Transmit/receive system for imaging devices
A transmit/receive system for an imaging device includes a transmit circuit configured to generate and output test pulses to a transducer of a probe to cause the probe to propagate an ultrasonic wave through an object. A receive circuit is configured to receive, from the transducer, a composite signal that includes the test pulses output by the transmit circuit and a reflected signal corresponding to reflected waves sensed by the transducer in response to the ultrasonic wave propagated through the object and filter the test pulses from the composite signal and output the reflected signal in accordance with a predetermined minimum frequency of the reflected signal.
1. A transmit/receive system for an imaging device, the transmit/receive system comprising:
a transmit circuit configured to generate and output test pulses to a transducer of a probe to cause the probe to propagate an ultrasonic wave through an object; and
a receive circuit configured to
receive, from the transducer, a composite signal that includes (i) the test pulses output by the transmit circuit and (ii) a reflected signal, wherein the reflected signal corresponds to reflected waves sensed by the transducer in response to the ultrasonic wave propagated through the object, and
filter the test pulses from the composite signal and output the reflected signal in accordance with a predetermined minimum frequency of the reflected signal.
2. The transmit/receive system of claim 1 , wherein, to filter the test pulses, the receive circuit includes a filter circuit configured to filter the test pulses in accordance with a cutoff frequency that is less than the predetermined minimum frequency of the reflected signal.
3. The transmit/receive system of claim 2 , wherein the filter circuit includes a diode bridge.
4. The transmit/receive system of claim 3 , wherein the diode bridge includes diodes having forward transit times that are greater than a predetermined value, wherein the predetermined value is selected in accordance with the predetermined minimum frequency of the reflected signal.
5. The transmit/receive system of claim 4 , wherein the predetermined value corresponds to 1/(2*π*f), and wherein f is the predetermined minimum frequency of the reflected signal.
6. The transmit/receive system of claim 3 , wherein the diode bridge has an impedance of substantially zero at frequencies between the predetermined minimum frequency and a predetermined maximum frequency of the reflected signal.
7. The transmit/receive system of claim 2 , further comprising a clipper circuit configured to limit a magnitude of an output of the filter circuit.
8. The transmit/receive system of claim 7 , further comprising:
an amplifier that amplifies the output of the filter circuit and that outputs an amplified voltage; and
a processing module configured to generate a signal for displaying the image of the object based on the amplified voltage.
9. The transmit/receive system of claim 2 , wherein, to filter the test pulses, the filter circuit is configured to filter the test pulses based on (i) respective magnitudes of the test pulses and (ii) a bias voltage.
10. The transmit/receive system of claim 9 , wherein a magnitude of the bias voltage is less than the respective magnitudes of the test pulses.
11. The transmit/receive system of claim 9 , wherein a maximum value of the reflected signal is less than a magnitude of the bias voltage.
12. A method of operating an imaging device, the method comprising:
generating and outputting test pulses to a transducer of a probe to cause the probe to propagate an ultrasonic wave through an object;
receiving, from the transducer, a composite signal that includes (i) the test pulses and (ii) a reflected signal, wherein the reflected signal corresponds to reflected waves sensed by the transducer in response to the ultrasonic wave propagated through the object; and
filtering the test pulses from the composite signal and outputting the reflected signal in accordance with a predetermined minimum frequency of the reflected signal.
13. The method of claim 12 , wherein filtering the test pulses includes filtering the test pulses in accordance with a cutoff frequency that is less than the predetermined minimum frequency of the reflected signal.
14. The method of claim 13 , wherein filtering the test pulses includes filtering the test pulses using a diode bridge.
15. The method of claim 14 , wherein the diode bridge includes diodes having forward transit times that are greater than a predetermined value, the method further comprising selecting the predetermined value in accordance with the predetermined minimum frequency of the reflected signal.
16. The method of claim 15 , wherein the predetermined value corresponds to 1/(2*π*f), and wherein f is the predetermined minimum frequency of the reflected signal.
17. The method of claim 14 , wherein the diode bridge has an impedance of substantially zero at frequencies between the predetermined minimum frequency and a predetermined maximum frequency of the reflected signal.
18. The method of claim 13 , wherein filtering the test pulses includes filtering the test pulses based on (i) respective magnitudes of the test pulses and (ii) a bias voltage.
19. The method of claim 18 , wherein a magnitude of the bias voltage is less than the respective magnitudes of the test pulses.
20. The method of claim 18 , wherein a maximum value of the reflected signal is less than a magnitude of the bias voltage.