Reference Pin on Differential Amplifier

In summary, the conversation discusses using a differential amplifier to separate the digital and analog ground portions of a circuit. The speaker is unsure about the datasheet of the available amplifiers and asks for clarification on the reference pin. It is clarified that the output of the amplifier will be referenced to whichever ground is connected to the reference pin. The speaker plans to power the amplifier from a floating lab supply referenced to analog ground but wants the signal to go into an Arduino powered by a wall wart. It is suggested to connect the reference pin to the digital ground on the Arduino, which is the ground reference for the A-D converter. The speaker also mentions the importance of minimizing noise and DC offsets by connecting the reference terminal close to the Arduino ground pin.
  • #1
teroenza
195
5
I want to use a differential amplifier to separate the digital and analog ground portions of a circuit, but am not confident in my understanding of the datasheet of the amps I have on hand (amp03).

http://www.analog.com/media/en/technical-documentation/data-sheets/AMP03.pdf

I think that (looking at page 5), the output of the amp will be referenced to whichever ground I connect to the reference pin (pin #1). Does this make sense? For example, I plan to power the amp from a supply (floating lab supply) referenced to analog ground, but want it's signal to go into an Arduino (powered by a wall wart), so I would connect the reference pin to digital ground in that case.
 
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  • #2
teroenza said:
so I would connect the reference pin to digital ground in that case.
Yes, if the digital ground on the Arduino is the ground reference for the A-D converter.
 
  • #3
Thank you. Specifically for my circuit I would like:

signal in wrt analog ground --> [amp03] --> Arduino+A-D (ref. to Ardunio ground) --> [amp03] --> signal wrt analog ground
 
  • #4
Currents flowing in the ground conductors can be a problem. You can minimise noise and DC offsets by making sure that the reference terminal is attached as close as possible to the Arduino ground pin.
 

1. What is a reference pin on a differential amplifier?

A reference pin on a differential amplifier is a pin that is used to provide a stable and fixed voltage or current reference for the amplifier circuit. It is typically connected to a stable voltage source, such as a voltage reference chip or a precision resistor, and serves as a point of comparison for the differential input signals.

2. Why is a reference pin necessary for a differential amplifier?

A reference pin is necessary for a differential amplifier to ensure accurate and stable operation. Without a reference pin, the amplifier would be susceptible to fluctuations in the power supply or other external factors, which could result in inaccurate measurements or distorted output signals. The reference pin helps to stabilize the amplifier and provide a consistent point of comparison for the input signals.

3. How is a reference pin typically connected in a differential amplifier circuit?

The reference pin is typically connected to a stable voltage source, such as a voltage reference chip or a precision resistor, through a low-impedance connection. This helps to minimize any noise or interference from the power supply or other components in the circuit. Additionally, the reference pin is usually connected to the non-inverting input of the amplifier, which allows for a more precise comparison of the input signals.

4. Can a differential amplifier function without a reference pin?

Technically, a differential amplifier can function without a reference pin, but it may not provide accurate or stable output signals. The reference pin helps to improve the performance of the amplifier by providing a stable point of comparison for the input signals. Without a reference pin, the amplifier may be more susceptible to noise and external factors, which could result in distorted or inaccurate output.

5. Are there different types of reference pins used in differential amplifiers?

Yes, there are different types of reference pins that can be used in differential amplifiers depending on the specific application and circuit design. Some common types include voltage reference chips, precision resistors, and zener diodes. Each type has its own advantages and limitations, so the choice of reference pin will depend on the requirements of the circuit.

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