bachevelle52
Active member
- Joined
- May 23, 2009
- Messages
- 43
I'd like to build an instrument input for the front end of a micamp. While i've FINALLY started to understand how a transister (bjt) works from a purely theoretical and not very scientific point of view, I still know essentially nothing with regard to applying that theoretical knowledge.
My GOAL then would be to design a discrete impedance buffer/phase splitter, considering the following;
1. My intended load would be an amp based on the INA217 and the circuit recomendation found in it's datasheet.
2. I considered using an op-amp as a buffer, however given the differential input of the 217 unless i used a dual op-amp i would still only have one input signal.
3. Using an op-amp wouldn't teach me what i want to know.
4. I need a high impedance input (1M?) and a Low impedance (200ohm) Differential output.
This leads to a whole lot of questions.....
First, would this benefit more from using a BJT or an FET? I read in TAOLE pp.86 that as a current amplifying device, BJT's have a low input impedance and a high output impedance. Is that based on configuration, as in common base?
I found this in the same book, pp. 97 Figure 6.33:
*notated that the Ic will only differ from Ie by the loss of the base current. I can live with that. Can someone nudge me in the right direction here?
My GOAL then would be to design a discrete impedance buffer/phase splitter, considering the following;
1. My intended load would be an amp based on the INA217 and the circuit recomendation found in it's datasheet.
2. I considered using an op-amp as a buffer, however given the differential input of the 217 unless i used a dual op-amp i would still only have one input signal.
3. Using an op-amp wouldn't teach me what i want to know.
4. I need a high impedance input (1M?) and a Low impedance (200ohm) Differential output.
This leads to a whole lot of questions.....
First, would this benefit more from using a BJT or an FET? I read in TAOLE pp.86 that as a current amplifying device, BJT's have a low input impedance and a high output impedance. Is that based on configuration, as in common base?
I found this in the same book, pp. 97 Figure 6.33:
*notated that the Ic will only differ from Ie by the loss of the base current. I can live with that. Can someone nudge me in the right direction here?