Sensor circuit with tracking filter and leakage suppression

Abstract

A sensor circuit included in a computer system may include multiple antennas, a control circuit, a mixer circuit, a transmitter circuit, and a filter circuit. The control circuit may generate a baseband signal, and the mixer circuit may modulate the baseband signal using a modulation signal to generate a transmit signal. The transmitter circuit may use a first antenna to transmit the transmit signal. The filter circuit may be configured to track the carrier frequency of the transmit signal and filter a reflected version of the transmit signal to generate an output signal.

Description

Background Art Technical Field

[0002] The present disclosure relates to sensor circuits in computer systems, and more particularly, to radio frequency sensor circuit operations. Background Art

[0003] The modem computer system may perform certain tasks or operations in response to changes in the environment in which the computer system is located. For example, changes in ambient light may cause the computer system to adjust the brightness of the display. Additionally, changes in temperature may cause the computer system to adjust the level of processing being performed in order to keep the computer system within specified thermal limits. In some cases, rapid changes in acceleration may cause the computer system to take certain actions to prevent damage to movable components within the computer system.

[0004] In order to react to environmental changes, a computer system may include a plurality of sensor circuits designed to detect various effects or conditions. For example, such sensor circuits may include temperature sensors, acceleration sensors, ambient light sensors, etc. The outputs of such sensor circuits may be polled by a processor or controller included in the computer system to determine an action to be performed.

[0005] Sensor circuits (such as those described above) may include any suitable combination of logic circuits, analog circuits, radio frequency circuits, etc. In some cases, sensor circuits may employ passive sensing techniques. Other sensor circuits may employ active sensing by transmitting a signal and monitoring any return signal. Summary of the invention

[0006] The present invention discloses various embodiments of sensor circuits. Broadly speaking, the sensor circuit may include a first antenna and a second antenna, and a control circuit that may be configured to generate a baseband signal. The transmitter circuit may be configured to transmit a transmit signal via the first antenna, and the transmit signal is a modulated version of the baseband signal. A filter circuit that tracks the carrier frequency of the transmit signal may be configured to filter an echo signal received via the second antenna to generate an output signal, wherein the echo signal is a reflected version of the transmit signal. In another embodiment, the filter circuit may include a second mixer circuit, and the second mixer circuit may be configured to use the modulated signal to down-convert the echo signal to generate an intermediate signal. In different embodiments, the filter circuit may also include an amplifier circuit, and the amplifier circuit is configured to amplify the intermediate signal to generate an output signal. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 is a block diagram of an implementation of a sensor circuit.

[0008] Figure 2A block diagram of an embodiment of a baseband amplifier circuit is shown.

[0009] Figure 3 A block diagram of another embodiment of a baseband amplifier circuit is shown.

[0010] Figure 4 A block diagram of the control circuit is shown.

[0011] Figure 5 Exemplary transmit and echo waveforms are shown.

[0012] Figure 6 Exemplary waveforms of the transfer function of a sensor circuit employing a tracking filter are shown.

[0013] Figure 7 Exemplary waveforms of transfer functions of a sensor circuit with leakage suppression are shown.

[0014] Figure 8 A flow chart depicting an embodiment of a method for operating a tracking filter in a sensor circuit is shown.

[0015] Fig. 9 A flow chart depicting an embodiment of a method for operating a radio frequency sensor circuit with leakage suppression is shown.

[0016] Fig.10 is a block diagram of one embodiment of a computer system including a power generator circuit.

[0017] Although the present disclosure is susceptible to various modifications and alternative forms, the specific embodiments thereof are shown by way of example in the accompanying drawings and will be described in detail herein. However, it should be understood that the accompanying drawings and specific embodiments are not intended to limit the present disclosure to the specific forms illustrated, but on the contrary, their purpose is to cover all modifications, equivalents and alternative forms falling within the essence and scope of the present disclosure defined by the appended claims. The titles used herein are only for organizational purposes and are not intended to be used to limit the scope of the specification. As used throughout this patent application, the word "may" is used in an allowed sense (i.e., meaning with possibility) rather than a mandatory sense (i.e., meaning must). Similarly, the word "includes" means including but not limited to.

[0018] Various units, circuits or other components may be described as being "configured to" perform one or more tasks. In such contexts, "configured to" is a broad statement of a structure that generally means "having" a "circuit" that performs one or more tasks during operation. In this way, even when the unit / circuit / component is not currently connected, the unit / circuit / component may be configured to perform a task. Typically, the circuit that forms the structure corresponding to "configured to" may include a hardware circuit. Similarly, for convenience in description, various units / circuits / components may be described as performing one or more tasks. Such descriptions should be interpreted as including the phrase "configured to". The statement that the unit / circuit / component configured to perform one or more tasks is explicitly intended to not invoke the interpretation of paragraph f of 35 U.S.C. §112 for the unit / circuit / component. More generally, the statement of any element is explicitly intended not to invoke the interpretation of paragraph f of 35 U.S.C. §112 for the element, unless the language of "device for..." or "step for..." is specifically stated.

[0019] As used herein, the term "based on" is used to describe one or more factors that influence a determination. This term does not exclude that there may be additional factors that may influence the determination. That is, the determination may be based only on the specified factors or on the specified factors and other unspecified factors. Consider the phrase "A is determined based on B." This phrase specifies that B is a factor used to determine A or that B influences the determination of A. This phrase does not exclude that the determination of A may also be based on some other factor such as C. The phrase is also intended to cover embodiments in which A is determined based only on B. The phrase "based on" is therefore synonymous with the phrase "based at least in part on." DETAILED DESCRIPTION

[0020] Many computer systems are equipped with various sensors that allow such computer systems to detect various effects and conditions. For example, some mobile computer systems include sensors for detecting acceleration and deceleration, ambient temperature, humidity, etc. In some cases, computer systems include sensors for determining the distance to a particular object. For example, a mobile computer system may employ sensors to determine the distance to a desktop computer system, a router, etc.

[0021] Sensors used to determine the distance or range to an object may typically employ radio frequency (RF) signals. Such signals may be transmitted, and echo signals (i.e., versions of the transmitted signals reflected from an object) may be received and analyzed to determine the distance or range to the object.

[0022] In some cases, the transmit signal occupies a large RF bandwidth, but the baseband signal used by the sensor circuit occupies a portion of the RF bandwidth occupied by the transmit signal. Therefore, the amplifier circuit included in the sensor circuit is designed to operate over the entire RF bandwidth occupied by the transmit signal, making it susceptible to interference. In addition, in some applications, it is difficult to isolate the transmit antenna from the receive antenna. Some of the transmit signals may be directly received by the receive antenna, which may be interpreted as a target or object at zero distance. The embodiments shown in the accompanying drawings and described below may provide a technique for operating a sensor circuit that filters the received echo signal to remove unwanted interference and the transmit signal directly received by the receive antenna, thereby improving the noise suppression of the sensor circuit and improving the accuracy of the sensor circuit's determination of the distance to the target.

[0023] exist Figure 1 A block diagram of a sensor circuit is depicted in As shown, the sensor circuit 100 includes a transmitter circuit 102 , antennas 103 and 104 , a filter circuit 105 , and a control circuit 106 .

[0024] The control circuit 106 is configured to generate a baseband signal 107. The transmitter circuit 102 is configured to transmit a transmit signal 108 via the antenna 103. In various embodiments, the transmit signal 108 may be a modulated version of the baseband signal 107. Note that in some embodiments, a mixer circuit configured to modulate the baseband signal 107 to generate the transmit signal 108 may be included between the control circuit 106 and the transmitter circuit 102. As described in more detail below, the control circuit 106 may be further configured to use the output signal 111 to generate a plurality of data bits, and use the plurality of data bits to determine information indicating a distance to an object that reflected the transmit signal to create an echo signal.

[0025] In various embodiments, the echo signal 109 is a reflected version of the transmit signal 108 generated when the transmit signal 108 is reflected from a particular object or target. The sensor circuit 100 uses the antenna 104 to receive the echo signal 109, and the filter circuit 105 is configured to filter the echo signal 109 to generate an output signal 111. In some cases, the filter circuit 105 can be a specific embodiment of a tracking filter that tracks the carrier frequency of the transmit signal 108.

[0026] As described in more detail below, filter circuit 105 may include a mixer circuit configured to down-convert echo signal 109 using modulation signal 110 to generate an intermediate signal. In some cases, filter circuit 105 may be configured to suppress at least one frequency component of echo signal 109 generated by receiving transmit signal 108 directly from antenna 103 via antenna 104.

[0027] Go to Figure 2 , a block diagram of an embodiment of a filter circuit is shown. In various embodiments, the filter circuit 200 may correspond to Figure 1 Filter circuit 105 is depicted. As shown, filter circuit 200 includes amplifier circuit 201, impedance 202, capacitor 203 and mixer circuit 204. Figure 2 In the illustrated embodiment, each of the echo signal 109, the intermediate signal 206, and the output signal 11 are encoded differently on a pair of signal lines.

[0028] Mixer circuit 204 is configured to generate intermediate signal 206 using echo signal 109 and modulation signal 110. In various embodiments, the frequency of intermediate signal 206 may be the difference between the frequencies of echo signal 109 and modulation signal 110, thereby substantially shifting the frequency of echo signal 109 in a process generally referred to as "heterodyning."

[0029] In various embodiments, mixer circuit 204 may be a specific embodiment of a passive mixer. As used herein, a passive mixer circuit is transparent input to output and output to input. For example, mixer circuit 204 may include any suitable combination of passive circuit elements and active circuit elements that allow bidirectional flow of signals from input to output and vice versa.

[0030] The amplifier circuit 201 is configured to amplify the intermediate signal 206 to generate the output signal 111. In various embodiments, the amplifier circuit 201 can be a specific embodiment of a differential amplifier, or other suitable circuit configured to generate an output signal whose magnitude is represented as the difference between the voltage levels of two signal lines. In other embodiments, the amplifier circuit 201 can be single-ended to generate the output signal 111 based on the magnitude of the echo signal 109 relative to the ground reference or ground supply signal. In some cases, the amplifier circuit 201 can be classified as a high impedance amplifier that only allows leakage current on its input. As shown, the magnitude of the output signal 111 is the voltage difference between the signal lines of the intermediate signal 206 multiplied by the gain factor of the amplifier circuit 201.

[0031] In various embodiments, amplifier circuit 201 may include a plurality of transconductance elements or other gain devices. For example, amplifier circuit 201 may include a plurality of metal oxide semiconductor field effect transistors (MOSFETs), bipolar transistors, or other devices compatible with any other suitable semiconductor manufacturing process used to manufacture sensor circuit 100.

[0032] The combination of mixer circuit 204 and amplifier circuit 201 may be implemented as a narrowband filter whose center frequency tracks changes in the carrier frequency of transmit signal 108. As used herein, a filter circuit whose center frequency tracks changes in the frequency of a particular signal (also referred to as a "tracking filter") refers to a filter circuit whose center frequency changes the frequency of the particular signal after a certain period of time. The response time of the tracking filter may be quite fast. For example, in some embodiments, the center frequency of the tracking filter may change within a few nanoseconds of the frequency change of the particular signal.

[0033] In some cases, the width of the narrowband filter formed by the combination of mixer circuit 204 and amplifier circuit 201 can be as small as a few hundred kilohertz. Figure 6 An example of a transfer function of the filter circuit 200 is described in more detail. By employing such a narrowband filter, the ability of the sensor circuit 100 to suppress interference from other sources (e.g., radio) is improved. In addition, the linearity of the receiver portion of the sensor circuit 100 is further improved using the combination of the mixer circuit 204 and the amplifier circuit 201.

[0034] Impedance 202 is coupled between the output signal line of amplifier circuit 201. In various embodiments, impedance 202 may be a specific implementation of a resistor and may be used as part of an impedance matching network (which may include capacitor 203) for matching the output impedance of amplifier circuit 201 to the input impedance in control circuit 106. In some cases, a reactive circuit element (e.g., an inductor) may be included in impedance 202. Although in Figure 2 Only a single impedance is depicted in FIG, but in other embodiments, any suitable number of impedances may be used.

[0035] Capacitor 203 is coupled between the output signal lines of amplifier circuit 201. In various embodiments, capacitor 203 may be part of an impedance matching network of amplifier circuit 201, or a passive filter circuit at the output of amplifier circuit 201. Figure 2 Only a single capacitor is shown in the embodiment of FIG. 1 , but in other embodiments, any suitable number of capacitors may be used.

[0036] In some embodiments, both impedance 202 and capacitor 203 may be fabricated on the same integrated circuit as amplifier circuit 201 and mixer circuit 204. In other embodiments, impedance 202 and capacitor 203 may be fabricated on a different integrated circuit than amplifier circuit 201 and mixer circuit 204. In some cases, impedance 202 and capacitor 203 may be discrete devices coupled to an integrated circuit that includes amplifier circuit 201 and mixer circuit 204.

[0037] In some cases, antenna 104 may not be sufficiently isolated from antenna 103. When this occurs, antenna 104 may directly receive transmit signal 108 in a process commonly referred to as "leakage" without any reflection from a target or other object. In such cases, the signal received by antenna 104 is a composite signal of transmit signal 108 and echo signal 109. Such transmit leakage may appear as a DC of a low frequency tone at the input of filter circuit 105. In some cases, a low noise amplifier and mixer circuit may process this tone, which is removed in baseband using AC coupling. Using such coupling may cause the low noise amplifier and mixer circuit to operate at a lower gain with reduced sensitivity.

[0038] A modification of the filter circuit 200 that employs a servo-based offset cancellation loop can be used to remove the tones generated by leakage. Figure 3 A block diagram of such a modified filter circuit is shown in As shown, the filter circuit 300 includes an amplifier circuit 301 , an impedance 302 , a capacitor 303 , a mixer circuit 305 , and a feedback circuit 309 .

[0039] The amplifier circuit 301 and the mixer circuit 305 are configured to Figure 2 The amplifier circuit 201 and the mixer circuit 204 shown in FIG. 2 operate in a similar manner. In addition, the impedance 302 and the capacitor 303 are configured to perform the same as shown in FIG. Figure 2 Impedance 202 and capacitor 203 are depicted to function similarly. Note that in other embodiments, the combination of amplifier circuit 301, impedance 302, and capacitor 303 may employ any suitable number of amplifier circuits, impedances, and capacitors.

[0040] Feedback circuit 309 includes variable impedance circuit 306 and amplifier circuit 304. Variable impedance circuit 306 is configured to filter frequency components of output signal 111 outside a frequency band centered on a specific frequency to generate feedback signal 308. Amplifier circuit 304 is configured to amplify feedback signal 308, which is combined with intermediate signal 307 at the input of amplifier circuit 301. In various embodiments, the specific frequency may be at or near a DC frequency level. The width of the frequency band may be based on characteristics of sensor circuit 100, including but not limited to parasitic circuit elements within sensor circuit 100, leakage of transmit signal 108 to antenna 104, etc.

[0041] The variable impedance circuit 306 may be designed according to one of a variety of design styles to provide different gains in different frequency bands. For example, the variable impedance circuit 306 may be configured to provide a gain > 1 for signals in a frequency band around a specific frequency, and to provide a gain < 1 for signals whose frequencies are outside the frequency band. In some cases, the variable impedance circuit 306 may include a resonator circuit that is configured to resonate at a specific frequency, thereby providing a low impedance in a frequency band around the specific frequency, and filtering the output signal 111 outside the frequency band. Such a resonator circuit may include any suitable combination of inductors, capacitors, and other suitable circuit elements.

[0042] Alternatively, variable impedance circuit 306 may be a specific implementation of an integrator circuit that is configured to generate feedback signal 308 such that the magnitude of feedback signal 308 is proportional to the voltage level of output signal 111 integrated over time. In some cases, the transfer function of such an integrator circuit is given by Equation 1 (in the Laplace domain), where ω μ is the angular frequency of the integrator circuit.

[0043]

[0044] In various embodiments, the integrator circuit may include any suitable combination of operational amplifiers and passive circuit elements (such as resistors and capacitors) to perform the integration function. Note that while variable impedance circuit 306 and amplifier circuit 304 are depicted as separate components in feedback circuit 309, in other embodiments, amplifier circuit 304 and variable impedance circuit 306 may be combined into a single component that filters certain frequencies and then amplifies the feedback signal.

[0045] Amplifier circuit 304 is coupled to the output of variable impedance circuit 306 and the input of amplifier circuit 301, and is configured to amplify feedback signal 308. The output of amplifier circuit 304 is added to intermediate signal 307 at the input of amplifier circuit 301, thereby forming a feedback loop with output signal 111. Amplifier circuit 304 can be a specific implementation of a differential amplifier and can include multiple transconductance elements or other gain devices. For example, amplifier circuit 301 can include MOSFETs, bipolar transistors, or other devices compatible with any other suitable semiconductor manufacturing process used to manufacture sensor circuit 100.

[0046] The feedback provided by feedback circuit 309 independently cancels the offset on the in-phase (I) channel and the quadrature (Q) channel of the receiver path of sensor circuit 100. Due to the transparent nature of mixer circuit 305, once the offset due to leakage is cancelled in baseband, it is up-converted at RF and directly suppressed at antenna 104 before reaching mixer circuit 305, thereby creating a high-Q bandpass filter with a center frequency notch at antenna 104. Therefore, amplifier circuit 301 and mixer circuit 305 can operate at maximum gain.

[0047] Please note that Figure 3 In the illustrated embodiment, variable impedance circuit 306 is coupled to output signal 111 and uses output signal 111 to generate feedback signal 308. In other embodiments, variable impedance circuit 306 may use as input a data bit stream indicative of output signal 111. For example, the input of the variable impedance circuit may be coupled to output data bit 405, transformed data bit 406 (e.g., Figure 4 ), or any other suitable data bit derived from the output signal 111. Where the variable impedance circuit 306 uses a data bit stream as input, the variable impedance circuit 306 may include a digital-to-analog converter circuit or other suitable circuitry configured to convert the data bit stream into analog voltage levels.

[0048] exist Figure 4 4 is a block diagram of an embodiment of the control circuit 106. As shown, the control circuit 106 includes a digital-to-analog converter circuit 401, an analog-to-digital converter circuit 402, and a fast Fourier transform circuit 403.

[0049] The digital-to-analog converter circuit 401 is configured to generate the baseband signal 107 using the input data bits 404. In various embodiments, the value of the input data bits 404 at a particular point in time may be used to determine the voltage level of the baseband signal 107 at a particular point in time. In other words, the digital-to-analog converter circuit 401 converts the time series of data bits into a continuously varying analog signal. In various embodiments, the digital-to-analog converter circuit 401 may include a current source or a voltage source, and a plurality of switches configured to selectively couple the current source or the voltage source to a circuit node over which the baseband signal 107 propagates.

[0050] The analog-to-digital converter circuit 402 is configured to generate output data bits 405 using the output signal 111. In various embodiments, the analog-to-digital converter circuit 402 samples the voltage level of the output signal 111 and generates a subset of the output data bits 405, the magnitude of which is proportional to the magnitude of the voltage level of the output signal 111 when it is sampled. The analog-to-digital converter circuit can sample the voltage level of the output signal 111 at any suitable frequency to detect changes in the voltage level of the output signal 111. The analog-to-digital converter circuit 402 can be designed according to one of a variety of design styles. For example, the analog-to-digital converter circuit 402 may include a plurality of comparators configured to compare the voltage level of the output signal 111 with a corresponding voltage reference level at a particular sampling point in order to generate a subset of the output data bits 405.

[0051] Fast Fourier transform circuit 403 is configured to perform discrete Fourier transform to output data bit 405 to convert data from time domain data to frequency domain data. In various embodiments, frequency domain data can be encoded in transform data bit 406, which can be used by other processing circuits (not shown) for further processing. As described in more detail below, the frequency of output signal 111 is proportional to the range of the target or object that generates echo signal 109 by reflecting transmission signal 108. By converting output data bit 405 into frequency domain, fast Fourier transform circuit 403 generates data indicating the distance from target or object. In some embodiments, fast Fourier transform circuit 403 can be a special logic circuit, which has multiple logic gates, latches, trigger circuits, etc. Such logic gates, latches, etc. can be arranged to realize desired conversion. Alternatively, fast Fourier transform circuit 403 can be a specific embodiment of a general-purpose processor, which is configured to perform desired conversion in response to executing program instructions.

[0052] To further illustrate how the sensor circuit 100 can determine the distance to an object or target, Figure 5 1 and 2. Exemplary waveforms of a transmit signal 108 and an echo signal 109 are depicted in FIG. As shown, the sensor circuit 100 sends out a transmit signal 108, which is reflected from a target 500 to generate an echo signal 109. The sensor circuit 100 is positioned at a distance 501 from the target 500.

[0053] Since the transmit signal 108 is modulated by the modulation signal 110, the frequency of the transmit signal 108 varies with time, as shown in the graph 502. For example, at time t1, the frequency of the transmit signal 108 is f1, and at time t2, the frequency of the transmit signal 108 is f2.

[0054] The frequency change of the transmit signal 108 from its minimum frequency value to its maximum frequency value is given by ΔF. The period during which the transmit signal 108 transitions from its minimum frequency value to its maximum frequency value and back to its minimum frequency value is given by T chirp express.

[0055] As described above, the echo signal 109 is a reflected version of the transmit signal 108. The echo signal 109 is delayed by Δt from the transmit signal 108 due to the travel time from the sensor circuit 100 to the target 500 and then back to the sensor circuit 100. By knowing Δt and the speed at which the transmit signal 108 and the echo signal 109 propagate (e.g., the speed of light), the value of the distance 501 can be determined.

[0056] Rather than attempting to determine the delay in receiving the echo signal 109, once the echo signal 109 has been down-converted and filtered, the distance 501 may be determined based on the baseband frequency of the echo signal. As described above, the control circuit 106 may use a discrete Fourier transform to convert the down-converted version of the echo signal 109 from the time domain into the frequency domain, thereby determining the baseband frequency. The distance 501 may then be determined using Equation 2, where f BB is the baseband frequency, ΔF is the difference between the maximum frequency value and the minimum frequency value of the transmission signal 108, T chirp is the period of the modulation signal 110, r target is the distance to the target (i.e., distance 501), and c is the speed of light. In various embodiments, control circuit 106 may determine f BB , and another circuit (e.g., a processor) may perform calculations to determine r target , while in other embodiments, once f has been determined BB , the control circuit 106 can also determine r target .

[0057]

[0058] Go to Figure 6 , shows an example of a transfer function associated with the filter circuit 200. In various embodiments, time points t1 and t2 may correspond to Figure 5 Time points indicated.

[0059] The transfer function of the filter circuit 200 is shown for two different frequencies, each frequency corresponding to the frequency of the transmit signal 108 at a particular point in time. For example, at time t1, f tx (t1) may be substantially 1 GHz, and at time t2, f tx (t2) may be substantially 1.5 GHz. Therefore, frequency range 601 will have a value of approximately 0.5 GHz. For clarity, Figure 6Only two time points with corresponding two frequencies are described in . Other time points will produce additional transfer functions similar to those shown, but centered at different frequencies corresponding to the other time points.

[0060] At frequency f tx At (t1), the transfer function of the filter circuit 200 indicates that the filter circuit 200 is tx (t1) is the center of the frequency band and attenuates the frequencies outside the band, and at the frequency f tx At (t2), the transfer function of the filter circuit 200 indicates that the filter circuit 200 is tx (t2) is the center frequency band and attenuates frequencies outside the frequency band. In various embodiments, the width of the frequency band may correspond to 5 MHz or any other suitable value. As described above, the center frequency of the filter circuit 200 tracks the carrier frequency of the transmit signal 108, thereby eliminating the need for an amplifier circuit that must provide sufficient gain within the frequency range associated with the transmit signal 108.

[0061] Go to Figure 7 , shows an exemplary waveform of the transfer function of the exemplary filter circuit 300. In various embodiments, the time points t1 and t2 may correspond to Figure 5 Time points indicated.

[0062] As shown, exemplary waveforms of the transfer function of the filter circuit 300 are depicted for two points in time. Figure 6 As with the transfer function depicted, additional time points will show the same basic waveform occurring at different frequencies within the possible frequency range of the transmit signal 108 .

[0063] As described above, the use of integrator circuit 306 produces notches 701 and 702 in the two transfer function responses. Each of notches 701 and 702 is at the frequency of transmit signal 108 at a corresponding point in time. The notches indicate that filter circuit 300 is at f tx (t1) and f tx (t2) has very little gain, resulting in attenuation of the frequency of the transmit signal 108. By attenuating the frequency of the transmit signal 108 as a function of time, leakage from antenna 103 to antenna 104 and its contribution from the ranging calculation is eliminated.

[0064] Go to Figure 8 , a flow chart depicting an embodiment of a method for operating a sensor circuit is shown. The method starting in block 801 may be applied to sensor circuit 100 or any other suitable sensor circuit.

[0065] The method includes generating a baseband signal (block 802). In some embodiments, the method may also include generating the baseband signal using a first plurality of data bits and a digital-to-analog converter circuit. The method also includes transmitting a transmit signal using a first antenna (block 803). In various embodiments, the transmit signal may be a modulated version of the baseband signal. In some embodiments, the method may include modulating the baseband signal using a modulating signal to generate the transmit signal.

[0066] The method also includes receiving an echo signal generated by reflection of the transmit signal by the object using a second antenna included in the sensor circuit (block 804). As described above, for a particular point in time, the frequency of the echo signal may be different from the frequency of the transmit signal.

[0067] The method also includes filtering the echo signal using a filter that tracks the carrier frequency of the echo signal to generate an output signal (block 805). In various embodiments, filtering the echo signal includes down-converting the echo signal using a second mixer circuit to generate an intermediate signal. As described above, down-converting the echo signal includes using the echo signal and the modulation signal to generate a new signal, i.e., the intermediate signal. In some cases, the frequency of the intermediate signal is the difference between the frequency of the echo signal and the frequency of the modulation signal.

[0068] In some cases, the method includes amplifying the intermediate signal to generate an output signal. In various embodiments, the method may include converting the output signal into a plurality of data bits using an analog-to-digital converter, and using the first plurality of data bits to determine a distance from an object that reflected the transmit signal to create an echo signal. To determine the distance, the method may include performing a fast Fourier transform algorithm on the plurality of data bits.

[0069] In some embodiments, filtering the echo signal includes suppressing at least one frequency component of the echo signal generated by the second antenna receiving the transmit signal directly from the first antenna. As described above, the proximity of the first antenna and the second antenna may result in the second antenna receiving the transmit signal directly from the first antenna. This may result in an incorrect calculation of the distance to the object responsible for generating the echo signal.

[0070] The method also includes using the output signal by the sensor circuit to determine information indicating the distance from the sensor circuit to the object (block 806). In some cases, the method also includes using the information by the processor circuit to determine a value of the distance to the object. The method ends in block 807.

[0071] Go to Fig. 9 , a flow chart depicting an embodiment of another method for operating a sensor circuit is shown. The method starting in block 901 may be applied to sensor circuit 100 or any other suitable sensor circuit.

[0072] The method includes generating a baseband signal (block 902). As described above, the method may include using a digital-to-analog converter circuit to generate the baseband signal based on a first plurality of data bits. The method also includes using a first antenna to transmit a transmit signal (block 903). In various embodiments, the transmit signal may be a modulated version of the baseband signal. As described above, a mixer circuit may be used to modulate the baseband signal to generate the transmit signal.

[0073] The method also includes receiving the echo signal using the second antenna (block 904). Once the echo signal has been received, the method includes filtering the echo signal to suppress at least one frequency component of the echo signal. In various embodiments, the at least one frequency component is generated by the second antenna receiving the transmit signal directly from the first antenna. By filtering the at least one frequency component, the distance to the object reflecting the transmit signal can be improved to generate the echo signal. The method ends in block 905.

[0074] exist Fig.10 1000. As shown, computer system 1000 includes analog / mixed signal circuitry 1001, processor circuitry 1002, memory circuitry 1003, and input / output circuitry 1004, each of which is coupled to a communication bus 1005. In various embodiments, computer system 1000 may be a system on a chip (SoC) and may be configured for use in a desktop computer, a server, or in a mobile computing application such as a tablet, a laptop, or a wearable computing device.

[0075] The analog / mixed signal circuit 1001 includes various circuits with the sensor circuit 100. In addition, the analog / mixed signal circuit 1001 may include a crystal oscillator circuit, a phase-locked loop (PLL) circuit, an analog-to-digital converter (ADC) circuit, and a digital-to-analog converter (DAC) circuit (all not shown). In other embodiments, the analog / mixed signal circuit 1001 may be configured to perform power management tasks by including an on-chip power supply and regulator.

[0076] In various embodiments, processor circuit 1002 may represent a general purpose processor that performs computing operations. For example, processor circuit 1002 may be a central processing unit (CPU) such as a microprocessor, microcontroller, application specific integrated circuit (ASIC), or field programmable gate array (FPGA).

[0077] In various embodiments, memory circuit 1003 may include any suitable type of memory, such as, for example, dynamic random access memory (DRAM), static random access memory (SRAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), or non-volatile memory. Fig.10In the embodiment of the computer system in , a single memory circuit is depicted. In other embodiments, any suitable number of memories may be used.

[0078] Input / output circuitry 1004 may be configured to coordinate data transfers between computer system 1000 and one or more peripheral devices. Such peripheral devices may include, but are not limited to, storage devices (e.g., storage devices based on magnetic or optical media, including hard drives, tape drives, CD drives, DVD drives, etc.), audio processing subsystems, or any other suitable type of peripheral device. In some embodiments, input / output circuitry 1004 may be configured to implement the Universal Serial Bus (USB) protocol or IEEE 1394. The version of the protocol.

[0079] The input / output circuitry 1004 may also be configured to coordinate data transfers between the computer system 1000 and one or more devices (e.g., other computing systems or integrated circuits) coupled to the computer system 1000 via a network. In one embodiment, the input / output circuitry 604 may be configured to perform the data processing necessary to implement an Ethernet (IEEE 802.3) networking standard such as, for example, Gigabit Ethernet or 10 Gigabit Ethernet, but it is contemplated that any suitable networking standard may be implemented. In some embodiments, the input / output circuitry 1004 may be configured to implement multiple discrete network interface ports.

[0080] Although specific embodiments have been described above, these embodiments are not intended to limit the scope of the present disclosure, even when only a single embodiment is described with respect to specific features. The feature examples provided in this disclosure are intended to be illustrative, not limiting, unless otherwise stated. The above description is intended to cover such alternatives, modifications, and equivalents, which will be apparent to those skilled in the art who are aware of the effective effects of the present disclosure.

[0081] The scope of the present disclosure includes any feature or combination of features disclosed herein (explicitly or implicitly) or any generalization thereof, whether or not it mitigates any or all of the problems addressed herein. Accordingly, new claims may be made during the prosecution of this patent application (or a patent application claiming priority thereto) for any such combination of features. In particular, with reference to the appended claims, features of the dependent claims may be combined with features of the independent claims, and features from the corresponding independent claims may be combined in any appropriate manner and not just by the specific combinations listed in the appended claims.

Claims

1. A device for generating an output signal, comprising: a first antenna and a second antenna; a control circuit configured to generate a baseband signal; a transmitter circuit, the transmitter circuit being configured to transmit a transmission signal via the first antenna, the transmission signal being generated by modulating the baseband signal by a modulation signal; as well as A filter circuit, the filter circuit comprising: a mixer circuit coupled to the second antenna, wherein the mixer circuit is configured to down-convert an echo signal received by the second antenna using the modulated signal to generate an intermediate signal; as well as an amplifier circuit configured to amplify the intermediate signal to generate an output signal, and Wherein the echo signal is a reflected version of the transmit signal.

2. The apparatus of claim 1 , wherein the filter circuit further comprises an impedance matching network coupled between output nodes of the amplifier circuit, wherein the impedance matching network is configured to match an output impedance of the amplifier circuit to an input impedance of the control circuit.

3. The apparatus according to claim 2, wherein the control circuit is further configured to: generating a plurality of data bits using the output signal; and Information indicative of a distance to an object that reflected the transmit signal is determined using the plurality of data bits to create the echo signal. 4 . The apparatus of claim 2 , wherein the filter circuit is further configured to suppress at least one frequency component of the echo signal generated by directly receiving the transmit signal from the first antenna through the second antenna.

5. The apparatus of claim 4, wherein the filter circuit further comprises: a variable impedance circuit configured to attenuate one or more frequency components of the output signal to generate a feedback signal, wherein: The one or more frequency components are outside a frequency band centered around a specific frequency, and The amplitude of the feedback signal is proportional to the voltage level of the output signal integrated over time; and A second amplifier circuit is configured to amplify the feedback signal and combine the amplified version of the feedback signal with the intermediate signal. 6 . The apparatus of claim 1 , wherein the control circuit is further configured to determine information indicating a distance to an object that reflected the transmit signal to generate the echo signal using a plurality of data bits generated based on the output signal.

7. The apparatus of claim 1, wherein the filter circuit comprises a narrowband filter.

8. A method for generating an output signal, comprising: generating a baseband signal by the sensor circuit; The sensor circuit uses a first antenna to transmit a transmission signal, wherein the transmission signal is generated by modulating the baseband signal by a modulation signal; receiving, using a second antenna included in the sensor circuit, an echo signal generated by reflection of the transmit signal from an object; down-converting the echo signal using the modulated signal to generate an intermediate signal by a mixer circuit included in the sensor circuit, wherein the mixer circuit is coupled to the second antenna; as well as amplifying the intermediate signal by an amplifier circuit of the sensor circuit to generate an output signal; as well as The output signal is used by the sensor circuit to determine information indicative of a distance from the sensor circuit to the object. 9 . The method of claim 8 , further comprising filtering the output signal by a variable impedance circuit of the sensor circuit to generate a feedback signal.

10. The method of claim 8, wherein determining the information indicative of the distance to the object comprises converting the output signal into a first plurality of data bits using an analog-to-digital converter. The method of claim 10 , further comprising using the first plurality of data bits to determine the distance to the object. 12 . The method of claim 10 , wherein down-converting the echo signal comprises suppressing at least one frequency component of the echo signal generated by directly receiving the transmit signal from the first antenna through the second antenna.

13. The method of claim 12, wherein suppressing the at least one frequency component of the echo signal comprises filtering one or more frequency components of the output signal to generate a feedback signal, and combining the feedback signal with the intermediate signal.

14. The method of claim 8, further comprising generating the baseband signal using a second plurality of data bits and a digital-to-analog converter circuit.

15. An apparatus for generating an output signal, comprising: a control circuit configured to generate a baseband signal; a transmitter circuit, the transmitter circuit being configured to transmit a transmission signal via a first antenna, the transmission signal being generated by modulating the baseband signal by a modulation signal; a first mixer circuit coupled to the second antenna, wherein the first mixer circuit is configured to down-convert the echo signal using the modulated signal to generate an intermediate signal; as well as An amplifier circuit, the amplifier circuit being configured to: amplifying the intermediate signal to generate an output signal; and The intermediate signal is modified using a version of the output signal that is filtered outside of a frequency band centered around a particular frequency.

16. The apparatus of claim 15, wherein the control circuit is further configured to generate the baseband signal using a first plurality of data bits. 17 . The apparatus of claim 15 , further comprising a second mixer circuit configured to modulate the baseband signal using the modulation signal to generate the transmit signal.

18. The apparatus of claim 17, wherein the first mixer circuit is further configured to combine the echo signal with the modulation signal to generate the intermediate signal.

19. The apparatus of claim 15, wherein the control circuit comprises an analog-to-digital converter circuit configured to generate a second plurality of data bits using the output signal.

20. The apparatus of claim 19, wherein the control circuit is further configured to use the second plurality of data bits to determine information indicative of a distance to an object that reflected the transmit signal to create the echo signal.

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