Efficient charge pump apparatus and method

• US 20060202828A1
• Filed: 05/17/2006
• Published: 09/14/2006
• Est. Priority Date: 02/12/2001
• Status: Active Grant

• Current Assignee: Symbol Technologies, LLC (Zebra Technologies Corporation)
• Original Assignee: Symbol Technologies, Inc. (Zebra Technologies Corporation)
• Inventors: Bandy, William R., Powell, Kevin J., Shanks, Wayne E., Arneson, Michael R.
• Granted Patent: US 7,564,358 B2
• Time in Patent Office: Days
• US Class Current: 340/572.100
• CPC Class Codes: G06K 17/00 Methods or arrangements for effecting co-operative working between equipments covered by two or more of main groups G06K1/00 - G06K15/00, e.g. automatic card files incorporating conveying and reading operations
• CPC Class Codes: G06K 19/0713 the arrangement including a power charge pump
• CPC Class Codes: G06K 19/0723 the record carrier comprising an arrangement for non-contact communication, e.g. wireless communication circuits on transponder cards, non-contact smart cards or RFIDs
• CPC Class Codes: G06K 19/07749 the record carrier being capable of non-contact communication, e.g. constructional details of the antenna of a non-contact smart card
• CPC Class Codes: G06K 19/07767 the first and second communication means being two different antennas types, e.g. dipole and coil type, or two antennas of the same kind but operating at different frequencies
• CPC Class Codes: G06K 7/0008 General problems related to the reading of electronic memory record carriers, independent of its reading method, e.g. power transfer
• CPC Class Codes: G06K 7/10039 interrogator driven, i.e. synchronous
• CPC Class Codes: G06K 7/10069 the collision being resolved in the frequency domain, e.g. by hopping from one frequency to the other frequency hopping or spread spectrum techniques H04B7/00
• CPC Class Codes: G06K 7/10108 interrogating only those RFIDs that fulfill a predetermined requirement, e.g. selecting all RFIDs having the same speed and moving in a cloud like fashion, e.g. on the same train; interrogating only RFIDs having a certain predetermined temperature, e.g. in the same fridge, another possibility being the active ignoring of a group of tags that fulfill a predetermined requirement, equivalent to the Boolean NOT operation
• CPC Class Codes: G06K 7/10356 using a plurality of antennas, e.g. configurations including means to resolve interference between the plurality of antennas
• CPC Class Codes: G08B 13/2485 Simultaneous detection of multiple EAS tags
• CPC Class Codes: G11C 5/142 Contactless power supplies, e.g. RF, induction, or IR
• CPC Class Codes: H04L 7/0331 with a digital phase-locked loop [PLL] processing binary samples, e.g. add/subtract logic for correction of receiver clock H04L7/0337 takes precedence

Abstract

An identification (ID) tag includes a substrate having an input capable of receiving a high frequency signal. For instance, the high frequency signal can be a radio frequency (RF) signal that is generated as part of a radio frequency (RF) ID system. A first charge pump is coupled to the input and is configured to convert the high frequency signal to a substantially direct current (DC) voltage. A data recovery circuit is coupled to the input and is capable of recovering data from the high frequency signal. A back scatter switch is coupled to the input and is capable of modifying an impedance of the input, responsive to a control signal. A state machine is disposed on the substrate and is responsive to the data recovered by the second charge pump, where the state machine is capable of generating the control signal for the back scatter switch in response to the data. The DC voltage from the first charge pump is capable of providing a voltage supply for at least one of the data recovery circuit, the back scatter switch, and the state machine. The data recovery circuit includes a second charge pump that is capable of operating on the high frequency signal simultaneously with the first charge pump. In other words, the first charge pump can generate the supply voltage for the ID tag from the high frequency signal, while the second charge pump simultaneously retrieves the data from the high frequency signal. The first charge pump also includes a means for limiting the amplitude of the DC voltage by reducing the charge pump efficiency, once a threshold voltage is reached.

Claims

1-28. -28. (canceled)

29. A method of operating a charge pump having a plurality of stages, comprising:

receiving a radio frequency (RF) signal at an input of the charge pump;

generating a substantially direct current voltage using the plurality of stages of the charge pump responsive to the RF signal; and

providing the substantially direct current voltage to a radio frequency identification tag.

30. The method of claim 29, wherein the generating and the providing steps are performed on a common substrate.

31. The method of claim 29, wherein the step of generating the substantially direct current voltage includes rectifying the RF signal using the plurality of stages.

32. The method of claim 29, wherein the step of generating the substantially direct current voltage includes:

storing a first charge of the received RF signal in a first stage of the plurality of stages;

storing a second charge of the received RF signal in a second stage of the plurality of stages; and

combining the first charge and the second charge in a third stage of the plurality of stages.

33. The method of claim 32, wherein the step of combining the first charge and the second charge includes combining the first charge and the second charge to provide a voltage greater than an amplitude of the received RF signal.

34. The method of claim 32, wherein the step of generating the substantially direct current voltage further includes:

accumulating the first charge during a first half-cycle of the received RF signal; and

accumulating the second charge during a second half-cycle of the received RF signal.

35. The method of claim 29, further including the step of removing a portion of a charge accumulated from the received RF signal in response to the charge reaching or exceeding a threshold.

36. The method of claim 35, wherein the step of removing the portion of the charge includes shunting the portion of the charge to ground.

37. The method of claim 29, wherein the step of generating the substantially direct current voltage includes providing the received RF signal to a plurality of capacitors connected in parallel.

38. The method of claim 29, wherein the step of generating the substantially direct current voltage includes manipulating the received RF signal using a metal oxide field effect transistor having a body, a gate, and one of a source and a drain connected together.

39. A charge pump apparatus, comprising:

an input to receive a radio frequency (RF) signal; and

a plurality of stages, each stage including a means for rectifying the RF signal to generate a substantially direct current voltage based on the received RF signal, the substantially direct current voltage to be utilized by a radio frequency identification tag.

40. The apparatus of claim 39, wherein each stage further includes:

means for storing a first charge of the RF signal;

means for storing a second charge of the RF signal; and

means for combining the first charge and the second charge.

41. The apparatus of claim 40, wherein the means for combining the first charge and the second charge includes the means for combining the first charge and the second charge to provide a voltage greater than an amplitude of the RF signal.

42. The apparatus of claim 39, wherein each stage further includes

means for accumulating the first charge during a first half-cycle of the RF signal;

and

means for accumulating the second charge during a second half-cycle of the RF signal.

43. The apparatus of claim 39, each stage further including a means for removing a portion of a charge accumulated from the RF signal in response to the accumulated charge reaching or exceeding a threshold.

44. The apparatus of claim 43, wherein the means for removing the portion of the accumulated charge includes a means for shunting the portion of the charge to ground.

45. The apparatus of claim 39, wherein the means for rectifying the RF signal includes a metal oxide field effect transistor having a body, a gate, and one of a source and a drain connected together.

46. The apparatus of claim 39, wherein the means for rectifying the RF signal includes a metal oxide field effect transistor having a body and one of a source and a drain connected together.

47. A charge pump, comprising:

a charge pump input;

a plurality of stages parallel connected to said charge pump input, each stage having a first capacitor connected between said charge pump input and a central node, a first diode having an anode coupled said central node and a cathode coupled to a second node, a second diode having an anode coupled to said second node in a prior stage and a cathode coupled to said central node; and

a charge pump output coupled to said second node in a last stage of said plurality of stages.