Efficient Multi-Band Transmitter

Abstract

The transmitter, sensor system, and method of transmission include a frequency adjuster connected to a ring oscillator for reducing latency and power consumption and for receiving a signal from the ring oscillator, the frequency adjuster having a plurality of logic circuits for adjusting the signal to a selected transmission frequency band, a band switch connected to the ring oscillator and the frequency adjuster for selecting logic circuits in the frequency adjuster to determine the selected one of the transmission frequency bands from a plurality of output frequency bands, and a first radio front end connected to the frequency adjuster for transmitting the signal in the selected one of the transmission frequency bands.

Description

[Technical Field]

[0001] The present invention relates generally to transmitter architectures, and more particularly to efficient multi-band transmitters. [Background technology]

[0002] Low-power sensor arrays are increasingly being used for a variety of applications, including internet of things (IoT) devices, implantable devices, wearable devices, energy harvesting systems, seismic sensors, structural health monitoring systems, and multi-channel / multi-mode devices, among others. Such transmitters may need to transmit in a variety of different frequency bands according to the requirements of the particular application. Summary of the Invention [Means for solving the problem]

[0003] The transmitter includes a frequency adjuster connected to a ring oscillator for reducing latency and power consumption and for receiving a signal from the ring oscillator, the frequency adjuster including a plurality of logic circuits for adjusting the signal to a selected one of the transmit frequency bands, a band switch connected to the ring oscillator and the frequency adjuster for selecting logic circuits in the frequency adjuster to determine the selected one of the transmit frequency bands from a plurality of output frequency bands, and a first radio front end connected to the frequency adjuster for transmitting the signal in the selected one of the transmit frequency bands.

[0004] The sensor system includes a sensor that generates measurement data, a ring oscillator-based transmitter, and an antenna that receives the transmitted modulated signal. The ring oscillator-based transmitter includes a frequency adjuster, a band switch, and a first radio front-end. The frequency adjuster is connected to the ring oscillator to reduce latency and power consumption and to receive signals from the ring oscillator. The frequency adjuster includes a plurality of logic circuits for adjusting the signals to a selected one of the transmission frequency bands. The band switch is connected to the ring oscillator and the frequency adjuster to select logic circuits in the frequency adjuster to determine the selected one of the transmission frequency bands from a set of a plurality of output frequency bands. The first radio front-end is connected to the frequency adjuster to modulate the measurement data onto the signal and transmit the signal in the selected one of the transmission frequency bands.

[0005] A method for transmitting a signal includes tuning a ring oscillator output to a fundamental frequency to reduce latency and power consumption, switching the ring oscillator output to a selected one of the transmission bands using a frequency adjuster, adjusting the ring oscillator output to a second frequency on the selected one of the transmission bands using multiple phase outputs of the ring oscillator, and transmitting the adjusted signal in the selected transmission band.

[0006] The method can be performed by a computer program when the computer program is run on a computer.

[0007] These and other features and advantages will become apparent from the following detailed description of illustrative embodiments, which is to be read in connection with the accompanying drawings.

[0008] The following description will provide details of preferred embodiments with reference to the accompanying drawings. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a block diagram of a transmission system in accordance with an embodiment of the present invention that uses a ring oscillator to generate a fundamental frequency that is then tuned to one of a set of different transmission bands. [Figure 2] FIG. 2 is a schematic diagram of a ring oscillator that can be used to generate a fundamental frequency for a digitally synthesizable transmitter, in accordance with an embodiment of the present invention. [Figure 3] FIG. 3 is a block diagram of a frequency adjuster that adjusts the fundamental frequency to a selected transmit frequency according to one embodiment of the present invention. [Figure 4] FIG. 4 is a block diagram of a transmission system in which a ring oscillator is used to generate a fundamental frequency that is then tuned to one of a set of different transmission bands, in accordance with one embodiment of the present invention. [Figure 5] FIG. 5 is a schematic diagram of a matching network that accepts inputs from a set of different drivers operating at different frequencies and matches them to an antenna in accordance with one embodiment of the present invention. [Figure 6] FIG. 6 is a block / flow diagram of a method for transmitting a signal using a ring oscillator to generate a fundamental frequency and then adjusting the fundamental frequency to one of a set of different transmission bands, in accordance with one embodiment of the present invention. [Figure 7] FIG. 7 is a block diagram of a low-power sensor system that uses a ring oscillator-based transmitter to transmit sensor data in any of a set of different transmission bands, according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0010] The transmitter may include a single, low-power-based oscillator that generates a fundamental frequency signal that can be tuned and modulated for transmission across multiple different bands. For example, a ring oscillator operating at approximately 900 MHz can generate a fundamental frequency signal that, when multiplied or divided and appropriately tuned, can be used to transmit in various industrial, scientific, and medical (ISM) radio bands and other useful radio frequencies. Such an architecture can provide high bandwidth and data rates with low power consumption and fast wake-up times, in addition to being able to be deployed in many different environments with heterogeneous hardware.

[0011] Referring now to Figure 1, an exemplary transmitter system 100 is shown. A ring oscillator 102 generates a fundamental frequency signal having a frequency based on the physical characteristics of the oscillator and its components. The fundamental frequency signal is adjusted in a frequency adjuster 104, for example, by multiplying or dividing the frequency of the fundamental frequency signal, before being passed to a transmitter array 106. Each transmitter array 106 is configured to transmit signals using one or more antennas 108 in different respective frequency bands. Each of these components is described in more detail below.

[0012] Although multiple different transmitter arrays 106 (also known as radio front ends) are shown, it should be understood that each transmitter array 106 has a respective set of antennas 108, as described in more detail below, and other embodiments may include a single radio front end with multiple drivers, each handling a different respective frequency, and using a multiple-input matching network to feed a single antenna system.

[0013] Referring now to FIG. 2, an exemplary ring oscillator 102 is shown. The ring oscillator 102 may be formed as a series of inverters 202 with feedback, such that the output of the last inverter 202 feeds back to the input of the first inverter 202. An odd number of inverters 202 may be used, such that when the last inverter 202 inverts its input signal, it inverts the input signal to the first inverter 202. As a result, the output signal 204 of the ring oscillator 102 inverts periodically, where the period depends on the number of inverters 202 in the ring oscillator 102 and the signal propagation delay associated with each such inverter 202. This is but one contemplated architecture for a ring oscillator. The ring oscillator 102 may have multiple outputs 204, each at a different point in the ring oscillator to provide a different phase.

[0014] The inverters 202 may be implemented, for example, as complementary metal-oxide semiconductor (CMOS) inverters. Such a structure may be formed from a series-connected p-channel metal-oxide semiconductor (PMOS) transistor and an n-channel metal-oxide semiconductor (NMOS) transistor. Each transistor turns on when it reaches its threshold voltage, thereby changing the output of its delay stage. A small amount of time is required for charge to accumulate to this point, constituting an inversion delay. Thus, each inverter 202 contributes to the total period of the ring oscillator 102. This delay can be adjusted by affecting the delay of each inverter stage 202, for example, by changing the bias voltage value or by changing the capacitance. Thus, a full range of different frequencies can be generated by the ring oscillator 102, depending on the delay of each inverter. While a CMOS-based inverter is specifically contemplated, it should be understood that any suitable delay element may be used instead of this structure.

[0015] A voltage 206 may be applied to initiate oscillation, which continues as long as the voltage is maintained. Additionally, frequency can be tuned by varying the input voltage, which changes the signal propagation delay of the inverter 202. Increasing the input voltage may decrease the signal propagation delay, thereby increasing the frequency of the output signal 204. This voltage may be approximately 0.5 V, allowing the oscillator to operate from a low-voltage power source, such as a solar cell, coin battery, or energy harvester. With such low-power operation, ring oscillator-based transistors may be useful in embedded sensor systems where only limited power is available and where manually replacing a depleted power source may be inconvenient.

[0016] The frequency may also be tuned by controlling an array of tuning capacitors, where each capacitor in the array is associated with a respective inverter 202. The tuning capacitors control the rate at which each inverter 202 charges, and therefore the rate at which the signal propagates through the ring oscillator 102.

[0017] These tuning capacitors may have capacitances that can be switched between high and low capacitance modes, providing a frequency tuning range between a state in which all of the inverters 202 have their respective tuning capacitors in the high capacitance mode and a state in which all of the inverters 202 have their respective tuning capacitors in the low capacitance mode. Operation of the tuning capacitors thereby varies the inversion delay of each inverter 202 between high and low capacitance values. The resulting frequency of the ring oscillator 102 can then be determined by the following equation:

number

[0018] The ring oscillator 102 may stabilize within one clock period of the clock frequency. For example, if the ring oscillator operates at 2 GHz, it will stabilize within approximately 500 ps. This contrasts with an L / C oscillator, which may require a time that is a multiple of the fundamental period, depending on the quality factor of the L / C oscillator's resonator tank. For example, an L / C oscillator may require 5 ns for a quality factor of 10. The shorter wake-up time of a ring oscillator enables transmit and receive functions to be performed with very low latency. As a result, sensor systems using such oscillators for transmission can turn off the oscillator when not needed, providing power savings without sacrificing latency. Additionally, because the oscillator needs to operate for a much shorter time before stabilizing, the ring oscillator may waste significantly less energy during startup than an L / C oscillator.

[0019] By including multiple outputs 204, multiple phases can be extracted from the ring oscillator 102. Different outputs will sample the oscillating signal at different points in its wavelength. Any number of such outputs 204 can be used to establish any number of delay cells. For example, using N delay cells can result in two phases spaced 180 / N degrees apart. Thus, by using two delay cells (two outputs 204), the phases can be spaced 90 degrees apart, i.e., approximately 1 / 4 the length of the ring oscillator 102. In some cases, different outputs 204 can be used to achieve different phase granularities. Any configuration with an even number of equally spaced outputs 204 has outputs spaced 90 degrees apart, which can be used to generate in-phase and quadrature signals.

[0020] The length of the ring oscillator 102 may be selected to generate a fundamental frequency of the output signal 204 that is the geometric mean of the extreme frequencies of the band being used. For example, consider a transmitter 100 transmitting in the following ISM bands: 170 MHz, 315 MHz, 433 MHz, 900 MHz, 2400 MHz, and 5200 MHz. The lowest frequency is 170 MHz, and the highest frequency is 5200 MHz, with the geometric mean value (940 MHz) being close to 900 MHz. Thus, the fundamental frequency of the output signal may be set to 900 MHz, which may be directly utilized for 900 MHz operation, or may be adjusted to operate in a higher or lower frequency band. While these frequency bands are specifically contemplated, it should be understood that any suitable frequency bands, including those above, including those higher than 5200 MHz and those lower than 170 MHz, may be used instead. Additionally, while bands that are approximately integer multiples of each other are specifically contemplated, it should be understood that bands that do not conform to this pattern may be used if appropriate modifications are made to frequency adjustment block 104.

[0021] Referring now to Figure 3, additional details of frequency adjustment block 104 are shown. The output signal 204 from ring oscillator 102 is processed by band switch 301, which is controlled to select which band or bands are used for transmission. In this example, the signal 204 from the ring oscillator may be set to a fundamental frequency of 900 MHz. Frequency adjustment block 104 takes a single input and produces one of five different outputs corresponding to five different bands. It should be understood that more or fewer bands may alternatively be used depending on the communication needs of the device.

[0022] A set of frequency adjusters is shown that converts the fundamental frequency of signal 204 to a transmission band selected from a set of different bands. For example, with a 900 MHz input, a divide by five frequency divider 302 generates a signal 303 at 180 MHz, which can be tuned to a 170 MHz band range. A divide by three frequency divider 304 generates a signal 305 at 300 MHz, which can be tuned to a 315 MHz band range. A buffer 306 can be used to provide an output signal 307 at 900 MHz, the same as signal 204 from ring oscillator 102. A multiply by three frequency multiplier 308 generates a signal 309 at 2700 MHz, which can be tuned to a 2400 MHz band range. A multiply by five frequency multiplier 310 generates a signal 311 at 5400 MHz, which can be tuned to the 5200 MHz range. Other frequencies, such as a 433 MHz output, can be reached using similar circuitry. For example, a 433 MHz output can be generated by dividing the frequency of the output signal 204 by two, which produces 450 MHz, which can be tuned to the 433 MHz range.

[0023] For example, divide-by-5 ​​frequency divider 302 and divide-by-3 frequency divider 304 may be implemented with a frequency divider and capacitive digital to analog converter phase multiplexer, which can divide the fundamental frequency into any suitable fraction. This can be done by using multiple phases from ring oscillator 102 and generating a sinusoidal signal with the capacitive digital to analog converter.

[0024] For frequency multiplication, signals with quadrature phases can be merged to provide an output signal at a multiple of the frequency of the input signal. Such quadrature phases can be generated from different outputs 204 of the ring oscillator 102. For higher frequency outputs, filtering can be performed using passive elements at resonance. Thus, the frequency multiplier can be implemented, for example, as a separate logic circuit. For example, an XOR circuit with phase-shifted inputs can be used. As one example, an XOR3 circuit can multiply the frequency of an input by a factor of three if the input signal is applied to the three inputs of the XOR3 circuit with different amounts of phase shift.

[0025] Referring now to FIG. 4, an exemplary transmitter system 400 is shown. Rather than feeding a separate transmitter array, in this case, the frequency adjustment block 104 may output to a transmitter array 402 having multiple drivers 404. Each driver 404 may receive a different respective frequency input from the frequency adjustment block 104. The multiple drivers 404 may then output a respective transmit signal. Each of the multiple drivers 404 may be individually configured, for example, as a single-ended driver or a differential driver. A matching network 406 matches impedance between the operating driver 404, which provides transmission at the respective input frequency, and an antenna 408 or antenna array.

[0026] During operation, any of the multiple drivers 404 may be enabled at a given time, while the rest are turned off. The antenna 408 may be a wideband antenna supporting closely spaced frequency bands covering a tuning range of a fundamental frequency. Following the above example of a band of use, the antenna 408 may have a standing wave ratio (SWR) of less than 1:1.5 over an exemplary frequency range of 868 to 915 MHz. The matching network 406 provides resonance at each of the input frequencies. Therefore, the on-chip drivers can be configured as single-ended or differential, as desired.

[0027] 5, additional details of the matching network 406 are shown. The matching network 406 is configured to accept inputs from all of the different drivers 404, with the number of connections between the multiple drivers 404 and the matching network 406 reflecting whether each driver 404 is in a single-ended or differential configuration. For simplicity, only a subset of the drivers 404 are shown in FIG. 5, but it should be understood that any number of drivers 404 may be connected to such a matching network 406.

[0028] A set of drivers 404 operating at different respective frequencies provide inputs to a matching network 406 at different stages, where the inductors 502 and capacitors 504 have values ​​selected to provide impedance matching to a single output impedance 506 that matches the antenna 408. As shown, the first and third drivers 404 are configured to provide differential outputs, while the second driver 404 is configured to provide a single-ended output. The inductors 502 may have an exemplary inductance of about 1 nH to about 5 nH, and the capacitors 504 may have an exemplary capacitance of about 1 pF to about 3 pF. These values ​​are selected to properly tune the effective impedance of the antenna 408 for resonance with the output frequency of the selected drivers 404.

[0029] 6, a method for transmitting a signal is shown. Block 602 determines an operating frequency among a plurality of available bands and a respective frequency range for each of the plurality of available bands. This selection may be made according to any of a number of factors, including, for example, the operating frequencies of devices available in the environment, regulatory considerations, noise levels, etc.

[0030] Next, block 604 tunes the ring oscillator 102 to generate a corresponding frequency on the baseband. For example, if a frequency is selected in the 170 MHz band, block 604 tunes the local ring oscillator 102 to a frequency that, when adjusted by frequency adjuster 104, generates the operating frequency. As described above, this can be done by adjusting the capacitance in each delay stage of the ring oscillator 102.

[0031] Block 606 then operates band switch 301 to connect one or more outputs of the local oscillator to respective modulation blocks corresponding to the band encompassing the operating frequency. In some cases, this band switch 301 may comprise a switch that selectively connects the local oscillator to the respective modulation block. In some cases, band switch 301 may control power to the respective transmitter array 106 or respective driver 404 corresponding to the operating frequency.

[0032] Block 608 modulates the modified signal with any suitable data signal using any suitable modulation scheme. For example, quadrature amplitude modulation (QAM) may be used to encode data into the signal by varying the amplitude of in-phase and quadrature versions of the signal. It should be understood that many modulation schemes exist and that any suitable modulation scheme may be selected according to design priorities and channel characteristics. In another example, phase-shift keying may be used, for example, by adjusting the phase of a phase-locked loop. Modulation may be performed at any suitable stage after the frequency has been adjusted.

[0033] Block 610 then transmits the modulated signal. This transmission may be performed using one or more antennas in, for example, a phased array configuration to provide a signal directed toward a particular target. Thus, block 610 may configure one or more antennas according to a particular beam steering direction by providing different respective antennas with multiple output signals that are phase shifted relative to one another.

[0034] In some cases, the entire transmitter and receiver can be synthesized in digital logic. This is particularly useful for designing radios in scaled CMOS nodes and for reducing time-to-market solutions. The entire radio can be designed using standard logic cells available in digital technology and can target low power.

[0035] The present invention may be a system, method, or computer program product, or combination thereof, at any level of technical detail that may be integrated. The computer program product may include one or more computer-readable storage media having computer-readable program instructions for causing a processor to perform aspects of the present invention.

[0036] The computer-readable storage medium can be a tangible device that can hold and store instructions for use by an instruction-execution device. The computer-readable storage medium can be, for example, but not limited to, an electronic storage device, a magnetic storage device, an optical storage device, an electromagnetic storage device, a semiconductor storage device, or any suitable combination thereof. A non-exhaustive list of more specific examples of the computer-readable storage medium includes the following: a portable computer diskette (登録商標), hard disk, random access memory (RAM), read only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), static random access memory (SRAM), portable compact disc read-only memory (CD-ROM), digital versatile disk (DVD), memory stick, floppy disk, mechanically encoded device such as punch cards or raised structures in grooves on which instructions are recorded, or any suitable combination thereof. As used herein, the computer-readable storage medium should not be construed to be a transitory signal per se, such as an electric wave or other freely propagating electromagnetic wave, an electromagnetic wave propagating through a waveguide or other transmission medium (e.g., light pulses passing through a fiber optic cable), or an electrical signal transmitted over an electrical wire.

[0037] The computer-readable program instructions described herein can be downloaded from a computer-readable storage medium to each computing device / processing device, or to an external computer or external storage device via a network, such as the Internet, a local area network, a wide area network, or a wireless network, or a combination thereof. The network may be comprised of copper transmission cables, optical fiber transmissions, wireless transmissions, routers, firewalls, switches, gateway computers, or edge servers, or a combination thereof. A network adapter card or network interface in each computing device / processing device receives the computer-readable program instructions from the network and transmits the computer-readable program instructions for storage in a computer-readable storage medium within the respective computing device / processing device.

[0038] The computer-readable program instructions for carrying out the operations of the present invention may be either assembler instructions, instruction-set-architecture (ISA) instructions, machine instructions, machine-dependent instructions, microcode, firmware instructions, state-setting data, configuration data for an integrated circuit, or source or object code written in any combination of one or more programming languages, such as object-oriented programming languages, e.g., Smalltalk, C++, etc., or conventional procedural programming languages ​​(e.g., the "C" programming language or similar programming languages). The computer-readable program instructions may be executed entirely on the user's computer, partially on the user's computer, partially on the user's computer as a standalone software package, partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In the latter scenario, the remote computer may be connected to the user's computer via any kind of network, such as a local area network (LAN) or a wide area network (WAN), or the connection may be to an external computer (e.g., over the Internet using an Internet Service Provider). In some embodiments, electronic circuits, such as programmable logic circuits, field-programmable gate arrays (FPGAs), or programmable logic arrays (PLAs), may execute computer-readable program instructions by utilizing state information of the computer-readable program instructions to personalize the electronic circuitry to perform aspects of the invention.

[0039] Aspects of the present invention are described herein with reference to flowchart illustrations or block diagrams, or combinations thereof, of methods, apparatus (systems), and computer program products or computer programs according to embodiments of the invention. It will be understood that each block of the flowchart illustrations or block diagrams, or combinations thereof, and combinations of blocks in the flowchart illustrations or block diagrams, or combinations thereof, can be implemented by computer-readable program instructions.

[0040] These computer-readable program instructions may be provided to a processor of a computer or other programmable data processing apparatus, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions / acts identified in one or more blocks of the flowchart diagrams or block diagrams, or a combination thereof, to produce a machine. These computer-readable program instructions may also be stored in a computer-readable storage medium that can direct a computer-programmable data processing apparatus or other device, or a combination thereof, to function in a particular manner, such that a computer-readable storage medium having stored instructions includes an article of manufacture including instructions that implement aspects of the functions / acts identified in one or more blocks of the flowchart diagrams or block diagrams, or a combination thereof.

[0041] The computer-readable program instructions may also be loaded onto a computer, other programmable data processing apparatus, or other device such that the instructions, which execute on the computer, other programmable data processing apparatus, or other device, implement the functions / acts identified in one or more blocks of the flowchart diagrams or block diagrams, or combinations thereof, to cause the computer, other programmable apparatus, or other device to perform a series of operational steps to generate a computer-implemented process.

[0042] References herein to "one embodiment" or "an embodiment" of the present invention, as well as other variations thereof, mean that a particular feature, structure, characteristic, etc. described in connection with an embodiment is included in at least one embodiment of the present invention. Thus, the appearances of the phrases "in one embodiment" or "in an embodiment" in various places throughout this specification, as well as other variations, do not necessarily all refer to the same embodiment.

[0043] It should be understood that the use of any of " / ", "and / or", "at least one of", e.g., "A / B", "A and / or B", "at least one of A and B" is intended to encompass the selection of only the first listed alternative (A), or the selection of only the second listed alternative (B), or the selection of both alternatives (A and B). As a further example, "A, B and / or C" and "at least one of A, B and C" are intended to encompass the selection of only the first listed alternative (A), or the selection of only the second listed alternative (B), or the selection of only the third listed alternative (C), or the selection of only the first and second alternatives (A and B), the selection of only the first and third alternatives (A and C), the selection of only the second and third alternatives (B and C), or the selection of all three alternatives (A, B and C). This may be expanded by the number of items listed, as would be readily apparent to one of ordinary skill in this and related arts.

[0044] The flowcharts and block diagrams in the figures illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products or computer programs according to various embodiments of the present invention. In this regard, each block in the flowcharts or block diagrams may represent a module, segment, or portion of instructions, which includes one or more executable instructions for implementing one or more specified logical functions. In some alternative implementations, the functions shown in the blocks may occur out of the order shown in the figures. For example, two blocks shown in succession may actually be accomplished as a single step performed simultaneously, substantially simultaneously, partially, or fully in a time-overlapping manner, depending on the functionality involved, or the blocks may be performed in the reverse order. It should be noted that each block of the block diagrams or flowchart diagrams or combinations thereof, and combinations of multiple blocks in the block diagrams or flowchart diagrams or combinations thereof, may be implemented by a special-purpose hardware-based system that performs the specified functions or operations, or may execute a combination of special-purpose hardware and computer instructions.

[0045] As used herein, the terms "hardware processor subsystem" or "hardware processor" can refer to a processor, memory, software, or combination thereof, working together to perform one or more specific tasks. In useful embodiments, the hardware processor subsystem can include one or more data processing elements (e.g., logic circuits, processing circuits, instruction execution devices, etc.). The one or more data processing elements can include a central processing unit, a graphics processing unit, or a separate processor or computing element-based controller (e.g., logic gates, etc.), or a combination thereof. The hardware processor subsystem can include one or more on-board memories (e.g., cache, dedicated memory array, read-only memory, etc.). In some embodiments, the hardware processor subsystem can include one or more memories (e.g., ROM, RAM, basic input / output system (BIOS), etc.), which can be on-board or off-board or dedicated for use by the hardware processor subsystem.

[0046] In some embodiments, the hardware processor subsystem may include and execute one or more software elements, which may include an operating system, one or more applications, or specific code, or any combination thereof, to achieve a specified result.

[0047] In other embodiments, the hardware processor subsystem may comprise dedicated, specialized circuitry that performs one or more electronic processing functions to achieve a specified result. Such circuitry may comprise one or more application-specific integrated circuits (ASICs), FPGAs, or PLAs, or any combination thereof.

[0048] These and other variations of the hardware processor subsystem are also contemplated according to multiple embodiments of the present invention.

[0049] Referring now to FIG. 7, an exemplary low-power sensor system 700 is shown. The system 700 includes a hardware processor 702 and a memory 704. The sensor 706 may include one or more sensor components, each providing a measurement of one or more phenomena. For example, the sensor 706 may be an electromagnetic sensor capable of detecting electromagnetic radiation, such as an infrared sensor or an optical sensor. Other examples of sensors include pressure sensors, sound sensors, vibration sensors, temperature sensors, humidity sensors, chemical sensors, etc. The sensor 706 may be on-board as shown, or may communicate with the system 700 via any suitable communication interface and protocol.

[0050] The power source 708 provides power to the ring oscillator-based multi-band transmitter 710. The power source 708 can be any suitable power source, such as a battery, a solar cell, a vibration generator, a piezoelectric generator, any suitable on-board or off-board generator, or an external power source. It is specifically contemplated that the power source 708 may have a relatively small size, allowing the system 700 to be implemented in a cost-effective and space-efficient manner.

[0051] The transmitter 710 uses the ring oscillator 102 to provide a fundamental frequency signal in a more efficient manner than an L / C tank oscillator. The transmitter 710 conditions the signal from the fundamental frequency to any suitable transmission band. The transmitter 710 may modulate data onto the conditioned signal, for example, modulating the signal to include measurements from the sensor 706.

[0052] The transmitter 710 provides the modulated signal to an antenna 712. The antenna 712 may use any suitable antenna configuration, such as a single wideband antenna or a phased antenna array. In some cases, the antenna 712 may have a different antenna configuration for each band that may be used by the transmitter 710. In some cases, the antenna 712 may have an antenna configuration for a single band, in which case the transmitter 710 may include a matching network 406 to resonate the antenna 712 at the transmit frequency.

[0053] In some cases, the antenna 712 may comprise a phased array having multiple antenna elements. In such cases, each of the multiple antenna elements may transmit the same signal, but phase-shifted by a different amount. The transmitted signals may interfere with each other constructively in some locations and destructively in other locations, potentially providing a highly focused transmission pattern. Therefore, the transmitter 710 may include phase shifters on each transmit path leading to each antenna element of the antenna 712, and the phase values ​​of these phase shifters may be adjusted according to a particular beam pattern.

[0054] Having described a preferred embodiment of an efficient multi-band transmitter, which is illustrative and not intended to be limiting, it should be noted that modifications and variations can be made by those skilled in the art in light of the above teachings. It is therefore to be understood that changes can be made in the particular embodiments disclosed which are within the scope of the invention as outlined by the appended claims. Having thus described aspects of the invention with the detail and particularity required by the patent laws, what is claimed and desired to be protected by Letters Patent is set forth in the appended claims.

Claims

1. A transmitter comprising: a frequency adjuster connected to the ring oscillator for reducing latency and power consumption and for receiving signals from the ring oscillator, the frequency adjuster comprising a plurality of logic circuits for adjusting the signals to a selected one of the transmission frequency bands (hereinafter referred to as the "first transmission frequency band"); a band switch connected to the ring oscillator and the frequency adjuster for selecting logic circuitry within the frequency adjuster to determine the first transmit frequency band from a plurality of output frequency bands; and a first radio front end coupled to the frequency adjuster for transmitting the signal in the first transmission frequency band; It is equipped with The ring oscillator tunes the ring oscillator output to the fundamental frequency signal, thereby turning off oscillators that are not needed, thereby reducing latency and power consumption compared to oscillators that do not tune the ring oscillator output to the fundamental frequency signal. Transmitter.

2. 2. The transmitter of claim 1, wherein the ring oscillator includes a plurality of different phase outputs at a plurality of different points along the length of the ring oscillator, each of the phase outputs providing a different respective phase of a tunable signal, and wherein the frequency adjuster uses the plurality of phases to adjust the signal.

3. 2. The transmitter of claim 1, wherein the ring oscillator comprises a plurality of delay elements, each of the plurality of delay elements having a respective controllable capacitance for adjusting a delay time for tuning.

4. 2. The transmitter of claim 1, wherein the logic circuit comprises a frequency multiplier and a frequency divider having respective outputs in a second frequency band and a third frequency band from the plurality of output frequency bands.

5. 5. The transmitter of claim 4, wherein the frequency multiplier is an XOR circuit that receives multiple different phase inputs from the ring oscillator.

6. the first wireless front end comprises a plurality of drivers; 2. The transmitter of claim 1, wherein the frequency adjuster outputs signals in all of the plurality of output frequency bands to respective drivers of the first radio front end, and wherein the band switch selectively powers one of the drivers according to the selected one of the plurality of output frequency bands.

7. 10. The transmitter of claim 1, further comprising at least one additional radio front end configured to transmit in a different one of the plurality of output frequency bands.

8. 10. The transmitter of claim 1, wherein the transmitter is a digitally synthesized transmitter using digital logic.

9. 1. A sensor system comprising: a sensor for generating measurement data; A ring oscillator-based transmitter, wherein the ring oscillator-based transmitter comprises: a frequency adjuster connected to the ring oscillator for reducing latency and power consumption and for receiving signals from the ring oscillator, the frequency adjuster comprising a plurality of logic circuits for adjusting the signals to a selected one of the transmission frequency bands (hereinafter referred to as the "first transmission frequency band"); a band switch connected to the ring oscillator and the frequency adjuster for selecting logic circuitry within the frequency adjuster to determine the first transmit frequency band from a plurality of output frequency bands; and a first wireless front end coupled to the frequency adjuster for modulating the measurement data onto the signal and for transmitting the signal in the first transmission frequency band; and An antenna that receives the transmitted modulated signal It is equipped with The ring oscillator tunes the ring oscillator output to the fundamental frequency signal, thereby turning off oscillators that are not needed, thereby reducing latency and power consumption compared to oscillators that do not tune the ring oscillator output to the fundamental frequency signal. The sensor system.

10. 10. The sensor system of claim 9, wherein the ring oscillator includes a plurality of different phase outputs at a plurality of different points along a length of the ring oscillator, each of the phase outputs providing a different respective phase of a tunable signal, and wherein the frequency adjuster uses the plurality of phases to adjust the signal.

11. 10. The sensor system of claim 9, wherein the ring oscillator comprises a plurality of delay elements, each of the plurality of delay elements having a respective controllable capacitance for adjusting a delay time for tuning.

12. 10. The sensor system of claim 9, wherein the logic circuit comprises a frequency multiplier and a frequency divider having respective outputs in the second and third frequency bands.

13. The sensor system of claim 12 , wherein the frequency multiplier is an XOR circuit that receives multiple different phase inputs from the ring oscillator.

14. the first wireless front end comprises a plurality of drivers; 10. The sensor system of claim 9, wherein the frequency adjuster outputs signals in all of the plurality of output frequency bands to respective drivers of the first wireless front end, and wherein the band switch selectively powers one of the drivers according to the selected one of the plurality of output frequency bands.

15. The sensor system of claim 9 , further comprising at least one additional wireless front end configured to transmit in a different one of the plurality of output frequency bands.

16. The sensor system of claim 15 , wherein the band switch outputs signals in different ones of the plurality of output frequency bands to different respective radio front ends.

17. 1. A method of transmitting a signal, comprising: Tuning the ring oscillator output to the fundamental frequency to reduce latency and power consumption; switching the ring oscillator output tuned to the fundamental frequency to a selected one of the transmission frequency bands (hereinafter referred to as the "first transmission frequency band") using a frequency adjuster connected to the ring oscillator; tuning the ring oscillator output to a second frequency band above the first transmission frequency band using a plurality of different phase outputs of the ring oscillator output, the plurality of different phase outputs being at a plurality of different points along a length of the ring oscillator, each of the phase outputs providing a different respective phase of a tunable signal; Transmitting a conditioned signal in the first transmission frequency band using a first radio front end. Including, The ring oscillator tunes the ring oscillator output to the fundamental frequency signal, thereby turning off oscillators that are not needed, thereby reducing latency and power consumption compared to oscillators that do not tune the ring oscillator output to the fundamental frequency signal. The method.

18. 20. The method of claim 17, wherein the ring oscillator comprises a plurality of inverter-based delay elements, each delay element including a controllable capacitance.

19. 20. The method of claim 18, wherein tuning the ring oscillator output comprises controlling a controllable capacitance of each of the inverter-based delay elements to adjust an oscillation frequency of the ring oscillator.

20. 20. The method of claim 17, further comprising modulating a data signal onto the regulated ring oscillator output before transmitting the regulated signal.

21. 18. The method of claim 17, wherein the frequency adjuster outputs signals in all of a plurality of output frequency bands to respective drivers of the first radio front end, and wherein a band switch coupled to the ring oscillator and the frequency adjuster selectively powers one of the drivers according to the selected one of the plurality of output frequency bands to select logic circuitry within the frequency adjuster to determine the first transmit frequency band from the plurality of output frequency bands.

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