Symmetric receiver switch for bipolar pulser
Circuitry for ultrasound devices is described. A multilevel pulser is described, which can provide bipolar pulses of multiple levels. The multilevel pulser includes a pulsing circuit and pulser and feedback circuit. Symmetric switches are also described. The symmetric switches can be positioned as inputs to ultrasound receiving circuitry to block signals from the receiving circuitry.
1. A method of operating an ultrasound device, comprising:
providing a pulser signal to an ultrasonic transducer during a transmit mode of operation of the ultrasound device;
operating a symmetric switch having an input terminal coupled between the ultrasonic transducer and a receiving circuit in an open state during the transmit mode of operation;
operating the symmetric switch in a closed state during a receive mode of operation of the ultrasound device; and
converting, using a current-to-voltage converter of the receiving circuit, a current from the ultrasonic transducer to a voltage during the receive mode of operation, wherein:
the symmetric switch comprises a first transistor and a second transistor, the first transistor having a first gate, a first source, and a first drain, and the second transistor having a second gate, a second source, and a second drain, the first gate being connected to the second gate, and the first source being connected to the second source, and
wherein operating the symmetric switch in the open state during the transmit mode of operation of the ultrasound device comprises coupling the first gate and the second gate to a first terminal producing a first control signal and coupling the first source and the second source to a second terminal producing a second control signal, the first control signal and the second control signal having a first same electric potential at a first time and a second same electric potential at a second time.
2. The method of claim 1 , wherein the current-to-voltage converter comprises a trans-impedance amplifier (TIA), and converting the current from the ultrasonic transducer to the voltage during the receive mode of operation is performed using the TIA.
3. The method of claim 1 , further comprising operating a third transistor during the receive mode and the transmit mode.
4. The method of claim 3 , wherein the third transistor has a third gate, a third drain connected to the second drain, and a third source, and wherein operating the third transistor comprises:
during the receive mode, coupling the third gate to a third electric potential; and
during the transmit mode, coupling the third gate to a fourth electric potential that is greater than the third electric potential.
5. The method of claim 3 , wherein the third transistor has a third gate, a third drain connected to the second drain, and a third source, and wherein the method further comprises coupling the third source to a ground potential.
6. The method of claim 1 , wherein the first same electric potential is greater than the second same electric potential.
7. The method of claim 1 , wherein the first control signal and the second control signal have the first same electric potential at a third time.
8. The method of claim 4 , wherein coupling the third gate to the third electric potential and the fourth electric potential comprises coupling the third gate to a third terminal producing a third control signal.
9. The method of claim 8 , wherein the third control signal has the third electric potential at a fourth time and the fourth electric potential at the first time.