Abstract: Embodiments of the present invention provide RFID systems having battery-assisted, Semi-Passive RFID tags that operate with sensitive transistor based square law tag receivers utilizing a plurality of tag receiver dynamic range states. Embodiments of the present invention are also enhanced with receiver training and synchronizing methods suited to the high tag sensitivity and need for dynamic range state switching. These enhancements may employ pseudo-random sequence based receiver training, activation signaling, and frame synchronizing. Further enhancement is achieved via design of system command sets and tag state machine behavior that control system interference and allow maximum usage of high sensitivity. Command set design also allows for convenient expansion to active transmitters and receivers in tags operating within the same system.

Abstract: A method for controlling RF power within an RFID system according to one embodiment includes returning a first set of RFID tags that were successfully accessed at a first reader forward mode power level to a hibernate state; initiating a timer operation in each of the RFID tags within the first set of RFID tags, the timer operation defining a period of time; and preventing the first set of RFID tags from responding to an activation command at a second reader forward power level during the period of time, the second reader forward power level being higher than the first reader forward power level; and wherein a flag state stored in each of the RFID tags within the first set of RFID tags indicates whether the timer operation is active to prevent undesired activation at the second reader forward power level.

Abstract: Embodiments of the present invention provide for enhanced RFID tag receiver training and synchronizing methods suited to the high tag sensitivity that results from use of transistor detector based square law tag receivers and tag hibernation to maximize battery life. These enhancements may employ pseudo-random sequence based receiver training, activation signaling, and frame synchronizing. Embodiments of the present invention also provide RFID systems having battery-assisted, Semi-Passive RFID tags that operate with sensitive tag receivers utilizing a plurality of tag receiver dynamic range states. Further enhancement is achieved via design of system command sets and tag state machine behavior that control system interference and allow maximum usage of high sensitivity. Command set design also allows for convenient expansion to active transmitters and receivers in tags operating within the same system.

Abstract: Embodiments of the present invention provide for RFID systems that employ a plurality of battery assisted semi-passive and semi-active RFID tags with optimized system operation. The RFID tags feature receivers operating with multiple dynamic range states with square law mode for improved sensitivity, and part time active transmit in the tag to supplement its backscatter transmitter and thus support system operation taking full advantage of the sensitivity of the tag. In certain embodiments of the invention, tag sensitivity and reliability are further enhanced by the use pseudo-random sequence based receiver training and frame synchronizing.

Abstract: Specialized battery assisted command set design methods are disclosed that provide for interference rejection using highly sensitive but relatively broadband RFID tags. The command set design also supports RFID system RF power control for further interference control. The command set design also allows for convenient expansion to active transmitters and receivers in tags operating within the same system. Embodiments of the present invention provide RFID systems having battery-assisted, Semi-Passive RFID tags that operate with sensitive transistor based square law tag receivers utilizing a plurality of tag receiver dynamic range states. Additional enhancement attained via power leveling methods that optimize the amount of transmitted power and interference from a reader in relation to the sensitivity of the RFID tags, their ranges from the reader, and the unique physics of the backscatter RFID radio link.

Abstract: The present invention discloses battery assisted RFID system RF power control implementations that optimize the amount of transmitted power and interference from a reader in relation to the sensitivity of the RFID tags, their ranges from the reader, and the unique physics of the backscatter RFID radio link. Tag transmit power control implementations are also disclosed. These methods enhance system reliability when employing battery assisted RFID tags that operate with sensitive transistor based square law tag receivers and highly sensitive RFID readers intended to take advantage of outstanding tag sensitivity. Further enhancement is achieved via implementation of specialized commands that optimally support the power control operations, otherwise control system interference, and allow maximum usage of high sensitivity in both tags and readers.

Abstract: The present invention discloses battery assisted RFID system RF power leveling methods that optimize the amount of transmitted power and interference from a reader in relation to the sensitivity of the RFID tags, their ranges from the reader, and the unique physics of the backscatter RFID radio link. These methods enhance system reliability when employing battery assisted RFID tags that operate with sensitive transistor based square law tag receivers and highly sensitive RFID readers intended to take advantage of outstanding tag sensitivity. Further enhancement is achieved via design of system command sets and tag state machine behavior that optimally support the power level operations, power level operations that span across tag hibernation and normal modes, and that otherwise control system interference. Embodiments of the present invention are also enhanced with receiver training and synchronizing methods suited to the high tag sensitivity and need for dynamic range state switching.

Abstract: Specialized battery assisted command set design methods are disclosed that provide for interference rejection using highly sensitive but relatively broadband RFID tags. The command set design also supports RFID system RF power control for further interference control. The command set design also allows for convenient expansion to active transmitters and receivers in tags operating within the same system. Embodiments of the present invention provide RFID systems having battery-assisted, Semi-Passive RFID tags that operate with sensitive transistor based square law tag receivers utilizing a plurality of tag receiver dynamic range states. Embodiments of the present invention are also enhanced with receiver training and synchronizing methods suited to the high tag sensitivity and need for dynamic range state switching. These enhancements may employ pseudo-random sequence based receiver training, activation signaling, and frame synchronizing.

Abstract: Specialized battery assisted command set design methods are disclosed that provide for interference rejection using highly sensitive but relatively broadband RFID tags. The command set design also supports RFID system RF power control for further interference control. The command set design also allows for convenient expansion to active transmitters and receivers in tags operating within the same system. Embodiments of the present invention provide RFID systems having battery-assisted, Semi-Passive RFID tags that operate with sensitive transistor based square law tag receivers utilizing a plurality of tag receiver dynamic range states. Additional enhancement attained via power leveling methods that optimize the amount of transmitted power and interference from a reader in relation to the sensitivity of the RFID tags, their ranges from the reader, and the unique physics of the backscatter RFID radio link.

Abstract: Embodiments of the present invention provide for RFID systems that employ a plurality of battery assisted semi-passive and semi-active RFID tags with optimized system operation. The RFID tags feature receivers operating with multiple dynamic range states with square law mode for improved sensitivity, and part time active transmit in the tag to supplement its backscatter transmitter and thus support system operation taking full advantage of the sensitivity of the tag. In certain embodiments of the invention, tag sensitivity and reliability are further enhanced by the use pseudo-random sequence based receiver training and frame synchronizing.

Abstract: A microcontroller having digital to frequency converter and pulse frequency modulator capabilities. The digital to frequency converter (DFC) generates a 50 percent duty cycle square wave signal that may be varied in frequency, wherein the 50 percent duty cycle square wave signal is directly proportional and linear with a count value put into an increment register. The pulse to frequency modulator (PFM) generates pulses having pulse widths of the input clock for each rollover of a counter. The frequency of these pulses is directly proportional and linear with the count value put into the increment register.

Abstract: A processing unit, preferably a RISC based microcontroller, is coupled to a processing unit voltage regulator. The processing unit voltage regulator is used for controlling an operating voltage of the processing unit. A control unit is coupled to the processing unit voltage regulator and to the processing unit for setting a regulated voltage level for the processing unit voltage regulator. A voltage supply coupled to the control unit and to the processing unit voltage regulator is provided and is used for supplying the operating voltage for the processing unit wherein the operating voltage will have an upper and lower operating voltage level and an voltage supply operating range of approximately two to eighteen volts with relatively little variation in operating current.

Abstract: A new control circuit for a watchdog timer which is incorporated on the same integrated circuit as a microprocessor or microcontroller. The control circuit permits either permanent or software enablement or disablement of the watchdog timer depending on the operating mode of the microprocessor.

Abstract: An input circuit for minimizing power consumption in connected circuits is implemented. The input buffer has a saturating amplifier with a gain greater than unity, which provides for rapid transition of slowly rising or slowly falling inputs, thereby minimizing the time interval of the cross conduction range. The input buffer also has a current source which provides a constant current that limits the current when the input is within the cross conducting range. This invention is especially useful for inputs which are slowly falling or rising, where connected output circuits may be in the cross-conducting range for extended periods.

Abstract: A signal discriminator for preventing activation by undesired signals of low power transponder circuits in a keyless entry system. These undesired signals may be noise or interfering signals. An asymmetrical low pass filter is used to determine the presence of a desired signal having a defined length of time. The asymmetrical filter has a longer charge time then discharge time, thereby being adapted to quickly discharge upon the loss of a signal. Signal duration verification is further used to determine if the desired signal is of a correct time duration.