1. A far field radio frequency identification (RFID) reader comprises:
a baseband processing module coupled to:
convert outbound data into outbound modulation information; and
convert an inbound baseband signal into inbound data;
a transmitter section that includes:
an oscillation module coupled to generate a radio frequency (RF) oscillation; and
a power amplifier module coupled to amplify and to modulate the RF oscillation based on the modulation information to produce an outbound RF signal; and
a receiver section that includes:
a low noise amplifier module coupled to amplify an inbound RF signal to produce an amplified inbound RF signal;
a down conversion module coupled to convert the amplified inbound RF signal into the inbound baseband signal; and
a current mode blocking circuit coupled to substantially compensate for a blocking current component of the baseband inbound signal and to pass, substantially unattenuated, a desired signal current component of the baseband inbound signal.
2. The far field RFID reader of claim 1, wherein the low noise amplifier module comprises:
a transconductance low noise amplifier coupled to amplify the inbound RF signal to produce an inbound RF current, wherein the down conversion module converts the inbound RF current signal into an inbound baseband current signal, wherein the inbound baseband current signal includes the blocking current component and the desired signal current component.
3. The far field RFID reader of claim 1, wherein the down conversion module comprises:
a mixing module coupled to mix the amplified inbound RF signal with the RF oscillation or with a receiver local oscillation to produce a mixed signal;
a filtering module coupled to filter the mixed signal to produce the inbound baseband signal; and
a transconductance stage coupled to convert the inbound baseband signal into an inbound baseband current signal that includes the blocking current component and the desired signal current component.
4. The far field RFID reader of claim 1 further comprises:
an adjustable attenuation module coupled to attenuate the outbound RF signal to produce an attenuated outbound RF signal, wherein the low noise amplifier module receives the attenuated outbound RF signal.
5. The far field RFID reader of claim 1, wherein the current mode blocking circuit comprises:
a controlled current source that generates a reference current corresponding to the blocking current component; and
an impedance coupled in series with the controlled current source to produce a series circuit, wherein a common node of the series circuit receives a current representation of the inbound baseband signal, and wherein a voltage across the impedance represents a desired baseband signal.
6. The far field RFID reader of claim 5, wherein the baseband processing module further functions to:
determines a blocking current setting based on the outbound RF signal; and
provides the blocking current setting to the controlled current source such that the controlled current source generates the reference current corresponding to the blocking current component.
7. The far field RFID reader of claim 1, wherein the power amplifier module comprises:
a power amplifier coupled to amplify and to modulate the RF oscillation in accordance with the outbound modulation information to produce an amplified and modulated RF signal; and
a transformer coupled to electromagnetically produce the outbound RF signal from the amplified and modulated RF signal.
8. A far field radio frequency identification (RFID) reader comprises:
a baseband processing module coupled to:
convert outbound data into outbound modulation information; and
convert an inbound baseband signal into inbound data;
a transmitter section that includes:
an oscillation module coupled to generate a radio frequency (RF) oscillation; and
a power amplifier module coupled to amplify and to modulate the RF oscillation based on the modulation information to produce an outbound RF signal; and
a receiver section that includes:
a low noise amplifier module coupled to amplify an inbound RF signal to produce an amplified inbound RF signal;
a limiting module coupled to limit the inbound RF signal to produce a limited inbound RF signal;
a first down conversion module coupled to convert the amplified inbound RF signal into the inbound baseband signal;
a second down conversion module coupled to convert the limited inbound RF signal into a limited inbound baseband signal; and
a current mode blocking circuit coupled to substantially compensate for a blocking current component of the baseband inbound signal and to pass, substantially unattenuated, a desired signal current component of the baseband inbound signal based on a current representation of the limited inbound baseband signal.
9. The far field RFID reader of claim 8, wherein the current mode blocking circuit comprises:
a first current source that generates a reference current;
a first impedance coupled in series with the first current source to produce a first series circuit, wherein a first common node of the first series circuit receives a current representation of the inbound baseband signal;
a second current source that generates the reference current;
a second impedance coupled in series with the second controlled current source to produce a second series circuit, wherein a second common node of the second series circuit receives the current representation of the limited inbound baseband signal, wherein a different between the first common node and the second common node represents a desired baseband signal.
10. The far field RFID reader of claim 9, wherein the current mode blocking circuit further comprises:
an amplifier having a first input, a second input, and an output, wherein the first input is coupled to the first common node and the second input is coupled to the second common node, where the output provides a desired voltage signal.
11. The far field RFID reader of claim 8 further comprises:
the low noise amplifier module including a transconductance low noise amplifier coupled to amplify the inbound RF signal to produce an inbound RF current, wherein the first down conversion module converts the inbound RF current signal into an inbound baseband current signal, wherein the inbound baseband current signal includes the blocking current component and the desired signal current component; and
the limiting module including a limiter and a transconductance stage, wherein the limiter limits the inbound RF signal to produce a limited RF signal and the transconductance stage produces the limited inbound RF signal in a current mode from the limited RF signal to produce a limited inbound RF current signal, wherein the second down conversion module converts the limited inbound RF current signal into the a current representation of the limited inbound baseband signal.
12. The far field RFID reader of claim 8 further comprises:
the first down conversion module including:
a first mixing module coupled to mix the amplified inbound RF signal with the RF oscillation or with a receiver local oscillation to produce a first mixed signal;
a first filtering module coupled to filter the first mixed signal to produce the inbound baseband signal; and
a first transconductance stage coupled to convert the inbound baseband signal into an inbound baseband current signal that includes the blocking current component and the desired signal current component; and
the second down conversion module including:
a second mixing module coupled to mix the limited inbound RF signal with the RF oscillation or with the receiver local oscillation to produce a second mixed signal;
a second filtering module coupled to filter the second mixed signal to produce the limited inbound baseband signal; and
a first transconductance stage coupled to convert the limited inbound baseband signal into the current representation of the limited inbound baseband signal.
13. The far field RFID reader of claim 8 further comprises:
an adjustable attenuation module coupled to attenuate the outbound RF signal to produce an attenuated outbound RF signal, wherein the low noise amplifier module and the limiting module receive the attenuated outbound RF signal.
14. A far field radio frequency identification (RFID) reader comprises:
a baseband processing module coupled to:
convert outbound data into outbound modulation information; and
convert an inbound baseband signal into inbound data;
a transmitter section that includes:
an oscillation module coupled to generate a radio frequency (RF) oscillation; and
a power amplifier module coupled to amplify and to modulate the RF oscillation based on the modulation information to produce an outbound RF signal; and
a receiver section that includes:
a transconductance low noise amplifier module coupled to amplify an inbound RF signal to produce an amplified inbound RF current signal;
a current mode blocking circuit coupled to substantially compensate for a blocking current component of the amplified inbound RF current signal and to pass, substantially unattenuated, a signal current component of the amplified inbound RF current signal; and
a down conversion module coupled to convert the signal current component into the desired inbound signal.
15. The far field RFID reader of claim 14, wherein the current mode blocking circuit comprises:
a controlled digital to analog converter that generates a reference current corresponding to the blocking current component; and
a load coupled in series with the controlled digital to analog converter to produce a series circuit, wherein a common node of the series circuit receives the amplified inbound RF current signal, and wherein a current through the load represents a desired RF current signal.
16. The far field RFID reader of claim 15, wherein the baseband processing module further functions to:
generates a sinusoidal blocking signal based on the outbound RF signal; and
provides the sinusoidal blocking signal to the controlled digital to analog converter such that the controlled digital to analog converter generates the reference current corresponding to the blocking current component.
17. The far field RFID reader of claim 14, wherein the power amplifier module comprises:
a power amplifier coupled to amplify and to modulate the RF oscillation in accordance with the outbound modulation information to produce an amplified and modulated RF signal; and
a transformer coupled to electromagnetically produce the outbound RF signal from the amplified and modulated RF signal.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
What is claimed is:
1. A filter element comprising:
(a) a media construction comprising a corrugated sheet secured to a flat sheet rolled into a coiled construction; the coiled construction defining a plurality of flutes, a first end, an opposite second end, and an outer annular surface;
(i) said plurality of flutes comprising inlet flutes and outlet flutes;
(A) said inlet flutes being open at portions adjacent to said first end and closed at portions adjacent to said second end; and said outlet flutes being closed at portions adjacent to said first end and open at portions adjacent to said second end; and
(b) a mounting flange secured to said coiled construction; said mounting flange projecting radially from said outer, annular surface of said coiled construction;
(i) said mounting flange defining at least one fastener socket to axially mount the filter element into a housing.
2. A filter element according to claim 1 wherein:
(a) said mounting flange defines first and second opposite axial surfaces; said first axial surface being a sealing surface to receive a bellows for directing gas into said first end of said coiled construction.
3. A filter element according to claim 2 wherein:
(a) said mounting flange further includes a guiding surface to orient a bellows; said guiding surface comprising an arc having a concave surface extending from said first axial surface to said coiled construction.
4. A filter element according to claim 3 further including:
(a) a grid construction secured to said coiled construction; said grid construction including a screen oriented over said coiled construction first end;
(i) said mounting flange and said grid construction are an integral, unitary piece.
5. A filter element according to claim 4 wherein:
(a) said grid construction includes a band supporting said screen;
(i) said band circumscribing and being secured to said outer, annular surface of said coiled construction.
6. A filter element according to claim 5 wherein:
(a) said grid construction further includes an outer wall spaced from and circumscribing said band;
(i) said outer wall and said band defining a channel therebetween;
(ii) said outer wall defining a plurality of spaced voids therein.
7. A filter element according to claim 6 wherein:
(a) said mounting flange extends from said grid construction outer wall.
8. A filter element according to claim 7 further including:
(a) a ramp construction extending from said arc to said screen.
9. A filter element according to claim 4 wherein:
(a) said screen includes a plurality of spokes extending from a central hub and a plurality of arched members extending between said spokes.
10. A filter element according to claim 4 further including:
(a) a seal member oriented adjacent to said second end of said coiled construction; and
(b) a frame having a skirt and an axial extension;
(i) said skirt circumscribing and securing said frame to said coiled construction;
(ii) said axial extension having an annular portion;
(A) said annular portion of said axial extension supporting said seal member.
11. A filter element according to claim 1 further including:
(a) a grid construction secured to said coiled construction; said grid construction including a screen oriented over said coiled construction first end; a tubular band supporting said screen; and an outer wall spaced from and circumscribing said band;
(i) said screen including a plurality of spokes extending from a central hub and a plurality of arched members extending between said spokes;
(ii) said tubular band circumscribing and being secured to said outer, annular surface of said coiled construction;
(iii) said outer wall and said band defining a housing engagement pocket therebetween; and
(iv) said outer wall defining a plurality of spaced voids therein.
12. An air cleaner comprising:
(a) a housing defining an interior volume;
(b) a filter element operably oriented at least partially in said housing interior volume; said filter element comprising:
(i) a media construction comprising a corrugated sheet secured to a flat sheet rolled into a coiled construction; the coiled construction defining a plurality of flutes, a first end, an opposite second end, and an outer annular surface;
(A) said plurality of flutes comprising inlet flutes and outlet flutes; said inlet flutes being open at portions adjacent to said first end and closed at portions adjacent to said second end; and said outlet flutes being closed at portions adjacent to said first end and open at portions adjacent to said second end; and
(ii) a mounting flange secured to said coiled construction; said mounting flange projecting radially from said outer, annular surface of said coiled construction;
(A) said mounting flange defining a plurality of fastener-receiving sockets axially therethrough; and
(c) a plurality of fasteners extending through said fastener-receiving sockets of said mounting flange to secure said filter element to said housing.
13. An air cleaner according to claim 12 further including:
(a) a radial seal oriented between said filter element and said housing.
14. An air cleaner according to claim 13 wherein:
(a) said mounting flange defines first and second opposite axial surfaces; said first axial surface being a sealing surface to receive a bellows for directing gas into said first end of said coiled construction; and
(b) said mounting flange further includes a guiding surface to orient the bellows; said guiding surface comprising an arc having a concave surface extending from said first axial surface to said coiled construction.
15. An air cleaner according to claim 14 wherein:
(a) said housing includes a sidewall and plurality of fastener housings mounted on said sidewall;
(i) said fastener housings receiving said plurality of fasteners to secure said filter element to said housing; and
(b) said filter element further includes a grid construction secured to said coiled construction; said grid construction including a screen oriented over said coiled construction first end; a tubular band supporting said screen; and an outer wall spaced from and circumscribing said band;
(i) said tubular band circumscribing and being secured to said outer, annular surface of said coiled construction;
(ii) said outer wall and said band defining a housing engagement pocket therebetween;
(A) said housing sidewall being oriented within said housing engagement pocket; and
(iii) said outer wall defining a plurality of spaced voids therein oriented adjacent to said fastener housings.
16. An air cleaner according to claim 14 further comprising:
(a) a bellows oriented over said coiled construction first end; said bellows having an end in engagement with said sealing surface of said mounting flange.
17. A method of installing a filter element in an air cleaner housing; the method comprising:
(a) providing a filter element comprising:
(i) a media construction comprising a corrugated sheet secured to a flat sheet rolled into a coiled construction; the coiled construction defining a plurality of flutes, a first end, an opposite second end, and an outer annular surface;
(A) the plurality of flutes comprising inlet flutes and outlet flutes; the inlet flutes being open at portions adjacent to the first end and closed at portions adjacent to the second end; and the outlet flutes being closed at portions adjacent to the first end and open at portions adjacent to the second end;
(ii) a mounting flange secured to the coiled construction; the mounting flange projecting radially from the outer, annular surface of the coiled construction and adjacent to the first end of the coiled construction;
(b) orienting the filter element into an interior volume of a housing;
(c) forming a radial seal between the filter element and the housing adjacent to the second end of the coiled construction; and
(d) securing the filter element to the housing by axial engagement between the mounting flange and the housing.
18. A method according to claim 17 wherein:
(a) said step of providing a filter element includes providing a filter element having a grid construction secured to the coiled construction; the grid construction including a screen oriented over the coiled construction first end; a tubular band supporting the screen; and an outer wall spaced from and circumscribing the band;
(i) the screen including a plurality of spokes extending from a central hub and a plurality of arched members extending between the spokes;
(ii) the tubular band circumscribing and being secured to the outer, annular surface of the coiled construction;
(b) said step of orienting the filter element into an interior volume of a housing including engaging a sidewall of the housing in a pocket between the outer wall and the band; and
(c) said step of securing the filter element to the housing includes inserting a plurality of bolts through sockets in the mounting flange and into receiving sockets in said housing.
19. A method according to claim 18 further including:
(a) after said step of securing the filter element to the housing, guiding a bellows over the first end of the coiled construction using a contoured surface of the mounting flange.