Return-Path: X-Spam-DCC: paranoid 1233; Body=2 Fuz1=2 Fuz2=2 X-Spam-Checker-Version: SpamAssassin 3.1.3 (2006-06-01) on lipkowski.org X-Spam-Level: X-Spam-Status: No, score=0.1 required=5.0 tests=BAYES_00,DNS_FROM_AHBL_RHSBL, FORGED_RCVD_HELO,HTML_MESSAGE,HTML_TINY_FONT autolearn=no version=3.1.3 Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by paranoid.lipkowski.org (8.13.7/8.13.7) with ESMTP id u1MIwd9c006349 for ; Mon, 22 Feb 2016 19:58:39 +0100 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1aXvdb-00069b-3N for rs_out_1@blacksheep.org; Mon, 22 Feb 2016 18:55:15 +0000 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1aXvda-00069S-Kp for rsgb_lf_group@blacksheep.org; Mon, 22 Feb 2016 18:55:14 +0000 Received: from rhcavuit02.kulnet.kuleuven.be ([134.58.240.130] helo=cavuit02.kulnet.kuleuven.be) by relay1.thorcom.net with esmtps (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.86) (envelope-from ) id 1aXvcW-0007YU-JD for rsgb_lf_group@blacksheep.org; Mon, 22 Feb 2016 18:55:13 +0000 X-KULeuven-Envelope-From: rik.strobbe@fys.kuleuven.be X-KULeuven-Scanned: Found to be clean X-KULeuven-ID: B1DD912834F.A936A X-KULeuven-Information: Katholieke Universiteit Leuven Received: from icts-p-smtps-1.cc.kuleuven.be (icts-p-smtps-1e.kulnet.kuleuven.be [134.58.240.33]) by cavuit02.kulnet.kuleuven.be (Postfix) with ESMTP id B1DD912834F; Mon, 22 Feb 2016 19:53:42 +0100 (CET) Received: from ICTS-S-HUB3.luna.kuleuven.be (icts-s-hub3.luna.kuleuven.be [10.112.9.17]) (using TLSv1 with cipher AES128-SHA (128/128 bits)) (No client certificate requested) by icts-p-smtps-1.cc.kuleuven.be (Postfix) with ESMTPS id AF73B403B; Mon, 22 Feb 2016 19:53:39 +0100 (CET) Received: from ICTS-S-MBX1.luna.kuleuven.be ([fe80::edaf:341f:90e:f70e]) by ICTS-S-HUB3.luna.kuleuven.be ([fe80::a470:76b3:406d:2b1a%27]) with mapi id 14.03.0224.002; Mon, 22 Feb 2016 19:53:39 +0100 X-Kuleuven: This mail passed the K.U.Leuven mailcluster From: Rik Strobbe To: "rsgb_lf_group@yahoogroups.co.uk" CC: "rsgb_lf_group@blacksheep.org" Thread-Topic: [rsgb_lf_group] Single Stage Class-B Thread-Index: AQHRbZbhSpyl6tSxiUeZHKOUfT9bG584Y18G///xfQCAABEeQQ== Date: Mon, 22 Feb 2016 18:53:38 +0000 Message-ID: <7E7DFBB4D102A04DB5ADC88D66628A4A444D7A6C@ICTS-S-MBX1.luna.kuleuven.be> References: <7E7DFBB4D102A04DB5ADC88D66628A4A444D7A4A@ICTS-S-MBX1.luna.kuleuven.be>, In-Reply-To: Accept-Language: nl-BE, en-GB, en-US Content-Language: nl-BE X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [10.112.11.14] MIME-Version: 1.0 X-HELO-Warning: Remote host 134.58.240.130 (rhcavuit02.kulnet.kuleuven.be) used invalid HELO/EHLO cavuit02.kulnet.kuleuven.be - verification failed X-Scan-Signature: af5cbdb1bd8719c0c42cc590345d3147 Subject: LF: RE: [rsgb_lf_group] Single Stage Class-B Content-Type: multipart/alternative; boundary="_000_7E7DFBB4D102A04DB5ADC88D66628A4A444D7A6CICTSSMBX1lunaku_" X-SA-Exim-Scanned: Yes Sender: owner-rsgb_lf_group@blacksheep.org Precedence: bulk Reply-To: rsgb_lf_group@blacksheep.org X-Listname: rsgb_lf_group X-SA-Exim-Rcpt-To: rs_out_1@blacksheep.org X-SA-Exim-Scanned: No; SAEximRunCond expanded to false X-Scanned-By: MIMEDefang 2.56 on 10.1.3.10 Status: O X-Status: X-Keywords: X-UID: 6943 --_000_7E7DFBB4D102A04DB5ADC88D66628A4A444D7A6CICTSSMBX1lunaku_ Content-Type: text/plain; charset="Windows-1252" Content-Transfer-Encoding: quoted-printable A single stage class B amplifies the signal over 180 degrees (ie. half the = sine). As long as the amplifier is not saturated the amplitude at the output is al= most linear proportional to the input amplitude, but the signal is distorte= d due to the fact that half of the sine is missing. In a class B push-pull each FET (or bipolar transistor, tube) will amplify = the "opposite" 180 degrees of the input signal and these will combine at th= e output , so apart from the cross-over distortion the output signal in pre= tty undistorted. 73, Rik ON7YD - OR7T ________________________________ Van: rsgb_lf_group@yahoogroups.co.uk [rsgb_lf_group@yahoogroups.co.uk] Verzonden: maandag 22 februari 2016 19:39 Aan: rsgb_lf_group@yahoogroups.co.uk CC: rsgb_lf_group@blacksheep.org Onderwerp: Re: [rsgb_lf_group] Single Stage Class-B There's nothing inherently "more linear" about push pull over a single stag= e, given you run the same device at the same power per stage (ie half the P= P level) 'jnt On 22 February 2016 at 18:34, Rik Strobbe rik.strobbe@fys.kuleuven.be [rsgb_lf_group] > wrote: Hello Andy, the advantage of a push-pull class B amplifier is that it it pretty linear = at higher power levels. 73, Rik ON7YD - OR7T ________________________________ Van: rsgb_lf_group@yahoogroups.co.uk [rsgb_lf_group@yahoogroups.co.uk] Verzonden: maandag 22 februari 2016 18:31 Aan: rsgb_lf_group@blacksheep.org; rsg= b_lf_group@yahoogroups.co.uk Onderwerp: [rsgb_lf_group] Single Stage Class-B Whilst out walking and pondering, as one does.... There are hundreds of designs out there for linear power amps using FETS. = They all use a similar design, push-pull with centre tapped ferrite cored = transformers at input and output, often with resistive feedback - and all b= roadband. The design is so standard it's become tedious ... and as I don'= t do tedious, it made me think: Back in days of yore when those big bottles ruled the roost , apart from a= few designs for UHF, they were all single ended. So, why not a single ended MOSFET amp (for single band operation)? We're = used to seeing single device for class-E, where the tank circuit does much= of the waveform cleaning, and reduces the low pass filter requirements. = So what's wrong with a tank-based design for class-B? A single ended amp can even be made ferrite free (although a final stage DC= feed choke would no doubt benefit from it). Apart from a few very low po= wer designs, I don't recall seeing any designs for single band ferrite free= linear amps using power MOSFETS. Only major downsides I visualise is that load resistance at the device is 4= times lower for the same Vdd and Pout , and device dissipation is doubled Has no one ever bothered, because broadband transformer push-pull is so str= aightforward? Has a trick been missed? Andy G4JNT __._,_.___ ________________________________ Posted by: Andy Talbot ________________________________ Reply via web post =95 Repl= y to sender =95 Reply to group =95 Start a new topic =95 Messages in this topic (3) Visit Your Group [Yahoo! Groups] =95 Privacy = =95 Unsubscribe =95 Terms of Use . __,_._,___ --_000_7E7DFBB4D102A04DB5ADC88D66628A4A444D7A6CICTSSMBX1lunaku_ Content-Type: text/html; charset="Windows-1252" Content-Transfer-Encoding: quoted-printable

A single stage class B amplifies the signal over 180 degrees (ie. half t= he sine).

As long as the amplifier is not saturated the amplitude at the output is= almost linear proportional to the input amplitude, but the signal is disto= rted due to the fact that half of the sine is missing.

In a class B push-pull each FET (or bipolar transistor, tube) will ampli= fy the "opposite" 180 degrees of the input signal and these will = combine at the output , so apart from the cross-over distortion the ou= tput signal in pretty undistorted.

 

73, Rik  ON7YD - OR7T

 

Van: rsgb_lf_group@yahoogroups.co.uk [rsgb= _lf_group@yahoogroups.co.uk]
Verzonden: maandag 22 februari 2016 19:39
Aan: rsgb_lf_group@yahoogroups.co.uk
CC: rsgb_lf_group@blacksheep.org
Onderwerp: Re: [rsgb_lf_group] Single Stage Class-B

 

There's nothing inherently "more linear" about push pull ove= r a single stage, given you run the same device at the same power per stage= (ie half the PP level)    

'jnt


On 22 February 2016 at 18:34, Rik Strobbe rik.strobbe@fys.kuleuven.be [rsgb_lf_group] <rsgb_lf_gro= up@yahoogroups.co.uk> wrote:
=
 

Hello Andy,

 

the advantage of a push-pull class B amplifier is that it it pretty line= ar at higher power levels.

 

73, Rik  ON7YD - OR7T

 

Van: rsgb_l= f_group@yahoogroups.co.uk [rsgb_lf_group@yahoogroups.co.uk]
Verzonden: maandag 22 februari 2016 18:31
Aan: rsgb_lf_group@blacksheep.org; rsgb_l= f_group@yahoogroups.co.uk
Onderwerp: [rsgb_lf_group] Single Stage Class-B

 

Whilst out walking and pondering, as one does....

There are hundreds of designs out there for  linear power am= ps using FETS.  They all use a similar design, push-pull wit= h centre tapped ferrite cored transformers at input and output, often with = resistive feedback - and all broadband.   The design is so standard it's become tedious ... and as I don't do tedious, it m= ade me think:

Back in days of yore when those big bottles ruled the roost ,  ap= art from a few designs for UHF, they were all single ended.

So, why not a single ended MOSFET amp (for single band operation)?&nbs= p;  We're used to seeing single device  for class-= E, where the tank circuit does much of the waveform cleaning, and reduces t= he low pass filter requirements.    So what's wrong wit= h a tank-based  design for class-B?

A single ended amp can even be made ferrite free (although a= final stage DC feed choke would no doubt benefit from it).  = ; Apart from a few very low power designs, I don't recall seeing any design= s for single band ferrite free linear amps using power MOSFETS. 
Only major downsides I visualise is that load resistanc= e at the device is 4 times lower for the same Vdd and Pout , and device dis= sipation is doubled

Has no one ever bothered, because broadband transformer push-pull is s= o straightforward?
Has a trick been missed?  

Andy  G4JNT



__._,_.___
Posted by: Andy Talbot <andy.g4jnt@gmail.com>
Reply via web post =95 Reply to sender =95 Reply to group =95 Start a new topic =95 Messages in this topic (3)

.

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