Apparatus and method for transmit/receive switching

An apparatus comprising:

• a transmitter coupled to an ultrasonic transducer at a first node, the transmitter being configured to generate a first signal during a transmit period;
• a transmit/receive switch having an input coupled to the first node, wherein the transmit/receive switch further comprises:
• one or more field effect transistors (FETs) coupled between the first node and a second node, wherein the one or more FETs are configured to be turned on during a receive period to couple the first node and the second node such that a second signal is passed from the first node to the second node during the receive period, and to be turned off during the transmit period to substantially block the first signal from the second node;
• and
• a clamp circuit coupled to the second node, wherein the clamp circuit is configured to protect the second node from excess voltages;
• a receiver having an input coupled to the second node to receive a second signal during the receive period, wherein the second signal is intended to comprise echoes of the first signal;
• and
• a low voltage to high voltage (LV to HV) level translator configured to generate a MOSFET control signal for switching on or off the one or more MOSFETs at least partly in response to a transmit/receive control signal,
• wherein the LV to HV level translator comprises:
• a first high voltage single gate transistor including a source coupled to a first voltage source, a drain coupled to a first translator node, and a gate coupled to a second translator node;
• a second high voltage single gate transistor including a source coupled to the first voltage source, a drain coupled to the second translator node, and a gate coupled to the first translator node;
• a first dual gate transistor including a drain coupled to the first translator node, a source coupled to a second voltage source, and a gate coupled to receive the transmit/receive control signal;
• and
• a second dual gate transistor including a drain coupled to the second translator node, a source coupled to the second voltage source, and a gate coupled to receive a signal inverted from the transmit/receive control signal.

An apparatus comprising:

• a transmitter coupled to an ultrasonic transducer at a first node, the transmitter being configured to generate a first signal during a transmit period;
• a transmit/receive switch having an input coupled to the first node, wherein the transmit/receive switch further comprises:
• one or more field effect transistors (FETs) coupled between the first node and a second node, wherein the one or more FETs are configured to be turned on during a receive period to couple the first node and the second node such that a second signal is passed from the first node to the second node during the receive period, and to be turned off during the transmit period to substantially block the first signal from the second node;
• and
• a clamp circuit coupled to the second node, wherein the clamp circuit is configured to protect the second node from excess voltages;
• a receiver having an input coupled to the second node to receive a second signal during the receive period, wherein the second signal is intended to comprise echoes of the first signal;
• a low voltage to high voltage (LV to HV) level translator configured to generate a MOSFET control signal for switching on or off the one or more MOSFETs at least partly in response to a transmit/receive control signal;
• a high voltage to low voltage (HV to LV) level translator configured to generate a first clamp control signal for controlling the switching of the clamp circuit at least partly in response to the MOSFET control signal;
• and
• a clamp control latch configured to generate a second clamp control signal at least partly in response to the first clamp control signal, wherein the second clamp control signal is configured to switch on or off the clamp circuit.

A method of operating an electronic device, the method comprising:

• generating, by a transmitter, an ultrasound signal during a transmit period;
• receiving, by a receiver, an echo signal during a receive period;
• and
• electrically blocking the receiver from the transmitter during the transmit period, by turning off one or more metal-oxide-semiconductor field effect transistors (MOSFETs) coupled between an input node and an output node, the input node being electrically coupled to the transmitter, the output node being electrically coupled to the receiver;
• passing the echo signal to the receiver during the receive period by turning on the one or more MOSFETs,
• wherein electrically blocking the receiver comprises coupling the output node to ground during the transmit period.