Helpfullness
12-1 1. What is the main purpose of an instrumentation amplifier and what are three of its key characteristics?
The main purpose of an instrumentation amplifier is to amplify small signals that occur on large common-mode voltages. The key characteristics are high input impedance, high CMRR, low output impedance, and low output offset. 2. What components do you need to construct a basic instrumentation amplifier?
Three op-amps and seven resistors are required to construct a basic instrumentation amplifier. 3. How is the gain determined in a basic instrumentation amplifier?
The gain is set by the external resistor Rg. 4. In a certain AD622 configuration, Rg = 10 k ohm. What is the voltage gain?
Av -= 6
12-2
1. In what types of applications are isolation amplifiers used?
Isolation amplifiers are used in medical equipment, power plant instrumentation, industrial processing, and automated testing. 2. What are the two stages in a typical isolation amplifier?
The two stages of an isolation amplifier are input and output. 3. How are the stages in an isolation amplifier connected?
The stages are connected by transformer coupling. 4. What is the purpose of the oscillator in an isolation amplifier?
The oscillator acts as a dc to ac converter so that the dc power can be ac coupled to the input and output stages.
12-3
1. What does OTA stand for?
OTA stands for Operational Trans conductance Amplifier. 2. If the bias current in an OTA is increased, does the Trans conductance increase or decrease?
Tran’s conductance increases with bias current. 3. What happens to the voltage gain if the OTA is connected as a fixed-voltage amplifier and the supply voltages are increased?
Assuming that the bias input is connected to the supply voltage, the voltage gain increases when the supply voltage is increased because this increases the bias current. 4. What happens to the voltage gain if the OTA is connected as a variable-gain
The main purpose of an instrumentation amplifier is to amplify small signals that occur on large common-mode voltages. The key characteristics are high input impedance, high CMRR, low output impedance, and low output offset. 2. What components do you need to construct a basic instrumentation amplifier?
Three op-amps and seven resistors are required to construct a basic instrumentation amplifier. 3. How is the gain determined in a basic instrumentation amplifier?
The gain is set by the external resistor Rg. 4. In a certain AD622 configuration, Rg = 10 k ohm. What is the voltage gain?
Av -= 6
12-2
1. In what types of applications are isolation amplifiers used?
Isolation amplifiers are used in medical equipment, power plant instrumentation, industrial processing, and automated testing. 2. What are the two stages in a typical isolation amplifier?
The two stages of an isolation amplifier are input and output. 3. How are the stages in an isolation amplifier connected?
The stages are connected by transformer coupling. 4. What is the purpose of the oscillator in an isolation amplifier?
The oscillator acts as a dc to ac converter so that the dc power can be ac coupled to the input and output stages.
12-3
1. What does OTA stand for?
OTA stands for Operational Trans conductance Amplifier. 2. If the bias current in an OTA is increased, does the Trans conductance increase or decrease?
Tran’s conductance increases with bias current. 3. What happens to the voltage gain if the OTA is connected as a fixed-voltage amplifier and the supply voltages are increased?
Assuming that the bias input is connected to the supply voltage, the voltage gain increases when the supply voltage is increased because this increases the bias current. 4. What happens to the voltage gain if the OTA is connected as a variable-gain