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Schottky diodes for RF application

Started by amal banerjee December 9, 2019
Could someone here shed some light on this ?
I am experimenting with envelope detection at 
RF frequencies with SPICE. The mixer is a simple 
SPICE B signal source as B0  3 4 V(1)*V(2) where
1, 2 are the nodes at which the two signal 
sources are attached. THe mixer output is fed into 
a Schottky diode(1N5818, BAR42 etc.,) and a shunt 
capacitor is attached to the Schottky diode cathode. 
However, the diode input signal looks identical to 
the output - no envelope is detected. So, could 
someone suggest some Schottky diodes that might 
work at 100 MHz - 500 MHz range, and where could 
I get their SPICE device models.
Thanks in advance for your help.
  
Do you have an inductor to ground on the door input? And capacitor resistor on output?
amal banerjee wrote:
> Could someone here shed some light on this ? > I am experimenting with envelope detection at > RF frequencies with SPICE. The mixer is a simple > SPICE B signal source as B0 3 4 V(1)*V(2) where > 1, 2 are the nodes at which the two signal > sources are attached. THe mixer output is fed into > a Schottky diode(1N5818, BAR42 etc.,) and a shunt > capacitor is attached to the Schottky diode cathode. > However, the diode input signal looks identical to > the output - no envelope is detected. So, could > someone suggest some Schottky diodes that might > work at 100 MHz - 500 MHz range, and where could > I get their SPICE device models. > Thanks in advance for your help. >
It's not likely that a different diode will help. You can't just throw something together and expect it to work. For starters, tell us the frequencies and the amplitudes of your sources. Jeroen Belleman
On Mon, 9 Dec 2019 02:47:29 -0800 (PST), amal banerjee
<dakupoto@gmail.com> wrote:

>Could someone here shed some light on this ? >I am experimenting with envelope detection at >RF frequencies with SPICE. The mixer is a simple >SPICE B signal source as B0 3 4 V(1)*V(2) where >1, 2 are the nodes at which the two signal >sources are attached. THe mixer output is fed into >a Schottky diode(1N5818, BAR42 etc.,) and a shunt >capacitor is attached to the Schottky diode cathode. >However, the diode input signal looks identical to >the output - no envelope is detected. So, could >someone suggest some Schottky diodes that might >work at 100 MHz - 500 MHz range, and where could >I get their SPICE device models. >Thanks in advance for your help. >
What's your frequency? Power schottkies have huge capacitances, basically a short at RF. We use tiny low-barrier RF schottkies, like SMS7621 or BAT15 for fast RF detection and switching. We did a signal detector recently for our I/Q modulator project. We thought it would be cool to light up LEDs when the customer applied a carrier. http://www.highlandtechnology.com/DSS/P348DS.shtml https://www.dropbox.com/s/0yysocb7cxp4bxu/P348_RF_Detector.jpg?raw=1 I have Spice sims for that somewhere. Oh, here it is: https://www.dropbox.com/s/2gkt4yzgzfbvw2v/SMS7621.asc?dl=0 -- John Larkin Highland Technology, Inc lunatic fringe electronics