Continue to Site

Welcome to our site!

Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

  • Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

Diodes

Status
Not open for further replies.

hykwei

New Member
Hi guys

if i want to clamp a 10MHz, 2V p-p sinusoidal signal at +-400mV, what is the easiest way of doing this?

At the moment i am using the properties of diodes (1N4148, 0.7V volt drop), which succesfully clamp the signal @ +-0.7V. but it is stll higher than the siganl that i want (+-0.4V)

I am now thinking using some fast schottky diodes, which has got a lower voltage drop. But i do not know what other schottky diodes are availabe? (The only schottky diode that i know is 1N5819...)

Thanks
 
i hav thought about that, but for that way it's going to introduce more phase shift to the output signal...which is what i m trying to avoid...

it will be great if i can clamp the signal in just one stage!
 
And how does a resistive attenuator introduce phase shift?
 
Hi Hykwei

JimB said:
And how does a resistive attenuator introduce phase shift?

I was going to ask the same question but you beat me to it.

About the diodes you could use BAT81 . . . 83 or the BAT85 which has
an even lower forward voltage drop. Other possible candidates are
1N5711 & 12 and the 5082-2300, 5082-2800 and 5082-2900.

on1aag.
 
well...that is what i observed from the output of the attenuator...it does introduce more phase shift when i compare the input and output using oscilloscope...

i suppose every components(even resistor) has got internal capacitance, and under a high frequency system (MHz range), those capacitance becomes more significant + introducing phase shift, doesn't it?

This is what i think...please correct me if m wrong!

Thanks
 
hykwei said:
well...that is what i observed from the output of the attenuator...it does introduce more phase shift when i compare the input and output using oscilloscope...

i suppose every components(even resistor) has got internal capacitance, and under a high frequency system (MHz range), those capacitance becomes more significant + introducing phase shift, doesn't it?

This is what i think...please correct me if m wrong!

Look at how a scope x10 probe works!, or the switched attenuator inside the scope!.

What value resistors were you using, and what were the source and load impedances.
 
hykwei said:
the resistor value is 20k...is that too large?

Probably far too large, and why only one resistor?, you need two for an attenuator.

Also, are you using a x10 probe on the scope?, the scope capacitance will cause phase shift with your large resistor.
 
Status
Not open for further replies.

Latest threads

New Articles From Microcontroller Tips

Back
Top