I want to combine a 200mA DC current and a 10mA AC current at 1kHz using a bias tee. What values of inductance and capacitance should I use in the bias tee? Also, is there a way to observe the output on an oscilloscope without affecting current supply.

 

A current source needs a load.
What is that load?

Or are they really two voltage sources?

 

A current source needs a load.
What is that load?

Or are they really two voltage sources?

Two current sources to a Laser diode, one DC other AC. Diode resistance is not known but it can take maximum current uptp 250mA

 

What is the source impedance for the two current sources?
If they both are reasonably high, then you just need to connect the two sources together.

 

I want to combine a 200mA DC current and a 10mA AC current at 1kHz using a bias tee. What values of inductance and capacitance should I use in the bias tee? Also, is there a way to observe the output on an oscilloscope without affecting current supply.

Do you have a datasheet on the bias tee? I'm curious.

 

What is the source impedance for the two current sources?
If they both are reasonably high, then you just need to connect the two sources together.

So no bias Tee needed if impedence are high? What id impedence are low any method to approach and how big impedence should be tovconsider it high?

 

Do you have a datasheet on the bias tee? I'm curious.

Sorry no but i have to make bias Tee. I will add AC current is holland type

 

I want to combine a 200mA DC current and a 10mA AC current at 1kHz using a bias tee. What values of inductance and capacitance should I use in the bias tee? Also, is there a way to observe the output on an oscilloscope without affecting current supply.

Additional - Ac current is holland type

 

Sorry no but i have to make bias Tee. I will add AC current is holland type

Okay.
Pulling teeth here.
What is the DC current source?

 

Okay.
Pulling teeth here.
What is the DC current source?

Libbrecht and Hall type current controller of 200mA

 

Typical Bias Tee laser (adding DC and AC current by Bias T) The general idea.
https://www.gquipment.com/img/cms/Blog/Bias-T-applications/Baising-laser-diode.png

Noise reduction of a Libbrecht–Hall style current driver

On page 2 Jim Williams and assigned affiliates describe the nature of basic laser current supply.
AN90 - Current Sources for Fiber Optic Lasers: A Compendium of Pleasant Current Events

 

The Libbrecht and Hall driver has an input for modulation (your 1Khz AC signal). Look at the left column on the last page.

-Rick

 

The Libbrecht and Hall driver has an input for modulation (your 1Khz AC signal). Look at the left column on the last page.

-Rick

yes but i have to not use that part insteas use bias Tee

 

yes but i have to not use that part insteas use bias Tee

Why? Is this a requirement of the homework assignment?

 

Why? Is this a requirement of the homework assignment?

NO a project. Other method than Bias Tee i see create a passive impedence matching circuit but i have not understood that

 

A bias tee is not necessary. The driver circuit already includes everything you need. It modulates the current to the laser diode when you apply the AC signal.

 

It you add about a 200mH inductor in series with the DC current output to provide a high impedance to the 1kHz signal, then connecting the AC current driver directly to that connection going to the laser, should work.

 

The driver circuit already includes everything you need. It modulates the current to the laser diode when you apply the AC signal.

True.
But that's not a constant-current drive for the AC

 

It you add about a 200mH inductor in series with the DC current output to provide a high impedance to the 1kHz signal, then connecting the AC current driver directly to that connection going to the laser, should work.

I have bought 100µH to put at end of DC circuit, ok i will bought new one of 200mH. There should be need to put capacitor at end AC circuit to filter DC present in AC?

 

I have bought 100µH to put at end of DC circuit, ok i will bought new one of 200mH. There should be need to put capacitor at end AC circuit to filter DC present in AC?

Don't see the need for any capacitors as long as the voltage is just the Laser diode voltage.