Hi all,

I am learning about mixers recently. I've saw some paper using Schottky didoes in mixers but not PIN diodes. Why aren't PIN diodes a good choice for mixer design? What aspects of PIN diodes fail in mixers?

Could anyone help me with this concept?

Thanks

 

Mainly speed. PIN diodes are typically rather slow.

 

Mainly speed. PIN diodes are typically rather slow.

Thanks for the reply!

How would the diode switching speed affect mixer performance? Is it affecting the linearity because switching time relates to off-state capacitance? Could you please provide more details?

 

The diodes need to be able to turn on and off at the LO rate. If they can't do that, there will be no mixing.

 

Schottky diodes (a majority carrier only device) have almost no recombination in the depleted zone so there is no diffusion capacitance (unlike PN junctions or the PIN I region) only diode barrier resistance during switching.

 

The diodes need to be able to turn on and off at the LO rate. If they can't do that, there will be no mixing.

Besides switching speed, what diode characteristics would be important? Schottky diodes do not have recovery time (as I know). PIN diodes does gives low harmonic distortion, right? and PIN didoes can switch pretty fast too.

Also, isn't the switching time of diodes varies for different process too?