| Author |
Message |
tsy85
Joined: 16 Aug 2008
Posts: 9
|
 27 Aug 2008 15:09 Envelope Detector |
|
|
|
Hi there,
I am looking for a simplest envelope detector circuit which consists of one diode,and a low pass (RC) filter.the envelope detector circuitry should be able to extract the 900MHz modulated signal.
If anyone has the schematic(with the RC value)/simulation(Agilent ADS) on the above mentioned specs,hope you could help me here as I need it urgently.
THANKS VERY MUCH!!! 
Have a nice day.
|
|
| Back to top |
|
 |
tsy85
Joined: 16 Aug 2008
Posts: 9
|
| 08 Sep 2008 21:02 Re: Envelope Detector |
|
|
|
| No one knows anything bout it?
|
|
| Back to top |
|
|
GVVIN
Joined: 11 Apr 2008
Posts: 98
Helped: 15
|
| 09 Sep 2008 2:04 Re: Envelope Detector |
|
|
|
See attached
|
|
| Back to top |
|
|
jayce3390
Joined: 22 May 2007
Posts: 95
Helped: 2
|
| 18 Sep 2008 10:14 Re: Envelope Detector |
|
|
|
Hi,
this subject interests me
Do you know what kind of OPA is able to not disturbing the detected signal due to its input impedance ?
I think it's critical .
|
|
| Back to top |
|
|
biff44
Joined: 24 Dec 2004
Posts: 1295
Helped: 168
Location: New England, USA
|
| 22 Sep 2008 13:08 Envelope Detector |
|
|
|
| That circuit does not look right to me. There is no path for DC thru the diode. As a start, I would eliminate C1, and replace C2 with a 270 ohm resistor (a good balance between sensitivity and detection speed). I would also increase the L1 value so that it had at least J200 ohms at 900 MHz.
|
|
| Back to top |
|
|
jayce3390
Joined: 22 May 2007
Posts: 95
Helped: 2
|
| 23 Sep 2008 9:19 Re: Envelope Detector |
|
|
|
after simulating at 900 Mhz (transient) :
[/img]
|
|
| Back to top |
|
|
kspalla
Joined: 19 Aug 2008
Posts: 141
Helped: 23
Location: Bangalore
|
| 25 Sep 2008 11:50 Re: Envelope Detector |
|
|
|
Hi,
The circuit is not consisting of discharge path, so it can not work with the dynamic signals.
|
|
| Back to top |
|
|
jayce3390
Joined: 22 May 2007
Posts: 95
Helped: 2
|
| 26 Sep 2008 13:09 Re: Envelope Detector |
|
|
|
THis circuit must be able to follow the RF input signal envelope, how to check its capability?
could you help me in this way?
|
|
| Back to top |
|
|
jayce3390
Joined: 22 May 2007
Posts: 95
Helped: 2
|
| 06 Oct 2008 8:52 Re: Envelope Detector |
|
|
|
| No one knows anything about it?
|
|
| Back to top |
|
|
biff44
Joined: 24 Dec 2004
Posts: 1295
Helped: 168
Location: New England, USA
|
| 06 Oct 2008 15:55 Re: Envelope Detector |
|
|
|
A diode detector can have maybe 25 dB or so of dynamic range. You want an RF Power source that can be pulse amplitude modulated. In the high power state, you want an RF signal close to the maximum signal range to be detected. In the low power (off) state you need to attenuate that maximum RF power state by at least that 25 dB, although more attenuation is ok too.
A standard microwave switch with pin diodes or fets is fine to do the pulse modulation. If you application is slow, a lot of times the RF signal generator can also be amplitude modulated to produce this RF pulse.
It is important to use an analog load that is the similar in impedance to one you will use in the final circuit. For instance, if you are using an op amp inverter for the detected video voltage, you would do the test with a high impedance oscilloscope input. This is important if you want to get an accurate view of the detector's response time.
|
|
| Back to top |
|
|
shiko
Joined: 01 Nov 2007
Posts: 7
|
| 06 Oct 2008 18:09 Re: Envelope Detector |
|
|
|
Hi all nice topics and really intresting..... i designed FM detector using envelop detector for 315Mhz carrier frequency but i have a problem for calculating RC values to get smooth audio signal ...GVVIN you simulate the reciever for 900Mhz can u help me how to get the values for 315Mhz and thnx in advance
|
|
| Back to top |
|
|
Sinisa
Joined: 03 Mar 2003
Posts: 299
Helped: 60
|
| 07 Oct 2008 3:47 Re: Envelope Detector |
|
|
|
| I made detector for 500MHz using this application note. It works great.
|
|
| Back to top |
|
|
