Which CMOS Transistor is suitable for Power amplification (ranging form 7MHz ~ 9MHz) ?

Dear all,

Hope everybody is fine. I am interested to design a class E power amplifier for RFID applications (frequency ranging from 7MHz to 9MHz). For the said purpose i had designed class E PA by using MOSFET but now i am interested to replace MOSFET with CMOS Transistor. But unfortunately i am unable to decide which part number's transistor is suitable for the said requirement.

Kindly anyone suggest me any CMOS transistor (part number) which can work for the required frequency range and class E amplification.

I shall be highly grateful to you for this anticipation.

looking forward for your kind and prompt reply.

Regards

nomi114 said:

Dear all,

Hope everybody is fine. I am interested to design a class E power amplifier for RFID applications (frequency ranging from 7MHz to 9MHz). For the said purpose i had designed class E PA by using MOSFET but now i am interested to replace MOSFET with CMOS Transistor. But unfortunately i am unable to decide which part number's transistor is suitable for the said requirement.

Kindly anyone suggest me any CMOS transistor (part number) which can work for the required frequency range and class E amplification.

I shall be highly grateful to you for this anticipation.

looking forward for your kind and prompt reply.

Regards

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We can't answer that without knowing what power of a broadcast station you are hoping to build?

nomi114 said:

i am interested to replace MOSFET with CMOS Transistor

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What is a "CMOS transistor"? The 'C' in CMOS stands for 'complementary', i.e refers to the integration of a P-channel MOSFET and an N-channel MOSFET.
7MHz-9MHz is in the short-wave radio band. Do you have a licence to transmit in that frequency range? Power transmissions in that band will be readily detectable by the authorities.

alec_t said:

7MHz-9MHz is in the short-wave radio band. Do you have a licence to transmit in that frequency range? Power transmissions in that band will be readily detectable by the authorities.

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I don't know where you live but, in the US, either you have a Technician Class License or you don't. There are no special licenses for specific amateur frequencies. The 7.0 to 7.2MHz band is open for use after a simple written test with substantial broadcast power. What are the rules in your neighborhood that make you so concerned about keeping the OP from paying fines?

gophert said:

What are the rules in your neighborhood that make you so concerned about keeping the OP from paying fines?

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The site Rules, to which you agreed, namely :-
"You agree to not use the Service to submit or link to any Content which is defamatory, abusive, hateful, threatening, spam or spam-like, likely to offend, contains adult or objectionable content, contains personal information of others, risks copyright infringement, encourages unlawful activity, or otherwise violates any laws."

alec_t said:

The site Rules, to which you agreed, namely :-
"You agree to not use the Service to submit or link to any Content which is defamatory, abusive, hateful, threatening, spam or spam-like, likely to offend, contains adult or objectionable content, contains personal information of others, risks copyright infringement, encourages unlawful activity, or otherwise violates any laws."

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So, your definition requires anyone requesting advice must be asked if they have a license before giving advice?

So you must think Google Maps is "encouraging unlawful activity" if the user asked for "driving directions" and it does not ask the user whether they have a drivers license before giving driving directions. Don't be idiotic.

PS- if he says I want to build a high-voltage device to shock my neighbor, or I want to build a cell phone jammer, or even, I want to build something that emits a 10,000W signal at an FM broadcast frequency - those I could understand you getting concerned. This OP is asking about a frequency range that has amateur allocations.

Near enough everyone is aware of general safety and such as driving licences & laws relating to harming other people.

A lot of people are, completely innocently, unaware of radio licencing and transmission regulations, as so much licence-exempt radio equipment is freely available to buy and use.

Ensuring that anyone enquiring about radio transmitters is aware of the regulations, when the results of a project could cause legal issues, is just common sense.

And depending on the country, an RFID application may not be legal even with an Amateur licence that covers the frequency in use.
(I doubt it is legal on HF under an Amateur licence anywhere in the world & suspect possibly not on any band).

From a quick check, no "automated transmissions" of any type are allowed below the 10m band (~28MHz) with any Amateur licence type.
When they are allowed, there are generally very strict conditions on how they are triggered and what data they must contain.

Dear Respected @ rjenkinsgb @ gophert @ alec_t,

Thank you very much for your kind concern and reply. Here i would like to inform you that it's my study project (and there is an unlicensed band 7.7MHzz ~ 8.7Mhz for commercial applications, also they have licence for communication if required, i Think it's okay, no worries please) here i am confused only for selection of CMOS transistor (Complimentary MOS FETs P-channel & N-channel). I am interested to design a Class -E Power amplifier of output power 15W ~20W(frequency rang 7.7Mhz ~8.7MHz). please suggest me any suitable CMOS model (part number).

I shall be highly grateful to you for this act of kindness. Anxiously waiting for your kind and prompt reply..

Regards

Here are some examples of devices integrating 1 p-channel and 1 n-channel mosfet and able to pass a current of 1A (an arbitrary limit I chose) or more.

OK on the frequencies in use.

From what I can see, for your project to be "Class F" it must be based on a single switching device with an inductor as the load?

eg. See page five of the article here:
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When push-pull output is needed at RF, it's usually done with paired N type / NPN devices and a balanced transformer.
At low power levels such as a few watts, a single device is quite often adequate.

These are a couple of typical designs - around 5W and around 50W:

Interestingly, that second one is using IRF530 MOSFETS for up to 30MHz...

Purpose-made P channel RF power FETs are extremely rare compared to N channel.

You ideally need a device with switching times in the low nanoseconds range to get worthwhile efficiency at 7 - 8 MHz, it's only around 120nS per cycle.

The IRF530 used above has switching times of around 25 - 35nS so seems rather slow even for a linear amp

The IRF510 & 9510 could marginally be suitable, if you can drive the gates with enough current to rapidly charge and discharge the gate capacitance and achieve really fast switching? They are rather faster than the 530.

They are rated for 100V 4A so could be suitable in an appropriate circuit?

**broken link removed**

rjenkinsgb said:

Interestingly, that second one is using IRF530 MOSFETS for up to 30MHz...

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that design would really benefit from the GaNFET technology. Lower threshold voltage, lower gate charge and lower on resistance.

Unfortunately, they are only available in tiny 0.8mm x 0.8mm SMD packages.

They certainly look interesting in terms of gate capacitance - but either I'm missing something obvious or there is not a single parameter in there relating to switching times or operating frequencies?

rjenkinsgb said:

They certainly look interesting in terms of gate capacitance - but either I'm missing something obvious or there is not a single parameter in there relating to switching times or operating frequencies?

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You're right, it's not on the datasheet. You can expect under 2nSec rise time and fall time if I remember correctly.

I'll look to see what I have. EPC gave me a dev board and some supplemental info about 7 or 8 years ago - they needed some specific raw materials back when I was in the specialty chemicals industry. I think the founder of EPC was the son of the founder of International Rectifier.

Dear all,

Thank you very much for your kind help cooperation. Specially thanks to @rjenkinsgb your information is very fruitful. i got the idea related to my work, Thank you very much. I will contact you again if i feel any problem.

Thanks

nomi114 said:

RFID applications (frequency ranging from 7MHz to 9MHz

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there are no allocations in that part of the spectrum for RFID, so making an RFID device that works in that range would be illegal anywhere on the planet. look up the ITU regulations for ISM (industrial, scientific, and medical) bands where many unlicensed devices are allowed to operate (with some limitations, go outside the limitations, and that's illegal as well). look up your own country's regulations for ISM device as they may vary somewhat from the ITU guidelines.