Post subject: Laser Receiver Posted: Fri Aug 11, 2006 6:20
Joined: Fri Aug 11, 2006 6:07 am
I need to design a laser receiver circuit which would receive
laser pulses in the red region of the spectrum (around 630nm wavelegth),
the laser pulses carry an RF ripple of around 315MHz. I built a current
to voltage converter using a transimpedance amplifier with resistor
feedback and simulated it on Multisim, it seems to be working fine.
But I have a couple of problems, firstly, the transimpedance amplifier
is an inverting amplifier so I need to reinvert the signal or get it
straight the first time with minimum distortion. Secondly, I need to
find a way to have two outputs for the device, one giving the equivalent
output voltage of the signal (DC with a 315MHz ripple) and the other
with AC coupling (just the 315MHz ripple). And the last problem is that
I need to make the system as noise-immune as possibe. If anyone can
help me or point me to where I can find something that would help I'd
appreciate it a lot.
Posted: Fri Aug 11, 2006 7:55 am
Fri Feb 17, 2006 12:07 pm
Location: London UK
first reaction is try to separate the dc from the 315MHz components
at as early a stage as possible.
What is the source/spectrum of the
Posted: Fri Aug 11, 2006 8:15 am
Aug 11, 2006 6:07 am
Well, there's no specific source,
it's just thermal noise, shot noise and other regular sources of interference.
I can put two parallel transimpedance amplifiers, one to separate the
RF alone and the other just to convert the signal to voltage as a whole,
but the problem is that I get a weird transient of a relatively low
frequency whenever there's a pulse transition when I try to separate
the RF alone, I guess it's due to the presence of the L and C in the
transimpedance amplifier, I'm still trying to figure out how to remove
Post subject: Posted: Fri Aug
11, 2006 1:14 pm
Joined: Fri Aug 11, 2006 6:07
I think I was able to do it but I just have one more
question left. I'm supposed to add an enable signal to the circuit,
what would be the best way to implement that? Is it through a transistor
that passes Vcc to the whole circuit when it receives the needed signal
or through a transistor that passes the output signal when it receives
the enable signal?
Post subject: Posted:
Fri Aug 11, 2006 1:23 pm
Joined: Mon Jun
27, 2005 2:02 pm
To answer to your last question, I recommend to use the first option,
i.e. to control over the Vcc supply voltage. This will promise a full
isolation and will block any leakage or residual signals to the output.