PA design for 28 MHz to 1.3 GHz ? - Page 1
Forum section: electronics / rf-microwave

author: radeohedca
author_rank: Contributor
timestamp: September 12, 2019, 01:31:48 pm
content: Looking for suggestions on a 40W PA design that will cover 28 MHz to 1.3 GHz with 0dBm input. It needs to be linear, flat to within 2 dB and operate at 12 or 28v. The smaller the better. Ideally using all 50 ohm in/out MMICs (am I asking for too much ?) but will consider designs using unmatched devices.Thanks.

author: OwO
author_rank: Super Contributor
timestamp: September 13, 2019, 02:05:58 am
content: That's pretty impossible with a civilian level budget. A LDMOS amplifier can maybe cover LF to 400MHz with a wideband impedance match, but above that the output capacitance becomes significant and so the output impedance varies with frequency. GaAs devices can do it but since a PA with these kinds of specs are only used by the military consider it unobtainium.

author: radioactive
author_rank: Regular Contributor
timestamp: September 13, 2019, 02:11:50 am
content: QuoteI'm pretty sure a post like that might put you on quite a few lists. What could you possibly want to do with that kind of amplifier that doesn't involve jamming?

author: OwO
author_rank: Super Contributor
timestamp: September 13, 2019, 03:05:37 am
content: Narrowband is much easier. You can get refurbished LDMOS transistors covering 900/1300/1800/2300 MHz and get typically 50-100MHz bandwidth with the reference design. If this is for a jammer or any communications purposes you do not need wideband capability.

author: EEEnthusiast
author_rank: Frequent Contributor
timestamp: September 13, 2019, 04:49:24 am
content: You did not specify the noise figure requirement of the PA. With degraded NF, a PA can be designed to meet that span and output power.

author: radeohedca
author_rank: Contributor
timestamp: September 13, 2019, 10:48:56 am
content: Quote from: radioactive on September 13, 2019, 02:11:50 amA driver amplifier to use with an SDR that can drive PAs that I have on the various ham bands within. Primarily 6m to 23cm but 10m would be nice too.It's a power amplifier, NF is not so critical (within reason). Let's say 10 or 12dB.

author: OwO
author_rank: Super Contributor
timestamp: September 13, 2019, 01:15:14 pm
content: In that case what you need is several amplifiers, one for each band. A mrf184/mrf9060 based HF/VHF amplifier can handle 1-150MHz. For 23cm people have had success using the mrfe6s9160. For 13cm there is the AFT23S160.

author: OwO
author_rank: Super Contributor
timestamp: September 13, 2019, 01:17:12 pm
content: Here is an article about the usage of cellular band transistors for 23cm:

author: radeohedca
author_rank: Contributor
timestamp: September 13, 2019, 04:42:54 pm
content: Quote from: OwO on September 13, 2019, 01:15:14 pmI know it can be done with separate amps. The whole point of my post is to reduce the complexity of multiple amps and switching... have it all in one amplifier to use with a single SDR radio or multiband transverter. I realize it's not a simple request but the technology is getting there with Gan devices. I was just wondering if anyone on the list has done anything like this. DEMI is headed down this path according to their "Future Products" currently under development, starting with a wideband 1w amp.

author: DimitriP
author_rank: Super Contributor
timestamp: September 13, 2019, 05:19:40 pm
content: If you want one tommorow, get a ZHL-10W-202-S+Even if you use a "single amplifier" you will still l need to "switch" in matching networks and filters. By using a "single amp" you are not really reducing "complexity".

author: scatha
author_rank: Regular Contributor
timestamp: September 14, 2019, 12:42:27 am
content: OP, I assume you know this but I'll say it anyway: one thing to watch for with this approach is that most SDRs have eye-twitchingly bad harmonics and spurs on transmit, so if you're feeding a wideband PA you absolutely need bandpass filtering on the output. This will also give you some assurance that if the SDR is misconfigured or bugs out it doesn't cause chaos.

author: Bud
author_rank: Super Contributor
timestamp: September 14, 2019, 02:38:52 am
content: I second the opinion that matching will limit you in simplicity.

author: Marco
author_rank: Super Contributor
timestamp: September 14, 2019, 10:03:57 am
content: http://www.amcomusa.com/documents/publications/Sept2008a.pdfAnd 4 of those ZHL-10W-202-S+. Or if it's pulsed :https://nl.mouser.com/ProductDetail/MACOM/NPA1007?qs=sGAEpiMZZMsHFhLSzabyWRK0M1Fimleyesxji9%2FZzOsuqY2WhN%2Fbzg%3D%3DProbably not going to meet the flatness, more because of the MMIC than the combiner, but might get close.