Wireless phased array receiver using low resolution analog-to-digital converters

The present application is related to U.S. patent application Ser. No. 15/225,071, filed on Aug. 1, 2016, and titled “Wireless Receiver with Axial Ratio and Cross-Polarization Calibration,” and U.S. patent application Ser. No. 15/225,523, filed on Aug. 1, 2016, and titled “Wireless Receiver with Tracking Using Location, Heading, and Motion Sensors and Adaptive Power Detection.” The disclosures of these related applications are hereby incorporated fully by reference into the present application.

A wireless phased array receiver consisting of multiple receiving antennas provides several benefits such as signal to noise ratio (“SNR”) improvement, beam steering, spatial filtering and interference rejection. Phased arrays can be implemented in several architectures including but not limited to radio frequency (“RF”) beamforming, intermediate frequency (“IF”) beamforming and digital beamforming. The digital beamforming (“DBF”) architecture provides various advantages over other phased array architectures. The DBF is generally a more flexible and scalable beamforming architecture compared with, for example, RF beamforming and IF beamforming architectures. Further, by eliminating the need for several analog phase shifting and combining paths per antenna, DBF is a very suitable architecture for phased array systems with multiple beams. One impediment for implementing the DBF, in particular for larger phased arrays (those with more than 10 antennas), has been the prohibitive total power consumption of a large number of analog-to-digital (“A/D”) converters. This is because in DBF, unlike other phased array architectures, one A/D is required per antenna. Thus, there is need in the art to overcome impediments in implementing digital beamforming in large phased array receivers and to enable an advantageous DBF architecture for large phased arrays.

The present disclosure is directed to wireless phased array receivers using low resolution analog-to-digital (A/D) converters, substantially as shown in and/or described in connection with at least one of the figures, and as set forth in the claims.

FIG. 1 illustrates a top plan view of a portion of an antenna phased array panel of an exemplary wireless receiver according to one implementation of the present application.

FIG. 2A illustrates a functional block diagram of a portion of an exemplary wireless receiver according to one implementation of the present application.

FIG. 2B illustrates a functional block diagram of an exemplary low resolution analog-to-digital converter according to one implementation of the present application.

FIG. 2C illustrates an exemplary input-output waveform of a low resolution analog-to-digital converter according to one implementation of the present implementation.

FIG. 2D illustrates diagrams of analog inputs in comparison with a reference value of a low resolution analog-to-digital converter according to one implementation of the present implementation.

FIG. 3 illustrates a functional block diagram of a portion of an exemplary wireless receiver according to one implementation of the present application.

The following description contains specific information pertaining to implementations in the present disclosure. The drawings in the present application and their accompanying detailed description are directed to merely exemplary implementations. Unless noted otherwise, like or corresponding elements among the figures may be indicated by like or corresponding reference numerals. Moreover, the drawings and illustrations in the present application are generally not to scale, and are not intended to correspond to actual relative dimensions.

Referring to FIG. 1 , FIG. 1 illustrates a top plan view of a portion of a phased array antenna panel (also referred to simply as an “antenna panel” herein) of an exemplary wireless receiver according to one implementation of the present application. As illustrated in FIG. 1 , antenna panel 101 includes a plurality of antennas, e.g., antennas 102 a through 102 n , collectively referred to as antennas 102 . In one implementation, antennas 102 may be configured to receive signals from one or more wireless transmitters, such as commercial geostationary communication satellites or low earth orbit satellites having a very large bandwidth in the 10 GHz to 20 GHz frequency range and a very high data rate. In another implementation, antennas 102 may be configured to receive signals in the 60 GHz frequency range, sometimes referred to as “60 GHz communications,” which involve transmission and reception of millimeter wave signals. Among the applications for 60 GHz communications are wireless personal area networks, wireless high-definition television signal and Point-to-Point links.

In one implementation, for a wireless transmitter transmitting signals at 10 GHz (i.e., λ=30 mm), each antenna in antenna panel 101 in a wireless receiver needs an area of at least a quarter wavelength (e.g., λ/4=7.5 mm) by a quarter wavelength (e.g., λ/4=7.5 mm) to receive the transmitted signals. As illustrated in FIG. 1 , antennas 102 in antenna panel 101 may each have a square shape having dimensions of 7.5 mm by 7.5 mm, for example. In one implementation, each adjacent pair of antennas 102 may be separated by a distance of a multiple integer of the quarter wavelength (i.e., n*λ/4), such as 7.5 mm, 15 mm, 22.5 mm, and etc. As illustrated in FIG. 1 , antenna panel 101 includes a total of N spatially separated antennas 102 . In one implementation, the number of antennas 102 can be as small as 2. In another implementation, the number of antennas 102 can be as large as several thousands (e.g., N=2000). In general, the performance of the wireless receiver improves with the number, N, of antennas 102 in antenna panel 101 .

In the present implementation, antenna panel 101 is a flat panel array employing antennas 102 , where antenna panel 101 is coupled to associated active circuits to form a beam for reception and/or transmission. In one implementation, the beam is formed fully electronically by means of phase and amplitude control circuits associated with antennas 102 . Thus, antenna panel 101 can provide for beamforming without the use of any mechanical parts.

Referring to FIG. 2A , FIG. 2A illustrates a functional block diagram of a portion of an exemplary wireless receiver according to one implementation of the present application. As illustrated in FIG. 2A , wireless receiver 200 includes antennas 202 a through 202 n , each coupled to digital beamforming block 212 through paths 1 through n, respectively. In the present implementation, antennas 202 a through 202 n in FIG. 2A may correspond to antennas 102 a through 102 n , respectively, in antenna panel 101 shown in FIG. 1 . In the present implementation, each of antennas 202 a through 202 n may receive one or more signals from wireless transmitter 298 , such as a commercial geostationary communication satellites or a low earth orbit satellite.

In one implementation, wireless transmitter 298 may employ linearly-polarized or circularly polarized signals, such as single or dual linearly-polarized signals. As illustrated in FIG. 2A , low resolution A/D converters 210 a through 210 n are coupled to respective antennas 202 a through 202 n , where low resolution A/D converters 210 a through 210 n are configured to provide digital outputs 211 a through 211 n , respectively, to digital beamforming block 212 . In the present implementation, low resolution A/D converters 210 a through 210 n comprise one-bit A/D converters, such as a single comparator, for example a complementary metal-oxide-semiconductor (CMOS) comparator. In other implementations, low resolution A/D converters 210 a through 210 n comprise two-bit or three-bit A/D converters. Digital beamforming block 212 includes n parallel paths for receiving respective digital outputs 211 a through 211 n , and provides combined signal S combined for further signal processing.

In the example presented by FIG. 2A , antennas 202 a through 202 n are single feed antennas for receiving single linear-polarized signals, such as a horizontally-polarized (H) signal having its electric-field oriented parallel with the equatorial plane or a vertically-polarized (V) signal having its electric-field oriented perpendicular to the equatorial plane. As illustrated in FIG. 2A , signal S 1 received by each of antennas 202 a through 202 n is accompanied by uncorrelated noises N 1 through Nn, respectively. For example, antenna 202 a receives signal S 1 from wireless transmitter 298 , where signal S 1 is accompanied by noise N 1 . Signal S 1 and noise N 1 are provided to LNA 204 a , which is configured to generate an amplified output to mixer 206 a . Mixer 206 a and local oscillator 208 a are configured to downconvert the frequency of the amplified output from LNA 204 a , for example, from radio frequency to intermediate frequency. Mixer 206 a then provides downconverted analog input 209 a to low resolution A/D converter 210 a . Low resolution A/D converter 210 a converts analog input 209 a to digital output 211 a , and provides digital output 211 a to digital beamforming block 212 for digital beamforming.

Similarly, antenna 202 n receives signal S 1 from wireless transmitter 298 , where signal S 1 is accompanied by noise Nn. Signal S 1 and noise Nn are provided to LNA 204 n , which is configured to generate an amplified output to mixer 206 n . Mixer 206 n and local oscillator 208 n are configured to downconvert the frequency of the amplified output from LNA 204 n , for example, from radio frequency to intermediate frequency. Mixer 206 n then provides downconverted analog input 209 n to low resolution A/D converter 210 n . Low resolution A/D converter 210 n converts analog input 209 n to digital output 211 n , and provides digital output 211 n to digital beamforming block 212 for digital beamforming.

It should be noted that, although FIG. 2A shows antennas 202 a through 202 n as single feed antennas, in another implementation, antennas 202 a through 202 n may be dual feed antennas with dual polarization feeds for a horizontally-polarized (H) signal and a vertically-polarized (V) signal. In that case, a signal accompanied by a noise received at each antenna and provided at each polarization feed passes through a separate LNA, mixer and A/D converter for each polarization.

Referring to FIG. 2B , FIG. 2B illustrates a functional block diagram of an exemplary low resolution analog-to-digital converter according to one implementation of the present application. In one implementation, low resolution A/D converter 210 may correspond to any of low resolution A/D converters 210 a through 210 n in wireless receiver 200 shown in FIG. 2A . As illustrated in FIG. 2B , low resolution A/D converter 210 receives analog input 209 (Vin) and a reference signal having reference value 205 (Vret) as inputs, and provides digital output 211 (Vout) to, for example, a digital beamforming block for digital beamforming. As an example, analog input 209 (Vin) may correspond to analog input 209 a received from antenna 202 a in FIG. 2A . Low resolution A/D converter 210 may correspond to low resolution A/D converter 210 a in FIG. 2A . Low resolution A/D converter 210 is configured to provide digital output 211 , for example, based on comparing reference value 205 (Vref) with the sum of signal S 1 and noise N 1 of analog input 209 a (Vin) received from antenna 202 a in FIG. 2A .

In the present implementation, low resolution A/D converter 210 comprises a one-bit A/D converter, such as a single comparator. In one implementation, low resolution A/D converter 210 comprises a complementary metal-oxide-semiconductor (CMOS) comparator. In another implementation, low resolution A/D converter 210 may be a two-bit or three-bit A/D converter.

Referring to FIG. 2C , FIG. 2C illustrates an exemplary input-output waveform of a low resolution A/D converter according to one implementation of the present implementation. In the present implementation, a low resolution A/D converter compares an analog input (Vin) to a reference value (Vref), and provides a digital output (Vout). As illustrated in waveform 280 , the low resolution A/D converter, such as low resolution A/D converter 210 in FIG. 2B , generates a “+1” output for analog input (Vin) voltages between approximately Vref and +Vmax. The low resolution A/D converter generates a “−1” output for analog input (Vin) voltages between −Vmax and approximately Vref. In one implementation, the low resolution A/D converter generates a “0” output (instead of a “−1” output) for analog input (Vin) voltages between −Vmax and approximately Vref. It should be understood that the low-resolution A/D converter may have metastability region 282 where the digital outputs may be subject to small disturbances of the analog inputs and the A/D converter itself. In one implementation, metastability region 282 may have width 288 of approximately 1 to 3 mV (10^-3 Volts), for example.

Referring to FIG. 2D , FIG. 2D illustrates diagrams of analog inputs in comparison with a reference value of a low resolution A/D converter, for example low resolution A/D converter 210 comprising a one-bit A/D converter, such as a single comparator, as shown in FIG. 2B , according to one implementation of the present application. As shown in FIG. 2D , diagram 230 A illustrates analog inputs 209 a , 209 b , 209 c , 209 d , 209 e , 209 f . . . 209 n (collectively referred to as analog inputs 209 a through 209 n ) received from respective antennas 202 a through 202 n of an antenna panel of a wireless receiver. In the present implementation, analog inputs 209 a through 209 n in diagram 230 A may correspond to analog inputs 209 a through 209 n in FIG. 2A and/or analog input 209 in FIG. 2B . In the present implementation, reference value 205 (Vref) and metastability region 282 may correspond to reference value 205 (Vref) and metastability region 282 , respectively, in FIGS. 2B and 2C . It should be noted that, in the present implementation, as shown in diagram 230 A, each of analog inputs 209 a through 209 n may be substantially equal to the sum of signal S 1 and the correspond noise received at each of antennas 202 a through 202 n , respectively. For example, analog input 209 a may be substantially equal to the sum of signal S 1 and noise N 1 received from antenna 202 a in FIG. 2A . Similarly, analog input 209 n may be substantially equal to the sum of signal S 1 and noise Nn received from antenna 202 n in FIG. 2A .

In the example shown in diagram 230 A, the voltage level of signal S 1 received at each antenna 202 a through 202 n is substantially below reference value 205 (Vref), which means that, without taking into account the corresponding noise levels accompanying signal S 1 at each antenna, none of signal S 1 values received from antennas 202 a through 202 n would be able to result in a “+1” output from the corresponding converter. In a conventional high resolution A/D converter, such a low signal level would require one or more variable gain amplifiers and feedback loops to amplify the weak signal to a detectable level to trigger the comparators in the high resolution A/D converter, which would consume a significant amount of power and result in reduced conversion speed. According to the novel approach of the present implementation, however, the low resolution A/D converters, such as low resolution A/D converters 210 a through 210 n in FIG. 2A , are configured to compare an analog input, which is the sum of a signal value and a corresponding noise value, to a reference value that is selected based on the noise value, which is dominant over the signal value in the analog input. In other words, each low resolution A/D converter in the present implementation is triggered primarily by the presence of the dominant noise value as opposed to the signal value itself. It should be noted that, in the present implementation, noise N 1 through noise Nn received by antennas 202 a through 202 n , respectively, are uncorrelated, and further the SNR is low, and is generally less than one (negative in dB scale).

As illustrated in diagram 230 A, analog input 209 a includes signal S 1 and noise N 1 . While signal S 1 alone is substantially less than reference value 205 , the sum of noise N 1 and signal S 1 brings analog input 209 a above reference value 205 . As such, a corresponding low resolution A/D converter, such as low resolution A/D converter 210 a in wireless receiver 200 of FIG. 2A , would provide a “+1” output based on analog input 209 a dominated by noise N 1 . For analog input 209 b having signal S 1 and noise N 2 , the sum of signal S 1 and noise N 2 is below reference value 205 . Thus, a corresponding low resolution A/D converter, for example, in wireless receiver 200 of FIG. 2A would provide a “−1” output (or a “0” output in some implementations) based on analog input 209 b . For analog input 209 c having signal S 1 and noise N 3 , the sum of signal S 1 and noise N 3 is below reference value 205 . Thus, a corresponding low resolution A/D converter, for example, in wireless receiver 200 of FIG. 2A would provide a “−1” output (or a “0” output in some implementations) based on analog input 209 c . For analog input 209 d having signal S 1 and noise N 4 , the sum of signal S 1 and noise N 4 is below reference value 205 . Thus, a corresponding low resolution A/D converter, for example, in wireless receiver 200 of FIG. 2A would provide a “−1” output (or a “0” output in some implementations) based on analog input 209 d . For analog input 209 e having signal S 1 and noise N 5 , the sum of noise N 5 and signal S 1 brings analog input 209 e above reference value 205 . As such, a corresponding low resolution A/D converter, for example, in wireless receiver 200 of FIG. 2A would provide a “+1” output based on analog input 209 e dominated by noise N 5 . For analog input 209 f having signal S 1 and noise N 6 , the sum of signal S 1 and noise N 6 is below reference value 205 . Thus, a corresponding A/D converter, for example, in wireless receiver 200 of FIG. 2A would provide a “−1” output (or a “0” output in some implementations) based on analog input 209 f . For analog input 209 n having signal S 1 and noise Nn, the sum of noise Nn and signal S 1 brings analog input 209 n above reference value 205 . As such, a corresponding low resolution A/D converter, such as low resolution A/D converter 210 n in wireless receiver 200 of FIG. 2A , would provide a “+1” output based on analog input 209 n dominated by noise Nn.

As shown in diagram 230 A, although signal S 1 is substantially below reference value 205 , because analog inputs 209 a , 209 e and 209 n are substantially dominated by noises N 1 , N 5 and Nn, respectively, each of the sum of signal S 1 and noise N 1 , the sum of signal S 1 and noise N 5 , and the sum of signal S 1 and noise Nn, exceeds reference value 205 . Thus, analog inputs 209 a , 209 e and 209 n each result in a corresponding low resolution A/D converter generating a “+1” output without the need for variable gain amplifiers and feedback loops. Thus, in the example shown in diagram 230 A, signal S 1 results in a “−1” output (or a “0” output in some implementations) generated by the four low resolution A/D converters 210 b , 210 c , 210 d , and 210 f , and a “+1” output generated by the three low resolution A/D converters 210 a , 210 e , and 210 n.

In the example shown in diagram 230 B of FIG. 2D , analog inputs 209 a ′, 209 b ′, 209 c ′, 209 d ′, 209 e ′, 209 f . . . 209 n ′ (collectively referred to as analog inputs 209 a ′ through 209 n ′) are received from respective antennas 202 a through 202 n of an antenna panel of a wireless receiver. In the present example, analog inputs 209 a ′ through 209 n ′ in diagram 230 B are based on a new signal S 1 ′ received at antennas 202 a through 202 n . For the purpose of illustration of the operation of low resolution A/D converters 210 a through 210 n , noise N 1 through Nn is assumed to be substantially equal to noise N 1 through Nn, respectively, for signal S 1 in diagram 230 A.

As shown in the example of diagram 230 B, signal S 1 ′ is slightly greater than signal S 1 . However, the voltage level of signal S 1 ′ is still substantially below reference value 205 (Vref), which means that, without taking into account the corresponding noise levels accompanying signal S 1 ′ at each antenna, none of signal S 1 ′ values received from antennas 202 a through 202 n would be able to result in a “+1” output from the corresponding A/D converter. According to the novel approach of the present implementation, the low resolution A/D converters, such as low resolution A/D converters 210 a through 210 n in FIG. 2A , are configured to compare the analog input, which is the sum of the signal value and the corresponding noise value, to the reference value that is selected based on the noise value, which is dominant over the signal value in the analog input. Thus, each low resolution A/D converter is triggered primarily by the presence of the dominant noise value as opposed to the signal value itself. It should be noted that, in the present implementation, noise N 1 through noise Nn received by antennas 202 a through 202 n , respectively, are uncorrelated, and further the SNR is low, and is generally less than one.

As illustrated in diagram 230 B, analog input 209 a ′ includes signal S 1 ′ and noise N 1 . While signal S 1 ′ alone is substantially less than reference value 205 , the sum of noise N 1 and signal S 1 ′ brings analog input 209 a ′ above reference value 205 . As such, a corresponding low resolution A/D converter, such as low resolution A/D converter 210 a in wireless receiver 200 of FIG. 2A , would provide a “+1” output based on analog input 209 a ′ dominated by noise N 1 . For analog input 209 b ′ having signal S 1 ′ and noise N 2 , while signal S 1 ′ alone is less than reference value 205 , the sum of noise N 2 and signal S 1 ′ brings analog input 209 b ′ above reference value 205 . Thus, a corresponding low resolution A/D converter in wireless receiver 200 of FIG. 2A would provide a “+1” output based on analog input 209 b ′ dominated by noise N 2 . For analog input 209 c ′ having signal S 1 ′ and noise N 3 , the sum of signal S 1 ′ and noise N 3 is below reference value 205 . Thus, a corresponding low resolution A/D converter, for example, in wireless receiver 200 of FIG. 2A would provide a “−1” output (or a “0” output in some implementations) based on analog input 209 c ′. For analog input 209 d ′ having signal S 1 ′ and noise N 4 , the sum of signal S 1 ′ and noise N 4 is below reference value 205 . Thus, a corresponding low resolution A/D converter, for example, in wireless receiver 200 of, FIG. 2A would provide a “−1” output (or a “0” output in some implementations) based on analog input 209 d ′. For analog input 209 e ′ having signal S 1 ′ and noise N 5 , the sum of noise N 5 and signal S 1 ′ brings analog input 209 e ′ above reference value 205 . As such, a corresponding low resolution A/D converter, for example, in wireless receiver 200 of FIG. 2A would provide a “+1” output based on analog input 209 e ′ dominated by noise N 5 . For analog input 209 f having signal S 1 ′ and noise N 6 , the sum of signal S 1 ′ and noise N 6 is below reference value 205 . Thus, a corresponding low resolution A/D converter, for example, in wireless receiver 200 of FIG. 2A would provide a “−1” output (or a “0” output in some implementations) based on analog input 209 f . For analog input 209 n ′ having signal S 1 ′ and noise Nn, the sum of noise Nn and signal S 1 ′ brings analog input 209 n ′ above reference value 205 . As such, a corresponding low resolution A/D converter, such as low resolution A/D converter 210 n in wireless receiver 200 of FIG. 2A , would provide a “+1” output based on analog input 209 n ′ dominated by noise Nn.

As shown in diagram 230 B, although signal S 1 ′ is substantially below reference value 205 , because analog inputs 209 a ′, 209 b ′, 209 e ′ and 209 n ′ are substantially dominated by noises N 1 , N 2 , N 5 and Nn, respectively, each of the sum of signal S 1 ′ and noise N 1 , the sum of signal S 1 ′ and noise N 2 , the sum of signal S 1 ′ and noise N 5 , and the sum of signal S 1 ′ and noise Nn, exceeds reference value 205 . Thus, analog inputs 209 a ′, 209 b ′, 209 e ′ and 209 n ′ each result in a corresponding low resolution A/D converter generating a “+1” output without the need for variable gain amplifiers and feedback loops. Thus, in the example shown in diagram 230 B, signal S 1 ′ results in a “−1” output (or a “0” output in some implementations) generated by the three low resolution A/D converters 210 c , 210 d , and 210 f , and a “+1” output generated by the four low resolution A/D converters 210 a , 210 b , 210 e , and 210 n . Thus, it can be seen from this example that when the outputs of the array of multiple low-resolution A/D converters (one-bit A/D converters in the form of comparators in this case) are aligned in time and combined together using the digital beamforming block, the combined output signal of the digital beamforming block will have a higher value for signal S 1 ′ compared to signal S 1 . This is because the noise values from different A/D paths 1 through n are random and are uncorrelated and when all paths 1 through n are combined, the signal (S 1 or S 1 ′ in these examples) will determine the number of comparators that generate a value of “+1”.

Thus, according to various implementations of the present application, since the low resolution A/D converters, for example low resolution A/D converter 210 of FIG. 2B comprising a one-bit A/D converter, such as a single comparator, are designed to trigger based on the sum of the noise values and the signal values of the analog inputs, in particular, when the noise values are substantially greater than the signal values (i.e., the SNR of the analog input is less than one), the low resolution A/D converters do not require programmable gain amplifiers and feedback loops, and thus substantially reduce power consumption, in addition to the power consumption saving provided by the low-resolution A/D converters themselves compared to their high-resolution counterparts.

FIG. 3 illustrates a functional block diagram of a portion of an exemplary wireless receiver according to one implementation of the present application. As illustrated in FIG. 3 , wireless receiver 300 includes antennas 302 a through 302 n , each coupled to digital beamforming block 312 through paths 1 through n, respectively. In the present implementation, antennas 302 a through 302 n in FIG. 3 may correspond to antennas 102 a through 102 n , respectively, in antenna panel 101 shown in FIG. 1 . In the present implementation, each of antennas 302 a through 302 n may receive one or more signals from each of wireless transmitters 398 a , 398 b and 398 c , such as commercial geostationary communication satellites or low earth orbit satellites. In one implementation, each of wireless transmitters 398 a , 398 b and 398 c may employ linearly-polarized signals, such as single or dual linearly-polarized signals. As illustrated in FIG. 3 , low resolution A/D converters 310 a through 310 n are coupled to respective antennas 302 a through 302 n , where low resolution A/D converters 310 a through 310 n are configured to provide digital outputs 311 a through 311 n , respectively, to digital beamforming block 312 . Digital beamforming block 312 includes n parallel paths for receiving respective digital outputs 311 a through 311 n , and provides combined signal S combined for further signal processing.

In the example of FIG. 3 , antennas 302 a through 302 n are single feed antennas for receiving single linear-polarized signals, such as a horizontally-polarized (H) signal having its electric-field oriented parallel with the equatorial plane or a vertically-polarized (V) signal having its electric-field oriented perpendicular to the equatorial plane. As illustrated in FIG. 3 , signal S 1 received by each of antennas 302 a through 302 n is accompanied by uncorrelated noises N 1 through Nn, respectively. For example, antenna 302 a receives signal S 1 from wireless transmitter 398 a , where signal S 1 is accompanied by noise N 1 . Signal S 1 and noise N 1 are provided to LNA 304 a , which is configured to generate an amplified output to mixer 306 a . Mixer 306 a and local oscillator 308 a are configured to downconvert the frequency of the amplified output from LNA 304 a , for example, from radio frequency to intermediate frequency. Mixer 306 a then provides downconverted analog input 309 a to low resolution A/D converter 310 a . Low resolution A/D converter 310 a converts analog input 309 a to digital output 311 a , and provides digital output 311 a to digital beamforming block 312 for digital beamforming. As shown in FIG. 3 , antenna 302 a also receives signal S 2 from wireless transmitter 398 b where signal S 2 is accompanied by noise N 1 . Antenna 302 a further receives signal S 3 from wireless transmitter 398 c where signal S 3 is accompanied by noise N 1 , and provides them to digital beamforming block 312 through path 1 for digital beamforming.

Similarly, antenna 302 n receives signal S 1 from wireless transmitter 398 a , where signal S 1 is accompanied by noise Nn. Signal S 1 and noise Nn are provided to LNA 304 n , which is configured to generate an amplified output to mixer 306 n . Mixer 306 n and local oscillator 308 n are configured to downconvert the frequency of the amplified output from LNA 304 n , for example, from radio frequency to intermediate frequency. Mixer 306 n then provides downconverted analog input 309 n to low resolution A/D converter 310 n . Low resolution A/D converter 310 n converts analog input 309 n to digital output 311 n , and provides digital output 311 n to digital beamforming block 312 for digital beamforming. As shown in FIG. 3 , antenna 302 n also receives signal S 2 from wireless transmitter 398 b where signal S 2 is accompanied by noise Nn. Antenna 302 n further receives signal S 3 from wireless transmitter 398 c where signal S 3 is accompanied by noise Nn, and provides them to digital beamforming block 312 through path n for digital beamforming.

It should be noted that, although FIG. 3 shows antennas 302 a through 302 n as single, feed antennas, in another implementation, antennas 302 a through 302 n may be dual feed antennas with dual polarization feeds for a horizontally-polarized (H) signal and a vertically-polarized (V) signal. In that case, a signal accompanied by a noise received at each antenna and provided at each polarization feed passes through a separate LNA, mixer and A/D converter for each polarization.

As shown in FIG. 3 , wireless receiver 300 includes multiple antennas 302 a through 302 n each receiving signals S 1 , S 2 and S 3 from multiple wireless transmitters 398 a , 398 b and 398 c , where signals S 1 , S 2 and S 3 generally have an SNR greater than one. Wireless transmitters 398 a , 398 b and 398 c may send respective signals S 1 , S 2 and S 3 to each of antennas 302 a through 302 n , for example, using different channels within a frequency band. In the present implementation, since signals S 1 , S 2 and S 3 each have an SNR that is greater than one, the noise accompanying each signal is not dominant and can be substantially lower than the signal in the analog input provided to the corresponding A/D converter. Thus, assuming that signal S 1 is a desired signal over signals S 2 and S 3 , low resolution A/D converters 310 a through 310 n and digital beamforming block 312 of wireless receiver 300 may treat signals S 2 and S 3 as uncorrelated noises, so that signals S 2 and S 3 may have substantially the same effect as the uncorrelated dominant noises accompanying the signals transmitted from the single wireless transmitter in the implementation described with reference to FIGS. 2A through 2D , where the SNR was less than one.

In addition, as signals S 1 , S 2 and S 3 are provided to digital beamforming block 312 through paths 1 through n, digital beamforming block 312 has parallel paths to process the digital outputs from low resolution A/D converters 310 a through 310 n for each of the converted digital signals S 1 , S 2 and S 3 . Since signals S 1 , S 2 and S 3 arrive at antennas 302 a through 302 n from respective wireless transmitters 398 a , 398 b and 398 c from different directions (i.e. different incident angles), the different directions result in different path delays at antennas 302 a through 302 n . Based on these different path delays, digital beamforming block 312 may determine the direction at which each of signals S 1 , S 2 and S 3 arrives. Digital beamforming block 312 may function as a spatial filter to isolate the digital outputs of the desired signal (e.g., signal S 1 ) from the digital outputs of the other signals (e.g., signals S 2 and S 3 ). For example, digital beamforming block 312 may coherently add the digital outputs coining from a particular direction (for example, signal S 1 from wireless transmitter 398 a ), while incoherently adding digital outputs coming from other directions (for example, signal S 2 from wireless transmitter 398 b and signal S 3 from wireless transmitter 398 c ). Although only three wireless transmitters 398 a , 398 b , and 398 c are shown in FIG. 3 , in another implementation, wireless receiver 300 may receive signals from more than three wireless transmitters.

In one implementation, low resolution A/D converters 310 a through 310 n may be one-bit A/D converters. In another implementation, low resolution A/D converters 310 a through 310 n may be two-bit or three-bit A/D converters. Low resolution A/D converters 310 a through 310 n do not require programmable gain amplifiers or feedback loops, thus substantially reducing power consumption and increasing conversion speed, while reducing the required semiconductor area.

From the above description it is manifest that various techniques can be used for implementing the concepts described in the present application without departing from the scope of those concepts. Moreover, while the concepts have been described with specific reference to certain implementations, a person of ordinary skill in the art would recognize that changes can be made in form and detail without departing from the scope of those concepts. As such, the described implementations are to be considered in all respects as illustrative and not restrictive. It should also be understood that the present application is not limited to the particular implementations described above, but many rearrangements, modifications, and substitutions are possible without departing from the scope of the present disclosure.