Amplifier Circuits:  High Frequency / High Speed Circuits / Wide Band Circuits
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Last Updated on: Sunday, July 27, 2008 07:38 PM
 

Circuits Designed by Dave Johnson, P.E. :

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.

20MHz VCSEL 3mW LASER TEST CIRCUIT This circuit takes advantage of some new vertical cavity surface emitting lasers (VCSEL) that don’t require light output control circuits. The circuit shows how to drive the device from a single high speed CMOS IC. The circuit can easily be modified to transmit signals from kilohertz to about 50MHz.

BROAD BAND 5MHz OPTICAL FIBER RECEIVER This circuit is a simple broad band light detector that uses a very inexpensive IC and a PIN photodiode that is packaged for use with plastic optical fibers. It has a bandwidth from 1KHz to over 5MHz.  It is great for experimenting with various modulated light sources.

BROAD BAND 2MHz OPTICAL FIBER RECEIVER If you need more sensitivity than the above circuit this circuit provides about ten times more gain. It too is designed around an inexpensive plastic optical fiber detector.

CMOS Logic Inverter Amplifier Characteristics This chart shows some of the measured characteristics of three different unbuffered CMOS logic gates, used as voltage amplifiers.

C-MOS INVERTER MAKES LOW POWER AMP With the addition of one resistor and a capacitor, some common logic ICs can be transformed from digital to analog duties.  This circuit outlines some the features to expect from different inverter ICs.

FET INPUT HIGH SPEED LIGHT DETECTOR This circuit is yet another design that converts current from a PIN photo diode to a voltage.   It has a bandwidth that extends beyond 50MHz.

N-CH AND P-CH TRANSISTORS FORM PUSH-PULL DRIVER This circuit can produce high speed output signals with fast rise and full times. The unique change pump action allows the voltage of the upper P-ch device to range from millivolts to hundreds of volts. The output current is only limited by the rating of the transistors. I have used this circuit beyond 2MHz.

WIDE BAND ZERO CROSS DETECTOR This circuit was designed to convert a low amplitude 40KHz signal into a clean square wave signal.  It will work with inputs as small as 5mv peak-to-peak or as large as 3 volts peak to peak.  The input frequency can range from a few kilohertz to about 150KHz.