Hello guys,
I'm trying to found out Av1(gain from Q4) of the schematic below.
I thought this would be -(RinQ3//R4)/(reQ4+R7).
with RinQ3 = (BetaQ3+1).reQ2 = BetaQ3*26mV/IcQ3.
Took BetaQ3 as 300 and IcQ3 was 6.65 mA
RinQ3 = 300*26V/6.65A~ 1K2
RinQ3//R4 ~ RinQ3
ReQ4 = 26mV/IcQ4 with IcQ4 = 0.7V/15K = 46.6µA
= 560 Ω
Av1 = -1K2/(1560Ω)=- 0.77
The LTSpice result gave me a gain which was arround 0.16..
The voltage at node4 is VcQ4
I'm unable to found out what I'm doing wrong.
Someone could help me out on this one?
Thanks in advance!!
The LTSpice file is in the att.
Original link : http://www.zen22142.zen.co.uk/Circuits/Audio/2wamp.html
I'm trying to found out Av1(gain from Q4) of the schematic below.
I thought this would be -(RinQ3//R4)/(reQ4+R7).
with RinQ3 = (BetaQ3+1).reQ2 = BetaQ3*26mV/IcQ3.
Took BetaQ3 as 300 and IcQ3 was 6.65 mA
RinQ3 = 300*26V/6.65A~ 1K2
RinQ3//R4 ~ RinQ3
ReQ4 = 26mV/IcQ4 with IcQ4 = 0.7V/15K = 46.6µA
= 560 Ω
Av1 = -1K2/(1560Ω)=- 0.77
The LTSpice result gave me a gain which was arround 0.16..
The voltage at node4 is VcQ4
I'm unable to found out what I'm doing wrong.
Someone could help me out on this one?
Thanks in advance!!
The LTSpice file is in the att.
Original link : http://www.zen22142.zen.co.uk/Circuits/Audio/2wamp.html
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