#qi-hardware IRC log for Tuesday, 2017-06-27

--- Tue Jun 27 201700:00
promachFor http://i.imgur.com/P99rpYA.png, I suppose loop gain is dimensionless ?13:34
wpwrakpeople can do funny things with units, but yes, they usually refrain from making gain anything other than dimensionless :)13:41
promachso, the text is wrong about loop gain being negative ?13:42
wpwrakno, negative is fine. gain = -1: for, say, 1 V that goes in, -1 V (negative voltage) come out.13:54
promachthen for http://i.imgur.com/6g66u3U.png , why 'one plus loop gain' does not consider the negative gain provided by the common-source structure of mosfet M2  ?13:57
DocScrutinizer05promach: umm, that indeed looks a tad strange, in figure b) the circuit operates outside its nominal range22:07
DocScrutinizer05I'd apply e.g. VFF/2 to Vin, instead of grounding input22:08
DocScrutinizer05depending on type of MOSFET you want a input bias for that circuit to work22:09
DocScrutinizer05for negative resistance, see tunnel diodes22:16
DocScrutinizer05https://en.wikipedia.org/wiki/File:Voltage_controlled_negative_resistance.svg red range = negative resistance22:17
DocScrutinizer05actually tunnel diodes are used as active element in microwave oscillators22:18
DocScrutinizer05you just need a PCB antenna structure (plus horn maybe) for the resonator circuit, plus a series resistor and the tunnel diode22:19
DocScrutinizer05https://en.wikipedia.org/wiki/File:10Gig_Tunnel_Amp_M.jpg  :-)22:21
--- Wed Jun 28 201700:00

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