lm13700 as a voltage controlled current source

Thread Starter

myil

Joined May 2, 2020
142
Hi Everyone,

I would like to use lm13700 as a voltage controlled current source with gm=100us.
Can anybody help me how to bias it correctly?

Best regards
 

Jerry-Hat-Trick

Joined Aug 31, 2022
208
What input voltage range? What current do you want?
Perhaps you could clarify, where is the control voltage coming from, for example is it something like zero to 5 volts coming from the center tap of a potentiometer connected between the suppl and ground, and what are you wanting the current to flow through and is that load connected on one side to the positive rail or ground?
 

Thread Starter

myil

Joined May 2, 2020
142
I have been studying Christophe Basso's feedback loop design. He has designs with OTA and I found lm13800 on Proteus so I thought I could use it. I replaced a generic current source instead op amp which worked fine but It would be great if I can bias and use lm13700.
 

ericgibbs

Joined Jan 29, 2010
16,803
hi myil.
I have the LM13700 LTspice model that I use.
Post your basic circuit and the required project specification and I will create a sim circuit.
E
 

ronsimpson

Joined Oct 7, 2019
2,540
What input voltage range? What current do you want?
I want a variable current source depending on the input voltages.
Input voltage 0 to 5V.
Output voltage 0 to 100 amps. (mA, uA??)
What is the load like. Resistive load to ground? (5 ohms sitting on ground?)
This information is important. This circuit translates the voltage from IC2 to current in the load.

1668456972985.png
 

Thread Starter

myil

Joined May 2, 2020
142
Input voltage 0 to 5V.
Output voltage 0 to 100 amps. (mA, uA??)
What is the load like. Resistive load to ground? (5 ohms sitting on ground?)
This information is important. This circuit translates the voltage from IC2 to current in the load.

View attachment 280695
Hi ronsimpson,
Thank you for your reply. I think the idea behind it is that OTA should work as a current source depending on the difference between its negative and positive inputs.
 

Attachments

ericgibbs

Joined Jan 29, 2010
16,803
hi myil,
This LTS plot is a composite of your circuit posted requiring conversion to LM13700 and the 'C Basso' design.

In the intention being to check out your basic circuit.?

Note, for the purpose of testing, I have used the E1 Source in place of your U1.

Please post any additional information you have on the original homework question.

Also, please check my circuit for any errors or omissions.

E

EG57_ 211.png
 

Thread Starter

myil

Joined May 2, 2020
142
Then there is the Howland current source that does not require any special parts.

Why do you want to specifically use the LM13700?
Hi DickCappels,
Thank you for suggesting Howland current source. I removed the current source from the design and added the Howland current source. That works great as the generic current source in the database. But I am little bit sad that I couldn't make lm13700 work. I tried to contact with Texas instruments but sadly they didn't offer any support but pointing me to read datasheet.
 
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