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Transimpedance Amplifier
Circuits, Page 1
10MHz TO 20MHz LASER LIGHT DETECTOR
This circuit was originally designed to detect laser light pulses for an optical
Ethernet communications system. It has good ambient light immunity.
1uS LIGHT PULSE RECEIVER PLUS POST AMP
This circuit is designed to detect very weak light pulses lasting 1uS. It uses a
tuned LC feedback network to provide high sensitivity while giving high ambient
light immunity. A post voltage amplifier is included with a gain of about X20. The
circuit is described in more detail in the receiver section of my
Handbook of Optical Through the Air Communications. Note: The LF357 op amp
is no longer available, this circuit is for reference only.
40KHz
LASER BURST DETECTOR
This circuit was originally designed to detect weak flashed of laser light bounced off
of a fabric video projection screen. It was used as part of a firearm training system.
It generates a 100mS output pulse whenever it detects a 3ms to 5ms-laser burst,
modulated at 40KHz. It is very sensitive and could be modified for long-range laser
communications.
40KHz
LIGHT RECEIVER IS IMMUNE TO AMBIENT LIGHT
If you want even more sensitivity than the above circuit, try this design. When used
with a one-centimeter square photodiode, you can achieve a range of several hundred feet
with a standard TV or VCR remote control module.
40KHz
MODULATED LIGHT DETECTOR
This circuit uses a unique cascode amplifier circuit to convert the current from a PIN
photo diode to a current without any feedback network. It is very stable and very
sensitive. The circuit shown has the potential for a conversion factor of 10 volts per
microwatt at 900nm. I included a simple JFET post-amplifier with a gain of about 20.
