This invention relates to Radio Frequency IDentification (RFID) Readers and, more particularly, to adjusting parameters associated with leakage signals.
Passive UHF RFID (radio frequency identification) protocols require the tag to be powered by the reader's field and to use the field to backscatter information on the same frequency. The technical term for such a system, where both the transmit and receive sections of the device are simultaneously operating on the same frequency is “homodyne.” One class of homodyne systems intends to only transmit a pure continuous sinusoidal wave (CW) signal while in the receive mode. UHF RFID reader systems are of this class. A challenge is presented to the homodyne systems when the receiver section is not well isolated from the transmitter section. Transmitter (TX) leakage into the receive (RX) path can be as much as 110 dB above the desired backscattered receive signal. Such a high TX leakage to receive signal ratio leaves the receiver section quite susceptible to typical nonlinearities associated with standard cost effective analog signal processing components. Therefore an unusually high dynamic range in the receiver section would be required.
Passive and semi-active (battery assisted) UHF RFID communications use radar cross section (RCS) modulation to send data from the transponder to the reader. That means the reader transmits a sinusoidal RF signal toward the transponder. Some of the RF energy which hits the transponder reflects back to the reader. By modulating its RCS, the transponder is able to communicate data back to the reader.
This presents many design challenges. In particular, the reader electronics must be designed to receive a very weak signal while it is transmitting a very strong signal at the same frequency. Whereas many other wireless communications schemes use frequency division multiplexing, the RFID reader cannot since its own transmit field is being used as a medium for communications from transponder to reader. The transmit signal may be 1 watt or more, while the receive signal for semi-active transponders (those which only use the RF signal for communications, not for power) may be as low as 1 picowatt (10−12 watt), e.g., 12 orders of magnitude less power. For passive transponders the receive strength is usually at least 1 nanowatt (1031 9 watt), which is still pretty challenging.
The present disclosure includes a system and method for adjusting parameters associated with leakage signals. In some implementations, an RFID reader includes an RF antenna, a transmitter section, a receiver section, a control module and a cancellation noise reduction (CNR) section. The transmitter section is coupled to the RF antenna and operable to generate a transmit signal to be transmitted by the RF antenna. The receiver section is coupled to the RF antenna and operable to receive a receive signal from the RF antenna. In addition, the receiver section further includes a de-rotation module and a control module. The de-rotation module is operable to de-rotate, by θ, an in-phase signal and quadrature signal associated with the leakage signal. The control module is operable to generate control signals used to produce a signal for reducing the leakage signal in a receive path of the reader. The CNR section is operable to subtract the reduction signal from the leakage signal.
The details of one or more embodiments of the invention are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the invention will be apparent from the description and drawings, and from the claims.
Like reference symbols in the various drawings indicate like elements.
In some implementations, the reader 100 may estimate the transmit signal as:
x(t)=A(t)cos(2πFct+φ(t)+θ),
where A(t) represents slow amplitude variations, φ(t) represents the oscillator phase noise, and θ represents the phase angle of the transmit signal out of, for example, a power amplifier. In addition to the receive signal in the receive path, the reader may also include leakage signals in the receive path and the combination of these signals may be expressed as:
y(t)=r(t)+c(t)·A(t)cos(2πFct+φ(t)+(t)+θ),
where r(t) is the receive signal from transponders and other RF environmental signals and the rest may estimate the leakage signal from the transmitter, where, in some implementations, c(t)<<1 and 0≦(t)<2π can represent slow variations in transmit leakage amplitude and/or phase and both can vary slowly over time. During the course of this description, the leakage current is described in polar coordinates but may also be described in other coordinates such as rectangular. In some implementations, the leakage current may be expressed as a portion of an in-phase signal and a quadrature signal, as discussed in more detail below.
In the illustrated implementation, the reader 100 includes a carrier-noise-reduction (CNR) module 102, a receiver module 104, and a transmitter module 106. The CNR module 102 includes any software, hardware, and/or firmware operable to reduce leakage signals in the receive path. For example, the CNR module 102 may add signals to the receive path for canceling, minimizing, or otherwise reducing leakage signals. In the illustrated implementation, the CNR module 102 includes a power splitter 108, a quadrature modulator 110, a summer 112, a dual digital-to-analog converter (DAC) 114, and a calibration switch 116. The power splitter 108 splits or otherwise directs a portion of the transmit signal to the quadrature modulator 110. In some implementations, the portion of the transmit signal may be expressed as:
u(t)=b1·x(t),
where b1 is a fixed small constant (e.g., b1=0.05). In addition to receiving a portion of the transmit signal, the quadrature modulator 110 receives an in-phase control signal vi(t) and a quadrature control signal vq(t). In some implementations, the control signals may be polar controls. The quadrature modulator 110 can modulate the portion of the transmit signal (e.g., u(t)) and the baseband quadrature control signals vi(t) and vq(t) to generate a cancellation signal for the leakage signal. In some implementations, the quadrature modulator 110 includes a vector modulator.
In some implementations, the quadrature modulator 110 may estimate the cancellation signals as:
z(t)=b2A(t)(vi(t)cos(2πFct+φ(t)+θ)+vq(t)sin(2πFct+φ(t)+θ))
where b2 is a fixed small constant (e.g., b2=0.01). In some implementations, the constant b2 accounts for the combined signal attenuation through the power splitter (b1) and the quadrature modulator 110. In the example expression for the cancellation signal, the quadrature modulator 110 uses the input u(t) to generate a 90 degree shifted version (sine), then modulates the control signals vi(t) and vq(t) onto these cosine and sine carriers, respectively, to produce the cancellation signal.
After generating the cancellation signal, the quadrature module 110 directs the cancellation signal to the summer 112. The summer 112 subtracts the cancellation signal from the signal received from the receiver which includes the leakage signal. In the example, the summer 112 subtracts the quadrature modulator output signal z(t) from the receiver input y(t) to produce s(t). In some implementations, the residual signal s(t) substantially equals the desired receive signal r(t), i.e., substantially all of the transmitter leakage is cancelled. The CNR module 102 can represent the residual signal as:
s(t)=b2A(t)(c(t)·cos(2πFct+φ(t)+(t)+θ)+vi(t)cos(2πFct+φ(t)+θ)+vq(t)sin(2πFct+φ(t)+θ))+r(t)
In some implementations, the CNR module 102 includes the dual DAC for converting digital control signals to analog control signals and directing the analog control signals to the quadrature modulator 110. In some implementations, the control signals are generated as a sampled data signal and these signals are passed through a dual digital-to-analog converter (DAC) to create the analog control signals for the quadrature modulator 110. In other words, the control signals vi(t) and vq(t) can comprise digital signals received from the dual DAC 114. In some implementations, the control signals vi(t) and vq(t) may be generated from analog control circuitry. The calibration switch 116 can substantially prevent input signals into the receive module 104 when the DC offsets and/or the phase offsets are estimated. The reader 100 also includes a circulator 140. The circulator 140 directs the transmit signals towards the antenna and also directs receive signals from the antenna to the CNR module 102. The circulator 140 could be replaced with a coupler or separate transmit and receive antennas could be used, commonly known as a bi-static antenna configuration.
The receiver module 104 can include any software, hardware, and/or firmware operable to down convert the received signal to baseband signals for processing by the DSP 130. For example, the receiver module 104 may convert an RF signal to a baseband signal. In some implementations, the baseband signal is a low frequency signal (e.g., DC to 400 KHz). In addition, the receiver module 104 may perform other functions such as amplification, filtering, conversion between analog and digital signals, and/or others. The receiver module 104 may produce the baseband signals using a mixer and low pass filters. In the illustrated implementations, the receiver module 104 includes a low noise amplifier (LNA) 118, a mixer 120, a low pass filters (LPFs) 122 and 124, and a dual ADC 126. The LNA 118 receives the residual signal from the summer 112 and amplifiers the residual signal in light of the relative weakness of the signal to the transmission signal. The mixer 120 mixes the residual signal with a signal received from a frequency synthesizer 128 to generate two component signals. In the illustrated implementation, the mixer 120 generates an in-phase signal and a quadrature signal. For example, the receiver module 104 can amplify the residual signal s(t) using the LNA 118 and then mix down the signal to baseband using a combination of the quadrature mixer 120 and the LPFs 122 and 124. The LPFs 122 and 124 can reject the out of band energy of transceivers in neighboring channels. In doing so, the effect of out of band noise can be made relatively small through intelligent selection of band-limiting baseband filters. In some implementations, the signals generated from the down conversion may be substantially estimated as:
In this case, the following control signals vi(t) and vq(t) may be used to substantially eliminate the leakage signal:
vi(t)=−c(t)·cos (t)
and
vq(t)=c(t)·sin (t).
A number of primary and secondary circuit and/or system impairments can limit performance of the reader 100. To indicate this difference, the baseband signals, i.e., the in-phase signal and the quadrature signal, into the dual ADC 126 are denoted as fi(t) and fq(t) as compared with ei(t) and eq(t).
The receiver module 104 passes or otherwise directs the baseband signals to the digital signal processor (DSP) 130. The DSP 130 can include any software, hardware, and/or firmware operable to process the residual signal. For example, the DSP 130 may generate control signals for adjusting the cancellation signal used to compensate for leakage signal. In some implementations, the DSP 130 compensates the baseband signals for DC offset and/or phase offset. As mentioned above, the reader 100 may include elements that subtract DC offsets and/or de-rotate phase offsets in the baseband signals. Otherwise, these offsets can reduce the efficacy of the cancellation signal in reducing the leakage signal. In other words, the DSP 130 may eliminate, minimize, or otherwise reduce the DC offset and/or the phase offset to reduce error in the cancellation signal. In the case of DC offset, the DSP 130 can, in some implementations, subtract estimates of the DC offsets in the baseband signals such as the in-phase signal and the quadrature signal. For example, the DSP 130 may determine samples (e.g., hundreds of samples) of the DC offset for the baseband signals and generate an average for each baseband signal based, at least in part, on the samples. In this example, the DSP 130 may subtract the DC offset from the corresponding baseband signal during steady state. In regards to the phase offset, the DSP 130 may introduce a phase shift in the baseband signals to minimize, eliminate, or otherwise reduce the phase shift generated by the elements in the reader 100. In some cases, varying a control value on one baseband signal (e.g., in-phase signal) can produce a change on the other baseband signal (e.g., quadrature signal). This cross-coupling between the two baseband signals can, in some implementations, lead to a more complex control algorithm for compensating for the phase shift offset.
The transmitter module 106 can include any software, hardware, and/or firmware operable to generate transmission signals for transponders. In the illustrated implementation, the transmitter module 106 includes a DAC 132, a LPF 134, a transmission mixer 136 and a power amplifier 138. The DAC 132 receives a digital signal from the DSP 130 and converts the digital signal to analog signals. For example, the digital signal can encode queries for transponders to identify associated information. The DAC 132 passes the analog signal to the LPF 134 to attenuate higher frequencies than a cutoff frequency from the analog signals. The LPF 134 passes the analog signals to the transmission mixer 136 to upconvert the baseband signals to an RF signals. In this case, the transmission mixer 136 receives a signal from the frequency synthesizer 128 and mixes this signal with the analog signal to generate the RF signal. The power amplifier 138 amplifies the RF signal and directs the amplified signal to the power splitter 108. In some implementations, the power splitter 108 may comprise a coupler.
Regarding the DC offsets, the loops 202 and 204 are effectively DC coupled loops and, as a result, DC offsets in the signal paths can directly effect the estimated control signals vi(t) and vq(t). Such DC offsets are represented in the model 200 as the DC offsets 206a and 206b. As discussed above, the DSP 130 eliminates, minimizes, or otherwise reduces these DC offsets from the loops 202 and 204. In the illustrated implementation, the DSP 130 includes a DC-offset-removal module 208 to subtract DC offsets from the in-phase signal and the quadrature signal. In addition, the module 208 may sample the baseband signals to estimate the DC offsets. For example, the module 208 may take hundreds of samples to determine average DC offsets to subtract from the baseband signals.
Regarding the phase-shift offsets, the elements in the reader 100 can impart a phase shift in the loops 202 and 204 and, as a result, this phase shift can directly effect the estimated control signals vi(t) and vq(t). For example, the phase shift can be due to quadrature modulator, summer, low noise amplifier, down conversion mixer, baseband filtering, and other elements. Such phase shifts in the loops 202 and 204 are represented in the model 200 as unknown phase shift 210. As discussed above, the DSP 130 eliminates, minimizes, or otherwise reduces these phase-shift offsets from the loops 202 and 204. In the illustrated implementation, the DSP 130 includes a phase rotation module 212 to de-rotate the in-phase signal and the quadrature signal by angle θ. In some implementations, the de-rotation is performed by a standard complex multiply of e−j0. In addition, the module 212 may sample the baseband signals to estimate the phase-shift offsets. For example, the module 212 may take hundreds of samples to determine an average phase shift for each signal and de-rotate each signal in accordance with the associated averages.
In addition, the DSP 130 includes gains 214a-b and integrators 216a-b. The gains 214a-b allow the tracking bandwidth of the leakage cancellation system to be adjusted. The gains 214a and 214b may generate a gain value on each loop 202 and 204. In some implementations, the gains 214a and 214b generate gain values in light of a desire for fast convergence and loop stability. Further, the gain value can be adjusted over time to be large at first for quick approximation and then later made smaller to improve accuracy in the final results. Lower gain values reduce the bandwidth of the leakage cancellation system and make the system less responsive to noise signals. The integrators 216a-b filter the error signals to produce accurate control outputs.
The leakage path is illustrated in the model as the transmitter leakage function 218. This function 218, shown as a single element, typically results from a number of leakage paths, one of which can be the circulator 140. These leakage paths combine to yield a composite transmitter leakage function 218. The leakage signal is often a sinusoid of some general amplitude and phase where each is generally a function of the transmit frequency. In some implementations, the leakage signal can be an unpopulated sinusoid, because the transmitter is frequently unpopulated during the receive mode of operation. Though, the concept could be applied successfully as well with a relatively slowly modulated transmit carrier being used during receive operations. As mentioned above, the leakage signal of interest could be viewed as a sinusoid of some amplitude and phase and can be expressed in polar form.
Regarding
Referring to
Referring to
A number of embodiments of the invention have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the invention.
This application claims priority under 35 USC §119(e) to U.S. Patent Application Ser. No. 60/795,625, filed on Apr. 27, 2006, the entire contents of which are hereby incorporated by reference.
Number | Name | Date | Kind |
---|---|---|---|
3568197 | Cubley | Mar 1971 | A |
3663932 | Mount et al. | May 1972 | A |
3688250 | Howlett | Aug 1972 | A |
3696429 | Tressa | Oct 1972 | A |
3876946 | La Clair et al. | Apr 1975 | A |
3984835 | Kaplan et al. | Oct 1976 | A |
4243955 | Daniel et al. | Jan 1981 | A |
4297672 | Fruchey et al. | Oct 1981 | A |
4325057 | Bishop | Apr 1982 | A |
4509123 | Vereen | Apr 1985 | A |
4595915 | Close | Jun 1986 | A |
4849706 | Davis et al. | Jul 1989 | A |
4857925 | Brubaker | Aug 1989 | A |
4870391 | Cooper | Sep 1989 | A |
4873529 | Gibson | Oct 1989 | A |
4903033 | Tsao et al. | Feb 1990 | A |
4968967 | Stove | Nov 1990 | A |
5012225 | Gill | Apr 1991 | A |
5021780 | Fabiano et al. | Jun 1991 | A |
5038283 | Caveney | Aug 1991 | A |
5095536 | Loper | Mar 1992 | A |
5165109 | Han et al. | Nov 1992 | A |
5278563 | Spiess | Jan 1994 | A |
5278569 | Ohta et al. | Jan 1994 | A |
5293408 | Takahashi et al. | Mar 1994 | A |
5334822 | Sanford | Aug 1994 | A |
5381157 | Shiga | Jan 1995 | A |
5396489 | Harrison | Mar 1995 | A |
5430441 | Bickley et al. | Jul 1995 | A |
5444864 | Smith | Aug 1995 | A |
5461374 | Lewiner et al. | Oct 1995 | A |
5477215 | Mandelbaum | Dec 1995 | A |
5495500 | Jovanovich et al. | Feb 1996 | A |
5506584 | Boles | Apr 1996 | A |
5519729 | Jurisch et al. | May 1996 | A |
5539394 | Cato et al. | Jul 1996 | A |
5608379 | Narlow et al. | Mar 1997 | A |
5613216 | Galler | Mar 1997 | A |
5630072 | Dobbins | May 1997 | A |
5648767 | O'Connor et al. | Jul 1997 | A |
5649295 | Shober et al. | Jul 1997 | A |
5661485 | Manuel | Aug 1997 | A |
5661494 | Bondyopadhyay | Aug 1997 | A |
5668558 | Hong | Sep 1997 | A |
5708423 | Ghaffari et al. | Jan 1998 | A |
5729576 | Stone et al. | Mar 1998 | A |
5745037 | Guthrie et al. | Apr 1998 | A |
5777561 | Chieu et al. | Jul 1998 | A |
5784414 | Bruekers et al. | Jul 1998 | A |
5825753 | Betts et al. | Oct 1998 | A |
5831578 | Lefevre | Nov 1998 | A |
5841814 | Cupo | Nov 1998 | A |
5850187 | Carrender et al. | Dec 1998 | A |
5861848 | Iwasaki | Jan 1999 | A |
5892396 | Anderson et al. | Apr 1999 | A |
5898405 | Iwasaki | Apr 1999 | A |
5905405 | Ishizawa | May 1999 | A |
5940006 | MacLellan et al. | Aug 1999 | A |
5974301 | Palmer et al. | Oct 1999 | A |
6025780 | Bowers et al. | Feb 2000 | A |
6026378 | Onozaki | Feb 2000 | A |
6084530 | Pidwerbetsky et al. | Jul 2000 | A |
6094149 | Wilson | Jul 2000 | A |
6107910 | Nysen | Aug 2000 | A |
6121929 | Olson et al. | Sep 2000 | A |
6137447 | Saitoh et al. | Oct 2000 | A |
6177861 | MacLellan et al. | Jan 2001 | B1 |
6192225 | Arpaia et al. | Feb 2001 | B1 |
6219534 | Torii | Apr 2001 | B1 |
6229817 | Fischer et al. | May 2001 | B1 |
6229987 | Greeff et al. | May 2001 | B1 |
6232837 | Yoo et al. | May 2001 | B1 |
6275192 | Kim | Aug 2001 | B1 |
6317027 | Watkins | Nov 2001 | B1 |
6320542 | Yamamoto et al. | Nov 2001 | B1 |
6366216 | Olesen | Apr 2002 | B1 |
6412086 | Friedman et al. | Jun 2002 | B1 |
6414626 | Greef et al. | Jul 2002 | B1 |
6442276 | Doljack | Aug 2002 | B1 |
6456668 | MacLellan et al. | Sep 2002 | B1 |
6459687 | Bourlas et al. | Oct 2002 | B1 |
6466130 | Van Horn et al. | Oct 2002 | B2 |
6492933 | McEwan | Dec 2002 | B1 |
6501807 | Chieu et al. | Dec 2002 | B1 |
6531957 | Nysen | Mar 2003 | B1 |
6538564 | Cole | Mar 2003 | B1 |
6566997 | Bradin | May 2003 | B1 |
6567648 | Ahn et al. | May 2003 | B1 |
6603391 | Greeff et al. | Aug 2003 | B1 |
6639509 | Martinez | Oct 2003 | B1 |
6686830 | Schirtzer | Feb 2004 | B1 |
6700547 | Mejia et al. | Mar 2004 | B2 |
6714121 | Moore | Mar 2004 | B1 |
6714133 | Hum et al. | Mar 2004 | B2 |
6768441 | Singvall et al. | Jul 2004 | B2 |
6774685 | O'Toole et al. | Aug 2004 | B2 |
6784789 | Eroglu et al. | Aug 2004 | B2 |
6794000 | Adams et al. | Sep 2004 | B2 |
6798384 | Aikawa et al. | Sep 2004 | B2 |
6816125 | Kuhns et al. | Nov 2004 | B2 |
6819938 | Sahota | Nov 2004 | B2 |
6831603 | Menache | Dec 2004 | B2 |
6838989 | Mays et al. | Jan 2005 | B1 |
6888509 | Atherton | May 2005 | B2 |
6974928 | Boom | Dec 2005 | B2 |
6996164 | Blount et al. | Feb 2006 | B1 |
7009496 | Arneson et al. | Mar 2006 | B2 |
7034689 | Teplitxky et al. | Apr 2006 | B2 |
7039359 | Martinez | May 2006 | B2 |
7043269 | Ono et al. | May 2006 | B2 |
7053755 | Atkins et al. | May 2006 | B2 |
7058368 | Nicholls et al. | Jun 2006 | B2 |
7084769 | Bauer et al. | Aug 2006 | B2 |
7088248 | Forster | Aug 2006 | B2 |
7091828 | Greeff et al. | Aug 2006 | B2 |
7095324 | Conwell et al. | Aug 2006 | B2 |
7095985 | Hofmann | Aug 2006 | B1 |
7099406 | Najarian et al. | Aug 2006 | B2 |
7099671 | Liang | Aug 2006 | B2 |
7100835 | Selker | Sep 2006 | B2 |
7109867 | Forster | Sep 2006 | B2 |
7155172 | Scott | Dec 2006 | B2 |
7180402 | Carrender et al. | Feb 2007 | B2 |
7197279 | Bellantoni | Mar 2007 | B2 |
7199713 | Barink et al. | Apr 2007 | B2 |
7215976 | Brideglall | May 2007 | B2 |
7221900 | Reade et al. | May 2007 | B2 |
7256682 | Sweeney, II | Aug 2007 | B2 |
7257079 | Bachrach | Aug 2007 | B1 |
7284703 | Powell et al. | Oct 2007 | B2 |
7357299 | Frerking | Apr 2008 | B2 |
7375634 | Sprague | May 2008 | B2 |
7385511 | Muchkaev | Jun 2008 | B2 |
7388468 | Diorio et al. | Jun 2008 | B2 |
7388501 | Tang et al. | Jun 2008 | B2 |
7409194 | Shi et al. | Aug 2008 | B2 |
7411505 | Smith et al. | Aug 2008 | B2 |
7413124 | Frank et al. | Aug 2008 | B2 |
7429953 | Buris et al. | Sep 2008 | B2 |
7432817 | Phipps et al. | Oct 2008 | B2 |
7432874 | Meissner | Oct 2008 | B2 |
7440743 | Hara et al. | Oct 2008 | B2 |
7450919 | Chen et al. | Nov 2008 | B1 |
7460014 | Pettus | Dec 2008 | B2 |
7477887 | Youn | Jan 2009 | B2 |
7479874 | Kim et al. | Jan 2009 | B2 |
7492812 | Ninomiya et al. | Feb 2009 | B2 |
7526266 | Al-Mahdawi | Apr 2009 | B2 |
7548153 | Gravelle et al. | Jun 2009 | B2 |
7551085 | Pempsell et al. | Jun 2009 | B2 |
7557762 | Shimasaki et al. | Jul 2009 | B2 |
7561866 | Oliver et al. | Jul 2009 | B2 |
7562083 | Smith et al. | Jul 2009 | B2 |
7570164 | Chakraborty et al. | Aug 2009 | B2 |
7576657 | Duron et al. | Aug 2009 | B2 |
7580378 | Carrender et al. | Aug 2009 | B2 |
7583179 | Wu et al. | Sep 2009 | B2 |
7586416 | Ariyoshi et al. | Sep 2009 | B2 |
7592898 | Ovard et al. | Sep 2009 | B1 |
7592915 | Liu | Sep 2009 | B2 |
7594153 | Kim et al. | Sep 2009 | B2 |
7595729 | Ku et al. | Sep 2009 | B2 |
7596189 | Yu et al. | Sep 2009 | B2 |
7606532 | Wuidart | Oct 2009 | B2 |
7609163 | Shafer | Oct 2009 | B2 |
7612675 | Miller et al. | Nov 2009 | B2 |
20010048715 | Lee et al. | Dec 2001 | A1 |
20020021208 | Nicholson et al. | Feb 2002 | A1 |
20020067264 | Soehnlen | Jun 2002 | A1 |
20020072344 | Souissi | Jun 2002 | A1 |
20020080728 | Sugar et al. | Jun 2002 | A1 |
20020119748 | Prax et al. | Aug 2002 | A1 |
20020141347 | Harp et al. | Oct 2002 | A1 |
20030021367 | Smith | Jan 2003 | A1 |
20030052161 | Rakers et al. | Mar 2003 | A1 |
20030228860 | Jou | Dec 2003 | A1 |
20050084003 | Duron et al. | Apr 2005 | A1 |
20050099270 | Diorio et al. | May 2005 | A1 |
20050099340 | Suzuki | May 2005 | A1 |
20050107051 | Aparin et al. | May 2005 | A1 |
20050114326 | Smith et al. | May 2005 | A1 |
20050116867 | Park et al. | Jun 2005 | A1 |
20050156031 | Goel et al. | Jul 2005 | A1 |
20050179520 | Ziebertz | Aug 2005 | A1 |
20050207509 | Saunders et al. | Sep 2005 | A1 |
20050237843 | Hyde | Oct 2005 | A1 |
20050259768 | Yang et al. | Nov 2005 | A1 |
20060022800 | Krishna et al. | Feb 2006 | A1 |
20060033607 | Bellantoni | Feb 2006 | A1 |
20060086809 | Shanks et al. | Apr 2006 | A1 |
20060098765 | Thomas et al. | May 2006 | A1 |
20060103533 | Pahlavan et al. | May 2006 | A1 |
20060125603 | Nahear | Jun 2006 | A1 |
20060132313 | Moskowitz | Jun 2006 | A1 |
20060183454 | Al-Mahdawi | Aug 2006 | A1 |
20060214773 | Wagner et al. | Sep 2006 | A1 |
20060238302 | Loving et al. | Oct 2006 | A1 |
20060252398 | Park et al. | Nov 2006 | A1 |
20060267734 | Taki et al. | Nov 2006 | A1 |
20060290502 | Rawlings | Dec 2006 | A1 |
20070001809 | Kodukula et al. | Jan 2007 | A1 |
20070001813 | Maguire et al. | Jan 2007 | A1 |
20070018792 | Take et al. | Jan 2007 | A1 |
20070046432 | Aiouaz et al. | Mar 2007 | A1 |
20070060075 | Mikuteit | Mar 2007 | A1 |
20070082617 | McCallister | Apr 2007 | A1 |
20070133392 | Shin et al. | Jun 2007 | A1 |
20070139200 | Yushkov et al. | Jun 2007 | A1 |
20070164868 | Deavours et al. | Jul 2007 | A1 |
20070188305 | Drucker | Aug 2007 | A1 |
20070206704 | Zhou et al. | Sep 2007 | A1 |
20070206705 | Stewart | Sep 2007 | A1 |
20070222604 | Phipps et al. | Sep 2007 | A1 |
20070222606 | Phipps et al. | Sep 2007 | A1 |
20070236335 | Aiouaz et al. | Oct 2007 | A1 |
20070285238 | Batra | Dec 2007 | A1 |
20070290846 | Schilling et al. | Dec 2007 | A1 |
20080012688 | Ha et al. | Jan 2008 | A1 |
20080018431 | Turner et al. | Jan 2008 | A1 |
20080048867 | Oliver et al. | Feb 2008 | A1 |
20080049870 | Shoarinejad et al. | Feb 2008 | A1 |
20080065957 | Shoarinejad et al. | Mar 2008 | A1 |
20080068173 | Alexis et al. | Mar 2008 | A1 |
20080084310 | Nikitin et al. | Apr 2008 | A1 |
20080136595 | Finkenzeller | Jun 2008 | A1 |
20080143486 | Downie et al. | Jun 2008 | A1 |
20080191961 | Tuttle | Aug 2008 | A1 |
20080258916 | Diorio et al. | Oct 2008 | A1 |
20080278286 | Takaluoma et al. | Nov 2008 | A1 |
20090022067 | Gotwals | Jan 2009 | A1 |
20090053996 | Enguent et al. | Feb 2009 | A1 |
20090091454 | Tuttle | Apr 2009 | A1 |
20090096612 | Seppa et al. | Apr 2009 | A1 |
20090101720 | Dewan et al. | Apr 2009 | A1 |
Number | Date | Country |
---|---|---|
2218269 | Apr 1999 | CA |
0133317 | Feb 1985 | EP |
0498369 | Aug 1992 | EP |
0156440 | Dec 1992 | EP |
0915573 | May 1999 | EP |
0923061 | Jun 1999 | EP |
1095427 | May 2001 | EP |
1436857 | Jul 2004 | EP |
2648602 | Dec 1990 | FR |
1270456 | Apr 1972 | GB |
1158836 | Jun 1989 | JP |
2002-185381 | Jun 2002 | JP |
2005-227818 | Aug 2005 | JP |
2005-253058 | Sep 2005 | JP |
2006-252367 | Sep 2006 | JP |
2002-0091572 | Dec 2002 | KR |
WO 9016119 | Dec 1990 | WO |
WO 9615596 | May 1996 | WO |
WO 9905659 | Feb 1999 | WO |
WO 0021204 | Apr 2000 | WO |
WO 0124407 | Apr 2001 | WO |
WO 03044892 | May 2003 | WO |
WO 04001445 | Dec 2003 | WO |
WO 2005072137 | Aug 2005 | WO |
WO 2005109500 | Nov 2005 | WO |
WO 2006037241 | Apr 2006 | WO |
WO 2006068635 | Jun 2006 | WO |
WO 2007003300 | Jan 2007 | WO |
WO 2007094787 | Aug 2007 | WO |
WO 2007126240 | Nov 2007 | WO |
WO 2009058809 | May 2009 | WO |
Number | Date | Country | |
---|---|---|---|
20080041953 A1 | Feb 2008 | US |
Number | Date | Country | |
---|---|---|---|
60795625 | Apr 2006 | US |