Hi all, first post here..
I think that the questions I'm about to ask could have been set even in the Electronics Chat forum , but I understand they're more related to the basic scheme of how does something work.
I found a quite weird VCA in a synthesizer: it's called iG00151 , made by Yamaha; unfortunately they never have released the datasheet of it and I'd like to try and understand what's the deal about it. I have a block diagram of it here below, named "current-voltages" : you can see that it looks like an OTA with an Expo-to-Linear converter, so it gets a voltage (green line) to output a current.
How can I do the converting calculation? Also, what's the role of the negative feedback?
Main problem for me, though, concerns the voltage calculation at the output of this VCA: see the "VCO control" picture for reference. Looking at the picture I can see the currents mix with voltages (initial pitchbend, subosc); but I need to know how to render the current's magnitude into voltage! Can anybody help me to understand what's the correct calculation at the "N" node?
Last question: what's the role of the 0.01KΩ capacitor at the VCA's output?
Thanks for any help.
Max
I think that the questions I'm about to ask could have been set even in the Electronics Chat forum , but I understand they're more related to the basic scheme of how does something work.
I found a quite weird VCA in a synthesizer: it's called iG00151 , made by Yamaha; unfortunately they never have released the datasheet of it and I'd like to try and understand what's the deal about it. I have a block diagram of it here below, named "current-voltages" : you can see that it looks like an OTA with an Expo-to-Linear converter, so it gets a voltage (green line) to output a current.
How can I do the converting calculation? Also, what's the role of the negative feedback?
Main problem for me, though, concerns the voltage calculation at the output of this VCA: see the "VCO control" picture for reference. Looking at the picture I can see the currents mix with voltages (initial pitchbend, subosc); but I need to know how to render the current's magnitude into voltage! Can anybody help me to understand what's the correct calculation at the "N" node?
Last question: what's the role of the 0.01KΩ capacitor at the VCA's output?
Thanks for any help.
Max
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