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RFID Circuits, Page 1
RFID Circuits: #'s - N M - Z
Last Updated on: Friday, March 12, 2010 12:07 PM

Circuits Designed by Dave Johnson, P.E.:

CMOS INVERTER 125KHz LC OSCILLATOR
This circuit uses a single CMOS inverter to form a series resonant LD oscillator. The values shown set the oscillation at about 125KHz but other frequencies are possible by changing the main LC values.

CMOS INVERTERS FORM 125KHZ OSCILLATOR
This circuit is similar to schematic CMOS INVERTER 125KHz LC OSCILLATOR but inverts the LC components so the inductor is grounded. Two inverters are needed to produce the needed oscillation. Again, the values shown set the frequency at 125KHz but can be changed to produce other frequencies.

CMOS NAND GATE FORMS GATED 125KHZ OSCILLATOR
This circuit is similar to schematic CMOS INVERTER 125KHz LC OSCILLATOR but uses a NAND gate as an inverter. The gate allows the oscillator to be gated on and off. Again, the values shown set the frequency at 125KHz but can be changed to produce other frequencies.

Links to electronic circuits, electronic schematics, designs for engineers, hobbyists, students & inventors:

AN678: RFID Coil Design - Microchip Application Note Published 29-Sep-98 (app note added 2/06)

AN680: Passive RFID Basics - Microchip Application Note Published 13-Apr-99 (app note added 2/06)

AN830: RFID Tag & COB Development Guide with Microchip's RFID Devices - Microchip Application Note Published 21-Nov-02 (app note added 2/06)

Baseband Circuits for an RFID Receiver - DN381 Design Notes (Linear Technology) (app note added 1/06)

CMOS Inverter 125kHz LC Oscillator - This circuit uses a single CMOS inverter to form a series resonant LD oscillator. The values shown set the oscillation at about 125KHz but other frequencies are possible by changing the main LC values ….(designed by David A. Johnson)

CMOS Inverters Form 125kHz Oscillator - This circuit is similar to schematic CMOS INVERTER 125KHz LC OSCILLATOR but inverts the LC components so the inductor is grounded. Two inverters are needed to produce the needed oscillation. Again, the values shown set the frequency at 125KHz but can be changed to produce other frequencies. ….(designed by David A. Johnson)

CMOS Nand Gate Forms Gated 125kHz Oscillator - This circuit is similar to schematic number 116 but uses a NAND gate as an inverter. The gate allows the oscillator to be gated on and off. Again, the values shown set the frequency at 125KHz but can be changed to produce other frequencies. ….(designed by David A. Johnson)

Designing LF Talkback for a Magnetic Base Station - Microchip Application Note Published 5-Mar-04 (app note added 2/06)

Low Power RFID Transponder - For some time railroad companies have been wrestling with the problem of tracking rail cars. This has traditionally required manual log entry of identification numbers displayed on the cars as they pass through the switching yard….(diagram added 7/03)

RFID Circuits: #'s - N M - Z