreover, designers can choose from a number of boards (some including FPGAs) to rapidly start product development. FPRF suppliers provide free printed circuit board layouts (Gerber files) to remove the issue of the tricky RF section and reduce risk and speed up the time to market.

Designers do not need a formal evaluation of the FPRF devices, as they can program the chips on the bench and check out the performance. Potential issues such as component matching, voltage and temperature sensitivities and cross-talk have been resolved during the chip design and qualification, relieving the user of these concerns.

Programming of the FPRF is by loading simple address and parameter details into the device over an SPI connection. This scheme allows the design to be modified in seconds. The revised performance can be tested, enabling the effects of frequency, filter bandwidth and gain to be rapidly explored (see Figures 3 and 4).


Figure 3: An example of the programmable receive path filter responses (courtesy Lime Microsystems).


Figure 4: The filter response in the transmitter path has a range of bandwidths that can be selected (courtesy Lime Microsystems).

Design category: