ClaudioKlein
Newbie level 3
I’m a Brazilian researcher designing an ultrasound range finder for Biomedical Department. This is a picture from Orcad project schematic: http://vesatur.sites.uol.com.br/temp/schematic.jpg
I placed an AC generator (Vin) to simulate the ultrasound reflected wave with 1mV amplitude and 700kHz.
This is the simulation: http://vesatur.sites.uol.com.br/temp/simulation.jpg
Gain = 41dB.
I’m designing an ultrasound receiver with AD600 (Analog Devices) to amplify the reflected wave with a preamp supplied by an OPA350. I’m really confused with all those AD600 ground connections and I’m aware if I make a mistake it will produce a lot of noise and it will interfere in my measures. The AD600 IC provides separated ground references for input (A1LO/A2LO) and output (A1CM/A2CM). Datasheet warns: “It is important that A1LO and A2LO be connected directly to the input ground. Significant impedance in these connections reduces the gain accuracy. A1CM and A2CM should be connected to the load ground.”
I’m using the same single transducer element for transmission and reception then transducer has to be connected with transmitter and receiver circuits. In my schematic, I labeled ground plane with number 1. These are my ground considerations:
• Label 1 - I attached all transmitter components and DC regulators connected to VPOS (pin 13) and VNEG (pin 12) in AD600 to ground plane.
• Label 2 - I presumed that I should connect the input grounds (A1LO – pin 3 /A2LO – pin 6) and gate input (GAT1 – pin 4/ GAT2 – pin 5). At the same reference, I connected the voltage limiter made by 1n4937 diodes and the preamp ground connection.
• Label 3 - I connected the output ground pins (A1CM – pin 15 / A2CM – pin 10) with the load resistor as an output ground reference.
Where should I connect the transducer? There are 2 options: the ground plane with the transmitter components or with the AD600 input ground reference.
Should I isolate AD600 ground reference from next stage (buffer + peak detector)? Is it safe connecting peak detector and AD ground output to ground plane?
I’m so sorry for my poor English.
Thanks in advance,
Claudio Klein
I placed an AC generator (Vin) to simulate the ultrasound reflected wave with 1mV amplitude and 700kHz.
This is the simulation: http://vesatur.sites.uol.com.br/temp/simulation.jpg
Gain = 41dB.
I’m designing an ultrasound receiver with AD600 (Analog Devices) to amplify the reflected wave with a preamp supplied by an OPA350. I’m really confused with all those AD600 ground connections and I’m aware if I make a mistake it will produce a lot of noise and it will interfere in my measures. The AD600 IC provides separated ground references for input (A1LO/A2LO) and output (A1CM/A2CM). Datasheet warns: “It is important that A1LO and A2LO be connected directly to the input ground. Significant impedance in these connections reduces the gain accuracy. A1CM and A2CM should be connected to the load ground.”
I’m using the same single transducer element for transmission and reception then transducer has to be connected with transmitter and receiver circuits. In my schematic, I labeled ground plane with number 1. These are my ground considerations:
• Label 1 - I attached all transmitter components and DC regulators connected to VPOS (pin 13) and VNEG (pin 12) in AD600 to ground plane.
• Label 2 - I presumed that I should connect the input grounds (A1LO – pin 3 /A2LO – pin 6) and gate input (GAT1 – pin 4/ GAT2 – pin 5). At the same reference, I connected the voltage limiter made by 1n4937 diodes and the preamp ground connection.
• Label 3 - I connected the output ground pins (A1CM – pin 15 / A2CM – pin 10) with the load resistor as an output ground reference.
Where should I connect the transducer? There are 2 options: the ground plane with the transmitter components or with the AD600 input ground reference.
Should I isolate AD600 ground reference from next stage (buffer + peak detector)? Is it safe connecting peak detector and AD ground output to ground plane?
I’m so sorry for my poor English.
Thanks in advance,
Claudio Klein