Multi-level pulser and related apparatus and methods
Inventors
Chen, Kailiang • Ralston, Tyler S.
Assignees
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Publication Number
US-9933516-B2
Publication Date
2018-04-03
Expiration Date
Abstract
Apparatus and methods are provided directed to a device, including at least one ultrasonic transducer, a multi-level pulser coupled to the at least one ultrasonic transducer; the multi-level pulser including a plurality of input terminals configured to receive respective input voltages, an output terminal configured to provide an output voltage, and a signal path between a first input terminal and the output terminal including a first transistor having a first conductivity type coupled to a first diode and, in parallel, a second transistor having a second conductivity type coupled to a second diode.
Core Innovation
The invention relates to an apparatus for generating an ultrasound pulse that uses a level shifter and a pulser to generate plurality of multi-level pulses. The level shifter has an input terminal configured to receive an input signal having two or more states and outputs one or more control signals at an output terminal. The pulser receives the one or more control signals and provides a plurality of multi-level pulses corresponding to the received control pulses.
The apparatus includes a capacitive micromachined ultrasonic transducer (CMUT) configured to receive the plurality of multi-level pulses from the pulser and convert each multi-level pulse to an acoustic ultrasound signal. Each acoustic ultrasound signal corresponds to one of the plurality of multi-level pulses. In this architecture, the CMUT is an ultrasound transducer driven by multi-level electrical pulses produced from control signals generated through the level shifter and pulser.
Heat management is incorporated into the architecture by configuring the level shifter and the pulser to dissipate heat when an ultrasound signal level is changed corresponding to the plurality of multi-level pulses. The disclosure also describes a multi-level pulser architecture with parallel transistor-diode branches of opposite conductivity types, and operation that corresponds to N-level pulses. Integration options are described in which components such as the CMUT can be integrated monolithically on a shared semiconductor substrate/die.
Claims Coverage
Independent claim coverage includes three main inventive components: a level shifter producing control signals from a multi-state input, a pulser that converts those control signals into plurality of multi-level pulses, and a CMUT that converts each multi-level pulse into corresponding acoustic ultrasound signals, with heat dissipation configured during ultrasound signal level changes. Dependent claims add architectural refinements such as solid-state chip integration, specific level-shifter subcomponents, specific pulser signal-path transistor/diode arrangements, charge recycling control, and additional electrical relationships between input and output voltages.
Multi-state level shifting with control signals
A level shifter having an input terminal configured to receive an input signal having two or more states and configured to output one or more control signals at the output terminal.
Pulser generating plurality of multi-level pulses
A pulser to communicate with the level shifter, the pulser configured to receive the one or more control signals from the level shifter and to provide a plurality of multi-level pulses corresponding to the one or more control pulses received from the level shifter.
CMUT converting each multi-level pulse to corresponding acoustic ultrasound signals
A capacitive micromachined ultrasonic transducer (CMUT) configured to receive the plurality of multi-level pulses from the pulser and convert each of the plurality of multi-level pulses to an acoustic ultrasound signal, each acoustic ultrasound signal corresponding to one of the plurality of multilevel pulses.
Heat dissipation upon ultrasound signal level change
The level shifter and the pulser are configured to dissipate heat when an ultrasound signal level is changed corresponding to the plurality of multi-level pulses.
Monolithic integration on solid-state chip
The level shifter and the pulser are integrated into a solid-state chip and the CMUT is configured to receive the plurality of multi-level pulses from the pulser on the solid-state chip.
Level shifter with capacitors and reverse-biased diodes
The level shifter includes one or more capacitors between the voltage input terminal and the output voltage terminal and one or more reverse-biased diodes between an input to an active high voltage element and a first voltage of a high voltage power supply.
Parallel transistor-diode signal paths of opposite conductivity types
A signal path of the pulser includes a first transistor of a first conductivity type coupled to a first diode in parallel with a second transistor of a second conductivity type coupled to a second diode, and the pulser includes multiple input terminals and an output terminal.
Charge recycling control for output capacitance
The pulser includes a controller configured to control a charge and discharge of an output capacitance to provide charge recycling.
Output voltage equals predetermined input voltage
The apparatus is configured so that its output voltage equals a predetermined input voltage.
The core claim coverage is the combination of a level shifter producing control signals from a multi-state input, a pulser producing plurality of multi-level pulses, and a CMUT converting each multi-level pulse into a corresponding acoustic ultrasound signal, together with configured heat dissipation during ultrasound signal level changes. Dependent features further narrow the architecture to specific solid-state integration, specific level-shifter components using capacitors and reverse-biased diodes, specific pulser signal paths using parallel transistor/diode branches of opposite conductivity types, optional charge recycling control, and an explicit output voltage equality relationship.
Stated Advantages
Multi-level pulses reduce power consumption versus 2-level pulses.
Static power consumption is negligible because heat in the described level shifter is dissipated mainly during switching when the ultrasound signal level is changed.
Documented Applications
Generating ultrasound pulses using a capacitive micromachined ultrasonic transducer (CMUT), including operation consistent with high-intensity focused ultrasound (HIFU).
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