RF Circuit Design, 2nd Edition

Chapter 1

Difference between RF and Digital Circuit Design

1.1 Controversy

For many years, there has been continued controversy between digital and RF circuit designers, some of which are given below:

• RF circuit designers emphasize impedance matching, whereas digital circuit designers are indifferent to it.
• RF circuit designers are concerned with frequency response, whereas digital circuit designers are interested in the waveform, or “eye's diagram.” In other words, RF circuit designers prefer to work in the frequency domain, whereas digital circuit designers like to work in the time domain.
• As a consequence of the above, in a discussion of the budget for equipment, RF circuit designers like to purchase good network analyzers, whereas digital circuit designers prefer to buy the best oscilloscopes.
• RF circuit designers use the unit of dB_W, whereas digital circuit designers insist on using dB_V.
• Not only are the design methodologies different, so are their respective jargons. Digital circuit designers talk about AC bypass capacitors or DC blocking capacitors, but RF circuit designers rename those as “zero” capacitors.

It almost seems as if they were two different kinds of aliens from different planets. Even in some conferences or publications, these two kinds of “aliens” argue with each other. Each tries to prove that their design methodology is superior to the others'. Eventually, nobody is the winner.

Let us outline the main controversies in the following.

1.1.1 Impedance Matching ...