Frequency Response Heterojunction Bipolar Transistor

Thread Starter

insyspower

Joined May 29, 2017
34
that V(in) is 5mV, but i need V(in)=50mV, i got a lot of noise on the digital osciloscope for V(in) = 5mV, but for 50mV is acceptable,
 

Bordodynov

Joined May 20, 2015
3,177
First, you greatly increase the gain (gain = 1366), and then want to apply 50 mV. 50 mV * 1366 = 68.3 Volts !!!. First, determine which gain you need. I sent you a version with a gain of 290. If you change the supply voltage, then you need to adjust the mode of the output transistor. Once I offered you an amplifier with self-tuning mode. You did not like him. And now you create difficulties for yourself.
 

Thread Starter

insyspower

Joined May 29, 2017
34
i did this: .meas tran AP avg v(Vpardiferencial)
.meas tran MP max v(Vpardiferencial)

the results are: ap: AVG(v(vpardiferencial))=17.0983 FROM 0 TO 0.02
mp: MAX(v(vpardiferencial))=17.6337 FROM 0 TO 0.02

but i want if possible put the "ap" and "mp" values on the expression editor, like this:
(V(vout)-avg(V(vout)))/(max(V(vout)-avg(V(vout)))

whitout using the real values "17.09" and "17.63".

V(out) is the output signal wave of that circuit, "max" is the maximum value, "avg" is average value or mean, i don't know what syntax ltspice uses.
 

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Bordodynov

Joined May 20, 2015
3,177
No Spice will allow this. The average and maximum value can only be obtained by performing the entire calculation. LTspice does not have a time machine to display an expression with parameters that will become known in the future. So will have to make two calculations. The first calculation you will determine the average and maximum. In the second calculation, you can use the results of the first.
 
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Thread Starter

insyspower

Joined May 29, 2017
34
First, you greatly increase the gain (gain = 1366), and then want to apply 50 mV. 50 mV * 1366 = 68.3 Volts !!!. First, determine which gain you need. I sent you a version with a gain of 290. If you change the supply voltage, then you need to adjust the mode of the output transistor. Once I offered you an amplifier with self-tuning mode. You did not like him. And now you create difficulties for yourself.
i need a Gain around 300. How do i adjust the mode of output transistor? i like self-tuning mode, what post is that circuit ?
 

Thread Starter

insyspower

Joined May 29, 2017
34
Thanks.
i want determine on ltspice the FFT of V(vpardiferencial), the issue is i want to normalize the signal wave on transient, but as you can see on the image, the V(vpardiferencial) is not between 1V and -1V, so i used this expression: (V(vpardiferencial)-17.0983)/(0.53539), now its between 1V and -1V like i want, but when i do view ->FTT is impossible to put this expression on FFT, i get a ridiculous result, the problem is when i subtract 17.0983, since the FFT is in decibel, if i divide or multiply i still get the right result, so for V(viinv)*400, i get -3dB for fundamental harmonic, the same happen to V(vout)/4.5.
The V(vpardiferencial) is -8.3dB, i think i want to be close to -3dB.
I still using the old circuit.
 

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Thread Starter

insyspower

Joined May 29, 2017
34
i want to simulate the circuit on post #29, on PSpice.
On image 1hbt.png we can see that Draft4 is working fine, on image 2hbt_pardif.png is the same circuit as Draft4 but on PSpice that circuit won't work right, because on Green voltage marker the same point as vpardif on LTspice, the voltage is always 3V (3vpardif_pspice.png)
The transistor i am using is BFR92A/PLP, because on PHILRF.lib the BFR92 is not there, no model available, but BFR92A is still the complementary of BFT92 so i thought it would work on PSpice, but unfortunately yet no.

The only circuit of HBT on PSpice is working right now for me is Class B Amplifier: HBTclassB.png & HBTclassB_vout_graph.png .
 

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