WO2009046228A1

WO2009046228A1 - Multiplexed multi-band signal amplification

Info

Publication number: WO2009046228A1
Application number: PCT/US2008/078637
Authority: WO
Inventors: Timothy R. Geis
Original assignee: Intelligent Wireless Products, Inc.
Priority date: 2007-10-02
Filing date: 2008-10-02
Publication date: 2009-04-09

Abstract

The invention includes an apparatus and a method of amplifying a multi-band signal. The apparatus includes diplexer circuits, an amplifier circuit, and filter circuits. One diplexer circuit is arranged to split a multi-band input signal into multiple single-band signals for separate filtration. Another diplexer is arranged to combine the multiple filtered single-band signals into a single multi-band signal for combined amplification. A third diplexer circuit is arranged to split the amplified multi-band signal into multiple single-band output signals. Also, separate or combined gain control circuits may be included. Multiple amplification circuits, filtration circuits, and gain control circuits may be included in an apparatus, which may be applied to signals for unidirectional and/or bidirectional communication.

Description

Docket No.: 2207746-WOO

MULTIPLEXED MULTI-BAND SIGNAL AMPLIFICATION

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of the earlier filing date of U.S. Provisional Application, titled "MULTIPLEXED MULTI-BAND SIGNAL AMPLIFICATION," Serial No. 60/977,058, filed on October 2, 2007, under 35 U.S.C. § 119(e), the contents of which are incorporated herein by reference in their entirety.

TECHNICAL FIELD

The present invention is generally directed to the area of signal amplification, and particularly, but not exclusively, to signal amplification in wireless communication systems.

BACKGROUND

Signal amplification is often employed to increase the gain, power, signal-to-noise ratio, and/or the like, of a signal. In certain systems, a multi-band signal may be employed to transmit data for one or more applications. For example, multiple frequency bands (e.g., bands in the 800 MHz, 1800MHz, and 1900 MHz range) are allocated for mobile telephony. Thus, mobile telephones and mobile telephone systems may include multi-band functionality and multi-band signal amplifiers.

In other systems, multiple data streams may also be modulated into a single multi- band signal. For example, digital-subscriber-line (DSL) signals are composed of a first data stream (e.g., voice) that is transmitted in a first frequency band and a second data stream (e.g,, digital data) that is transmitted in a second frequency band. In yet another example, AM/FM radio receivers receive amplitude modulated radio signals from one frequency band and receive frequency modulated radio signals from another frequency band.

IN THESE AND OTHER SYSTEMS, SEPARATE AMPLIFICATION CIRCUITRY AND SIGNAL PATHS ARE OFTEN EMPLOYED TO SEPARATELY AMPLIFY EACH SIGNAL COMPONENT IN EACH FREQUENCY BAND. HOWEVER, SEPARATE AMPLIFICATION OF EACH FREQUENCY BAND MAY INCREASE COMPONENT COUNT, CIRCUIT COMPLEXITY, AND/OR THE LIKE.

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EMBODIMENTS OF THIS INVENTION ARE DIRECTED TO THESE AND OTHER ASPECTS.

BRIEF DESCRIPTION OF THE DRAWINGS

Non- limiting and non-exhaustive embodiments of the present invention are described with reference to the following drawings. In the drawings, like reference numerals refer to like parts throughout the various figures unless otherwise specified. These drawings are not necessarily drawn to scale.

For a better understanding of the present invention, reference will be made to the following Detailed Description, which is to be read in association with the accompanying drawings, wherein:

FIGURE 1 is a block diagram of an embodiment of a unidirectional circuit according to aspects of the present invention; and

FIGURE 2 is a block diagram of another embodiment of a bidirectional circuit according to aspects of the present invention.

DETAILED DESCRIPTION

Various embodiments of the present invention will be described in detail with reference to the drawings. Reference to various embodiments does not limit the scope of the invention, which is limited only by the scope of the claims attached hereto. Additionally, any examples set forth in this specification are not intended to be limiting and merely set forth some of the many possible embodiments for the claimed invention.

Throughout the specification and claims, the following terms take at least the meanings explicitly associated herein, unless the context dictates otherwise. The meanings identified below do not necessarily limit the terms, but merely provide illustrative examples for the terms. The meaning of "a," "an," and "the" includes plural reference. References in the singular are made merely for clarity of reading and include plural reference unless plural reference is specifically excluded. The meaning of either "in" or "on" includes both "in" and "on." The term "or" is an inclusive "or" operator, and is equivalent to the term "and/or" unless specifically indicated otherwise. The term "based on" or "based upon" is not

3366213 1 9609309-000 Docket No.: 2207746-WOO exclusive and is equivalent to the term "based, at least in part on," and includes being based on additional factors, some of which are not described herein. The term "coupled" means at least either a direct electrical connection between the items connected, or an indirect connection through one or more passive or active intermediary devices. The term "circuit" means at least either a single component or a multiplicity of components, either active and/or passive, that are coupled together to provide a desired function or functions.

The term "signal" means at least one current, voltage, electromagnetic, optical, charge, temperature, data, or other signal and may include one or more data stream(s). The term "band" means a range of frequencies in the electromagnetic spectrum. A band may be in the radio frequency spectrum, microwave frequency spectrum, infrared spectrum, visible light spectrum, X-ray spectrum, gamma ray spectrum, and/or the like. The term "signal component" means a portion of a signal which includes a data stream. A signal component may be part of a multi-band or signal-band signal. The term "multi-band signal" means a signal that is employed to communicate signal components from more than one band. A multi-band signal may include signal components from two bands, three bands, and/or more bands. The term "single-band signal" means a signal that is employed to communicate signal components from less bands than the multi-band signal from which it is derived, or into which it is combined. The term "signal path" means the path through which a data stream travels. A signal path may travel through active or passive elements, along a signal, as a signal component along a signal, and/or the like. A "signal" may be used to communicate using frequency modulation, amplitude modulation, phase modulation, active high, active low, time multiplexed, synchronous, asynchronous, differential, single-ended, or any other analog or digital signaling or modulation techniques. The phrase "in one embodiment," as used herein does not necessarily refer to the same embodiment, although it may.

Briefly stated, the invention includes an apparatus and a method of amplifying a multi-band signal. Embodiments of this invention include apparatuses and methods of sharing amplification circuitry in multi-band systems. An embodiment of an apparatus includes multiplexer circuits, an amplifier circuit, and filter circuits. One diplexer circuit is arranged to split a multi-band input signal into multiple single-band signals for separate filtration. Another diplexer is arranged to combine the multiple filtered single-band signals into a single multi-band signal for combined amplification. Multi-band amplification is generally counter-intuitive, because combining bands generally increases the voltage, which

3366213 1 9609309-000 Docket No.: 2207746-WOO may cause the combined signal to swing into the non-linear range. However, embodiments of the present invention produce a combined signal to remain within the dynamic range of an amplifier. A third diplexer circuit is arranged to split the amplified multi-band signal into multiple single -band output signals. Also, separate or combined gain control circuits may be included. Multiple amplification circuits, filtration circuits, and gain control circuits may be included in an apparatus embodiment, which may be applied to signals for unidirectional and/or bidirectional communication. One example embodiment amplifies multiple bands for wireless communication.

FIGURE 1 is a block diagram of an embodiment of a unidirectional circuit 100, according to aspects of the present invention. Circuit 100 is a signal amplifier that is arranged to amplify multi-band input signal IN, and to provide single-band output signals OUTA and OUTB. In one embodiment, multi-band input signal IN includes signal components from two bands (BANDA and BANDB). In one example, BANDA may correspond to a cellular band signal component (800MHz), sometimes referred to as advanced mobile phone system (AMPS) band. BANDB may correspond to Personal Communications Services (PCS) band signal components (1800/1900 MHz). Those of ordinary skill will recognize that any signal, or combination of signals, may be provided as input signal IN.

In the illustrated embodiment, BANDA and BANDB signal paths employ shared circuitry. For example, this shared circuitry may reduce the size, power consumption, complexity, and/or the like, of circuit 100. Also, the BANDA and BANDB signal components may be in any frequency band of the electromagnetic spectrum. For example, they may be in the RF spectrum, microwave spectrum, audible spectrum, and/or the like.

In the illustrated embodiment diplexer DIPLl is arranged to receive multi-band input signal IN. As output, DIPLl provides the BANDA signal component of signal IN to filter FLTR A l via signal SlA, and provides the BANDB signal component of signal IN to filter FLTR B l via signal SlB. Diplexer DIPLl may be any multiplexor circuit that is suitable for splitting input signal IN into its constituent BANDA and BANDB signal components. For example, a multiplexor circuit may include a high-pass filter and a low-pass filter; two or more band-pass filters; and/or the like.

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Signal SlA is then filtered by filter FLTR A l to provide signal S2A. For example, filter FLTR A l may include a surface acoustic wave (SAW) filter. In other embodiments, other filters may be employed. For example, passive filters, active filters, analog filters, digital filters, and/or the like, may be suitably employed. These filters may include crystal filters, bulk acoustic wave filters, high-pass filters, low-pass filters, band-bass filters, RC filters, LC filters, RLC filters, and/or the like.

Likewise, signal SlB is filtered by filter FLTR B l provide signal S2B. After respective filtration of signals SlA and SlB, signals S2A and S2B are combined by diplexer DIPL2 to provide signal S3 to amplifier AMPl . Diplexer DIPL2 may be any multiplexor circuit that is suitable to combine two input signals into a signal output signal.

Signal S3 is then amplified by amplifier AMPl to provide signal S4. For example, amplifier AMPl may be a radio frequency (RF) amplifier, an operational amplifier circuit, a signal amplifier circuit, and/or the like. In one embodiment, amplifier AMPl is selected such that it has a relatively large dynamic range and is capable of amplifying both the BANDA and BANDB signal components of signal S3 without substantial clipping or saturation.

Amplifier AMPl may also receive a static, or dynamically determined gain control signal, to control amplification of signal S3.

After amplification by amplifier AMPl, signal S4 is split by diplexer DIPL3. Diplexer provides the BANDA signal component of signal S4 on signal S5 A to filter FLTR A 2 and provides the BANDB signal component of signal S4 on signal S5A to filter FLTR B 2. Filters FLTR A 2 and FLTR B 2 are respectively arranged to provide output signals OUTA and OUTB.

Although FIGURE 1 illustrates circuitry for amplifying a dual-band signal, other embodiments may include additional circuitry for amplifying multi-band input signal having signal components from three or more bands. These variations are within the spirit and scope of the invention.

In one embodiment, diplexers DIPL1-DIPL3, filters FLTR A l, FLTR A 2, FLTR B l, FLTR B 2, and amplifier AMPl are embodied on a monolithic integrated circuit. In another embodiment, they are discrete components mounted on one or more circuit boards. The circuit board(s) may be FR4, Polymide, PTFE, Phenolic, and/or the like,

3366213 1 9609309-000 Docket No.: 2207746-WOO and may be of laminate or non-laminate construction, and may have any number of layers. In at least one embodiment, components are mounted on a flexible circuit board made of Pyralux, RigidFlex, and/or the like. Also, if multiple circuit boards are employed, the boards may be connected by ribbon cables, thru-board connectors, board-edge connector, and/or the like. In one embodiment, multiple circuit boards, flexible circuits, and/or connectors may be stacked, coupled at angles or otherwise configured to reduce overall size, to fit into another assembly, to fit around existing parts, and/or to otherwise integrate into a desired packaging arrangement. One such embodiment may be a small integrated package in a vehicle. These variations are within the spirit and scope of the invention.

FIGURE 2 is a block diagram of an embodiment of a bidirectional circuit 200, according to aspects of the present invention. In one embodiment, circuit 200 is arranged to provide signal amplification in a wireless bi-directional communication system such as a mobile telephone system. For example, circuit 200 may be employed as a signal amplifier for increasing the gain of cellular band signal components (800MHz) and Personal Communications Services (PCS) band signal components (1800/1900 MHz) in a multi-band signal. Signal components in these bands may include a Global System for Mobile communication (GSM) data stream(s), General Packet Radio Services (GPRS) data stream(s), Enhanced Data GSM Environment (EDGE) data stream(s), Wideband Code Division Multiple Access (WCDMA) data stream(s), Universal Mobile Telephone System (UMTS) data stream(s), and/or the like. In one embodiment, circuit 200 may also be employed as a wireless-to-wireless signal amplifier. In another embodiment, circuit 200 may be employed to amplify a wireless signal that includes data stream such as an EDGE data stream. This EDGE data stream may, for example, be employed to enable communications between a local area network, such as an IEEE 802.11 network, and a wide area network, such as the Internet. However, other embodiments of circuit 200 may be arranged to amplify virtually any multi-band signal.

In one embodiment, circuit 200 is arranged to amplify four signal components. For example, for a mobile telephony system, these signal components may include:

BANDA Uplink PCS 1850 - 1910 MHz; BANDA Downlink PCS 1930 - 1990 MHz;

BANDB Uplink Cellular 0824 - 0849 MHz; and

BANDB Downlink Cellular 0869 - 0894 MHz.

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To reduce circuitry employed to amplify the four signal components, the BANDA uplink and BANDB uplink share amplification circuitry. Likewise, the BANDA downlink and the BANDB downlink also share amplification circuitry.

Illustrative Uplink Signal Path

In one embodiment, starting from input/output 101, the BANDA and BANDB signal components of signal UP are first split by diplexer DIPLl onto separate signals. At this point, diplexer DIPLl output signals are bidirectional and include both uplink and downlink signal components. BANDA uplink duplexer DUPLl then separates the BANDA downlink and uplink signals components onto separate signals. Duplexer DUPLl may be any multiplexor circuit that is suitable for separating the BANDA downlink and uplink signals components. For example, duplexer DUPLl may include a high-pass filter and a low-pass filter; two or more band-pass filters; and/or the like.

The BANDA uplink signal then goes to attenuator ATNl which selectively controls the signal strength to the following stages based, at least in part, on a signal strength detected by sensor SNSl. In one embodiment, the gain provided by circuit 200 is as described in a U.S. Patent Application to T. Geis, et al, with attorney docket number 21165/0207891 -USO, and entitled "Wireless to Wireless Signal Amplification With Gain Optimization and Oscillation Prevention," the entire contents of which are hereby incorporated by reference.

From attenuator ATNl the signal goes to filter FLl . In one embodiment, filter FLl includes a first 2 dB PAD, a SAW filter, and a second 2 dB PAD. For example, the SAW filter may be used to define a pass-band for the signal, and the PADs may be employed for providing relatively low attenuation impedance matching. In other embodiments, other filters, such as those discussed above, may be employed.

Likewise, the BANDB uplink signal goes through similar signal path, including duplexer DUPL2, attenuator ATN2, and filter FL2. However, in other embodiments, the BANDB uplink signal path may be different from the BANDA uplink signal path.

The BANDA and BANDB uplink signal paths are then combined by diplexer DIPL2. After diplexer DIPL2, the BANDA and BANDB uplink signal components are provided as a signal multi-band signal to amplifier AMPl . In one embodiment, amplifier AMPl is

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3366213 1 9609309-000 Docket No.: 2207746-WOO arranged to amplify the signal by approximately 20 dB. In one embodiment, amplifier AMPl is a LEE-59 amplifier, available from Mini-Circuits, Inc of Brooklyn, New York. However, other amplifiers, such as other RF amplifiers, operational amplifier circuits, power amplifiers, and/or the like, may also be suitably employed. The output of amplifier AMPl is then split by diplexer DIPL3 such that the BANDA signal component is provided to filter FL3, and the BANDB signal component is provided to filter FL4.

While the BANDA and BANDB signal components remain separate, the BANDA signal component passes through combination attenuator amplifier ATN3. In one embodiment, combination attenuator amplifier ATN3 is arranged to selectively provide amplification or attenuation of approximately -25 dB to +25 dB based, at least in part, on a signal strength detected by sensor SNSl. Also, the BANDB signal components go through attenuator ATN4. In one embodiment, the level of attenuation provided by attenuator ATN4 is based, at least in part, on a signal strength detected by sensor SNS2.

After each of the attenuators, the signal components, for example, pass through another PAD-Filter-PAD combination (FL5 for BANDA and FL6 for BANDB). These signal components are then combined in diplexer DIPL4 and then amplified by amplifier AMP2. In one embodiment, amplifier AMP2 is arranged to provide approximately 20 dB of gain.

The signal components are then again split by diplexer DIPL5 and they, for example, pass through another set of PAD Filter PAD filters. The signal components are then combined in diplexer DIPL6 and amplified by amplifier AMP3. In one embodiment, amplifier AMP3 is arranged to provide a gain of approximately 20 dB.

After amplifier AMP3, the signal is then split by diplexer DIPL7 and the BANDA signal component is provided to filter FL9 and power amplifier AMP4. In one embodiment, power amplifier AMP4 provides approximately 23 dB of gain and is a CX65105 available from Skyworks Solutions, Inc of Worburn, Massachusetts. An RF output level of power amplifier AMP4 is sensed by sensor SNS 1. In one embodiment, a DC voltage is provided by sensor SNSl based, at least in part, on the sensed RF output level of power amplifier AMP4. Any suitable circuits, methods, and/or the like, may be employed to provide attenuation control signals based on the output of sensor SNS 1. The BANDA uplink signal component is then provided to BANDA duplexer DUPL3 where it is combined with the BANDA downlink signal component.

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Likewise, the BANDB uplink signal component leaves diplexer DIPL7, is filtered by filter FLlO and amplified by BANDB uplink power amplifier AMP5. In one embodiment, power amplifier AMP5 provides a gain of approximately 28 dB. Also, sensor SNS2 monitors the output level of the BANDB uplink signal component. In one embodiment, a DC voltage is provided by sensor SNS2 based, at least in part, on the sensed RF output level of power amplifier AMP5. Any suitable circuits, methods, and/or the like, may be employed to provide attenuation control signals based on the output of sensor SNS2. The BANDB uplink signal component is then provided to BANDB duplexer DUPL4 where it is combined with the BANDB downlink signal component.

The BANDA signal components are then combined with the BANDB signal components by diplexer DIPL8 before it is provided on signal DOWN to input/output IO2. Input/output 102 may be an antenna, connector, coupled to another amplifier circuit, and/or the like.

Illustrative Downlink Signal Path

In one embodiment, starting from input/output 102, the BANDA and BANDB signal components of signal DOWN are first split by diplexer DIPL8 onto separate signals. At this point, the diplexer DIPL8 output signals are bidirectional and include both uplink and downlink signal components. BANDA downlink duplexer DUPL3 then separates the BANDA downlink and uplink signals components onto separate signals. The BANDA downlink signal is then amplified by amplifier AMP6 and filtered by filter FLl 1. In one embodiment, amplifier AMP6 is a low-noise preamplifier circuit that is arranged to provide approximately 20 dB of gain.

The BANDA downlink signal then goes to attenuator ATN5 which selectively controls the signal strength to the following stages based, at least in part, on a signal strength detected by sensor SNS3. From attenuator ATN5 the signal goes to filter FL13. In one embodiment, filter FL13 includes a first 2 dB PAD, a SAW filter, and a second 2 dB PAD. In other embodiments, other filters, such as those discussed above, may be employed as filter FL13.

From diplexer DIPL8, the BANDB downlink signal goes through a similar signal path, including duplexer DUPL4, amplifier AMP7, filter FL12, attenuator ATN6, and filter

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FL 14. In one embodiment, amplifier AMP7 is a low-noise preamplifier circuit that is arranged to provide approximately 20 dB of gain and attenuator ATN7 is arranged to selectively control the signal strength to the following stages based, at least in part, on a signal strength detected by sensor SNS4. However, in other embodiments, the BANDB downlink signal path may be different from the BANDA downlink signal path. In yet other embodiments, the uplink signal paths may be the same as the downlink signal paths.

The BANDA and BANDB downlink signal paths are then combined by diplexer DIPL9. After diplexer DIPL9, the BANDA and BANDB downlink signal components are provided as a signal multi-band signal to amplifier AMP8. In one embodiment, amplifier AMP8 is arranged to amplify the signal by approximately 20 dB. Amplifiers, such as those discussed above, may be suitably employed as amplifier AMP8. The output of amplifier AMP8 is split by diplexer DIPLlO such that the BANDA signal component is provided to filter FLl 5, and the BANDB signal component is provided to filter FL 16 prior to being recombined by diplexer DIPLl 1. The multi-band output signal from diplexer DIPL 11 is then amplified approximately 20 dB by amplifier AMP9.

The output of amplifier AMP9 is split by diplexer DIPL 12 such that the BANDA signal component is provided to attenuator ATN7, and the BANDB signal component is provided to attenuator ATN8. In one embodiment, attenuator ATN7 is a combination amplifier/attenuator which provides signal gain or attenuation based, at least in part, on the output of sensor SNS3. Also, attenuator ATN8 provides attenuation based, at least in part, on the output of sensor SNS4.

The outputs of attenuators ATN7 and ATN8 are respectively provided to filters FL 17 and FL 18 before being combined by diplexer DIPL13.

After diplexer DIPL 13, the multi-band output of diplexer DIPL 13 is amplified by amplifier AMPlO. In one embodiment, amplifier AMPlO is arranged to provide amplification of approximately 2OdB.

The output of amplifier AMPlO is split by diplexer DIPL 14 for filtering. The BANDA signal component is filtered by filter FL 19 and amplified by the BANDA downlink power amplifier AMPl 1. An RF output level of power amplifier AMPl 1 is sensed by sensor SNS3. In one embodiment, a DC voltage is provided by sensor SNS3 based, at least in part,

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3366213 1 9609309-000 Docket No.: 2207746-WOO on the sensed RF output level of power amplifier AMPl 1. Any suitable circuits, methods, and/or the like, may be employed to provide attenuation control signals based on the output of sensor SNS3. The BANDA downlink signal component is then provided to BANDA duplexer DUPLl where it is combined with the BANDA uplink signal component.

Likewise, the BANDB signal component is filtered by filter FL20 and amplified by the BANDB downlink power amplifier AMP 12. An RF output level of power amplifier AMP 12 is sensed by sensor SNS4. In one embodiment, a DC voltage is provided by sensor SNS4 based, at least in part, on the sensed RF output level of power amplifier AMP 12. Any suitable circuits, methods, and/or the like, may be employed to provide attenuation control signals based on the output of sensor SNS4. The BANDB downlink signal component is then provided to BANDB duplexer DUPL2 where it is combined with the BANDB uplink signal component.

The BANDA signal components are then combined with the BANDB signal components by diplexer DIPLl before it is provided on signal UP to input/output IOl . Input/output IOl may be an antenna, connector, coupled to another amplifier circuit, and/or the like.

The above specification, examples and data provide a description of the method and applications, and use of the invention. Since many embodiments of the invention can be made without departing from the spirit and scope of the invention, this specification merely set forth some of the many possible embodiments for the invention.

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Claims

Docket No.: 2207746-WOOCLAIMSWhat is claimed as new and desired to be protected by Letters Patent of the United States is:

1. An apparatus for amplifying a signal, comprising: a first multiplexor circuit that is arranged to receive a multi-band input signal and to provide a plurality of single-band signals; a first filter circuit that is coupled to the first multiplexor circuit and is arranged to receive a first single-band signal of the plurality of single- band signals and to provide a first filtered single-band signal; a second filter circuit that is coupled to the first multiplexor circuit and is arranged to receive a second single -band signal of the plurality of single-band signals and to provide a second filtered single-band signal; a second multiplexor circuit that is coupled to the first filter circuit and coupled to the second filter circuit, and is arranged to receive the first and the second filtered single-band signals and to provide a combined multi-band signal based on the first and the second filtered single-band signals; an amplifier circuit that is coupled to the second multiplexor circuit and is arranged to multiply the combined multi-band signal with a gain multiplier to provide an amplified signal; and a third multiplexor that is coupled to the amplifier circuit and is arranged to receive the amplified signal and to provide a first output signal and a second output signal, wherein each of the first output signal and the second output signal are single-band signals.

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