I guess I'll say it again - the task of RF design is NOT a trivial undertaking. Many a *new* engineer has learned the hard way to take the sage advice of 'the old timer' in regards to hard-learned lessons and 'tricks of the trade. For the novice who needs results NOW (in a prototype, proof of concept or class project) there is no substitute for the off-the-shelf time-tested product such as those offered by minicircuits (an others). IF you're going to build millions of units and the units are going to be built in (formerly Red) China using low-cost labor then the discrete design route makes economic sense - but then you'll need vector network analyzers, spectrum analyzers and extensive design expereince down to the component level. Minicircuits simply solves most of that - and won't require you to learn the intricacies of biasing over temperture and assuring a known level of stability in any amp particular one employs in circuits they ahve designed. I dare say that there isn't: A) an RF power (output) level coupled with any B) particular frequency band C) at state of the art effeciencies that I can't find suitable parts and app notes for in minutes. Applying these designs for one's own purposes using these parts won't require the 'need to know' such specific (and irrelevant in the RF world) paramerters like device Ton and Toff times. (Although, in the design of these transistors themselves by the foundry, these parms are considered by the solid state physics majors who oversee the fabrication of such parts as 'product engineers'.) As other posters have pointed out - it's input and output Z in the form of S parameters (for direct use in uWave modelling pgms) or "Smith Charts" that are of much greater importance for the purpose of design LC (Inductor/Capacitor) Z (impedance) matching circuits. Other important parameters (for real power amps) are such as things as maximum allowable output mismatch - this clues one in as to where possible device destruction due to a mismatched load may ocurr. With the widespread proliferation of wireless 2-way as we have seen today there exists a pleathora of integrated, concisely packaged, nearly foolproof multifunction modules, ICs and packaged amps, receivers, and transceivers that can be employed for nearly every purpose under the sun. It used to be that op-amps were discrete tube and transistor designs too - and those days have been long gone for quite awhile now (Yogi Bera quote used without permission) save for perhaps one or two EE lab courses in ... But wait! Dicrete tube and transistor design is not dead! Witness the new amps from guitar amp makers like Fender and others ... what comes around goes around - but I don't think that discrete RF amp design is really going to erupt as fad anytime soon. Jim ----- Original Message ----- From: "Scott Stephens" To: Sent: Tuesday, July 10, 2001 8:45 PM Subject: Re: [EE]: Class C amps From: Jim >I recommend viewing/getting ahold of some of the old >Motorola "RF Device Data" books for a good feel on >how the RF guys spec devices. Good luck finding them. They have many good app notes, but you can find many good app notes from the many excellent online and user-freindly web sites from Siemens, Phillips, Harris, Zetex, et. And RF design & smith charting software too. Checkout http://www.rfglobalnet.com for software, tutorials, app-notes and website indexes. The last time I tried to get an app note from Motorola (several years ago), I had to have it faxed to me and it took 1/2 hour! I have found them unfreindly in several ways, which I'll refrain from detailing as they have been ranted about in this forum in the past, especially regarding getting their parts. It was said they are made from pure 'unobtainium'. Maybe they have to see if you are 'in the club' before they can sell to you? I don't know. >Another choice for some apps requiring RF amps/oscillators >are the family of products by www.minicircuits.com Their MMIC's or VNA's have constant 50 ohms in and out over their bandwidth, so its a no-brainer, but for the layout. And those suckers run hot and are inefficient. No substitute for good design, but cheap'n dirty. Scott **************************************************************** Freedom is pursuing your carrot, not running from a stick. The mob only rules what its members are allowed to achieve. Physics - the manifold ways the odds always get even... **************************************************************** -- http://www.piclist.com hint: To leave the PICList mailto:piclist-unsubscribe-request@mitvma.mit.edu -- http://www.piclist.com hint: To leave the PICList mailto:piclist-unsubscribe-request@mitvma.mit.edu