Wireless device operable to detect a nearby object
A wireless device operable to detect a nearby object is disclosed. Herein, an object is considered a nearby object when a roundtrip propagation duration of a pulse(s) between an antenna and the object is less than two nanoseconds (2 ns). Given the close proximity of the object, an echo of the emitted pulse(s) may be reflected instantaneously toward the antenna to potentially overlap with the emitted pulse(s), thus causing difficulty in detecting the reflected pulse(s). In this regard, in embodiments disclosed herein, an acoustic delay circuit is provided in the wireless device to add a temporal delay in the emitted pulse(s) and the reflected pulse(s) to prevent the reflected pulse(s) from overlapping with the emitted pulse(s). As a result, the wireless device can accurately receive the reflected pulse(s) to thereby detect the nearby object.
1 . A wireless device comprising:
a transmitter circuit configured to generate an impulse waveform;
an antenna port coupled to an antenna configured to emit the impulse waveform toward a nearby object and absorb an echo of the emitted impulse waveform reflected by the nearby object;
a receiver circuit configured to receive the echo of the emitted impulse waveform; and
an acoustic delay circuit configured to:
receive the impulse waveform from the transmitter circuit;
delay the impulse waveform by a temporal delay;
provide the delayed impulse waveform to the antenna port;
receive the echo of the emitted impulse waveform from the antenna port;
delay the echo of the emitted impulse waveform by the temporal delay such that the echo of the emitted impulse waveform is delayed from the impulse waveform by twice the temporal delay; and
provide the delayed echo of the emitted impulse waveform to the receiver circuit.
2 . The wireless device of claim 1 , wherein the impulse waveform is an ultra-wideband (UWB) waveform.
3 . The wireless device of claim 1 , further comprising a transceiver circuit configured to:
generate the impulse waveform comprising a plurality of pulses; and
receive the echo of the emitted impulse waveform comprising a plurality of echoed pulses each corresponding to a respective one of the plurality of pulses in the impulse waveform reflected by the nearby object;
wherein the acoustic delay circuit is further configured to delay each of the impulse waveform and the echo of the emitted impulse waveform by the temporal delay to thereby prevent each of the plurality of echoed pulses from overlapping with the respective one of the plurality of pulses at the receiver circuit.
4 . The wireless device of claim 1 , further comprising:
a transmit switch provided between the transmitter circuit and the acoustic delay circuit;
a receive switch provided between the acoustic delay circuit and the receiver circuit; and
a control circuit configured to:
close the transmit switch and open the receive switch to thereby provide the impulse waveform from the transmitter circuit to the acoustic delay circuit; and
close the receive switch and open the transmit switch to thereby provide the delayed echo of the emitted impulse waveform from the acoustic delay circuit to the receiver circuit.
5 . The wireless device of claim 4 , further comprising an echo cancellation circuit configured to cancel an undesired echo caused by a coupling between the transmit switch and the receive switch in the echo of the emitted impulse waveform.
6 . The wireless device of claim 5 , wherein the acoustic delay circuit comprises a shunt circuit configured to assist in pre-calibration of the echo cancellation circuit.
7 . The wireless device of claim 1 , wherein the acoustic delay circuit comprises:
an acoustic device configured to delay each of the impulse waveform and the echo of the emitted impulse waveform by the temporal delay; and
a bypass switch configured to bypass the acoustic device.
8 . The wireless device of claim 7 , wherein the acoustic device comprises a substrate having a first surface and a second surface and corresponds to a thickness that causes the temporal delay in the impulse waveform and the echo of the emitted impulse waveform when the impulse waveform and the echo of the emitted impulse waveform propagate through the substrate.
9 . The wireless device of claim 8 , wherein the acoustic device further comprises:
a first anti-reflection layer provided on the first surface;
a first piezo layer provided on the first anti-reflection layer;
a second anti-reflection layer provided on the second surface; and
a second piezo layer provided on the first anti-reflection layer.
10 . The wireless device of claim 9 , wherein the acoustic device further comprises:
a third anti-reflection layer provided on the second piezo layer; and
an absorber layer provided on the third anti-reflection layer.
11 . A method for detecting a nearby object comprising:
generating an impulse waveform and delaying the impulse waveform by a temporal delay;
emitting the impulse waveform toward the nearby object and absorbing an echo of the emitted impulse waveform reflected by the nearby object;
delaying the echo of the emitted impulse waveform by the temporal delay such that the echo of the emitted impulse waveform is delayed from the impulse waveform by twice the temporal delay; and
receiving the delayed echo of the emitted impulse waveform.
12 . The method of claim 11 , further comprising:
generating the impulse waveform comprising a plurality of pulses;
emitting the impulse waveform toward the nearby object;
receiving an echo of the emitted impulse waveform comprising a plurality of echoed pulses each corresponding to a respective one of the plurality of pulses in the impulse waveform reflected by the nearby object; and
delaying each of the impulse waveform and the echo of the emitted impulse waveform by the temporal delay to thereby prevent each of the plurality of echoed pulses from overlapping with the respective one of the plurality of pulses.
13 . The method of claim 11 , further comprising alternating between generating the impulse waveform and receiving the delayed echo of the emitted impulse waveform based on a time-division scheme.
14 . The method of claim 13 , further comprising cancelling an undesired echo in the delayed echo of the emitted impulse waveform.
15 . The method of claim 11 , wherein generating the impulse waveform comprises generating an ultra-wideband (UWB) waveform.
16 . The method of claim 11 , wherein delaying the echo of the emitted impulse waveform by the temporal delay comprises delaying the echo of the emitted impulse waveform using an acoustic delay circuit.
17 . The method of claim 16 , further comprising:
delaying, using an acoustic device, each of the impulse waveform and the echo of the emitted impulse waveform by the temporal delay; and
bypassing the acoustic device using a bypass switch.
18 . The method of claim 17 , further comprising assembling the acoustic device to include a substrate corresponding to a thickness that causes the temporal delay in the impulse waveform and the echo of the emitted impulse waveform when the impulse waveform and the echo of the emitted impulse waveform propagate through the substrate.
19 . The method of claim 18 , further comprising:
providing a first anti-reflection layer on a first surface of the substrate;
providing a first piezo layer on the first anti-reflection layer;
providing a second anti-reflection layer on a second surface of the substrate; and
providing a second piezo layer on the first anti-reflection layer.
20 . The method of claim 19 , further comprising:
providing a third anti-reflection layer on the second piezo layer; and
providing an absorber layer on the third anti-reflection layer.