Hello,
In my quest to improve my very weak electronics skills, I thought I would give myself a project to force me to be more hands on.
I want to create a working prototype of a load transient driver using mostly discretes (transistors, MOSFET's, capacitors, resistors, etc), and a few or no IC's. The requirements would be:
Input is driven by function generator (0 to 10 V)
frequency is not too important. Low frequency is fine. Under 1 kHz.
output load is capacitive (up to 10 uF)
Would like to be able to drive this 10 uF load from 0 to 5 V in 25 us or less. My calculations show I would need:
i = C dv/dt
i= ((10u)*(5 V)) / 25 us = 2 A
No limitations on any VCC or VEE rails. Would like the output slew rates to sort of track the input so that the function generator can fine-adjust as needed.
I have some basic understanding of certain transistor topologies: common emitter, emitter followers, push-pull output stages, etc.
My initials thoughts are that after the function generator, I would needs lots of current gain. An emitter follower is the first thing that comes to mind. Or maybe use multiple stages to first boost up the gain... Current mirrors seem to make sense from an IC design point of view... not sure how good they would be when used as discretes / transistor arrays? I often see push-pull output stages used to drive low resistance loads... In this still a good idea w/ a capacitive load at low frequency? The impedance of 10 uF at 1 kHz (max frequency) is ~ 16 ohms.
Basically, I just want to brainstorm ideas, and learn the thought process from the more experienced experts on this forum. How would you tackle this problem?
Thanks!
In my quest to improve my very weak electronics skills, I thought I would give myself a project to force me to be more hands on.
I want to create a working prototype of a load transient driver using mostly discretes (transistors, MOSFET's, capacitors, resistors, etc), and a few or no IC's. The requirements would be:
Input is driven by function generator (0 to 10 V)
frequency is not too important. Low frequency is fine. Under 1 kHz.
output load is capacitive (up to 10 uF)
Would like to be able to drive this 10 uF load from 0 to 5 V in 25 us or less. My calculations show I would need:
i = C dv/dt
i= ((10u)*(5 V)) / 25 us = 2 A
No limitations on any VCC or VEE rails. Would like the output slew rates to sort of track the input so that the function generator can fine-adjust as needed.
I have some basic understanding of certain transistor topologies: common emitter, emitter followers, push-pull output stages, etc.
My initials thoughts are that after the function generator, I would needs lots of current gain. An emitter follower is the first thing that comes to mind. Or maybe use multiple stages to first boost up the gain... Current mirrors seem to make sense from an IC design point of view... not sure how good they would be when used as discretes / transistor arrays? I often see push-pull output stages used to drive low resistance loads... In this still a good idea w/ a capacitive load at low frequency? The impedance of 10 uF at 1 kHz (max frequency) is ~ 16 ohms.
Basically, I just want to brainstorm ideas, and learn the thought process from the more experienced experts on this forum. How would you tackle this problem?
Thanks!