What is a Source Measurement Unit (SMU)? What is the difference from a multimeter?
A Source Measurement Unit (SMU) is an instrument that combines a signal source function and a measurement function on the same pin or connector. It can supply voltage or current and measure voltage and/or current simultaneously. It integrates the functions of a power supply or function generator, a digital multimeter (DMM) or oscilloscope, a current source, and an electronic load into a single, tightly synchronised instrument.
The difference between an SMU and a multimeter is that an SMU can not only measure a wide range of electrical parameters, but also output voltages and currents, thus enabling a source-measure cycle for the object under test. A multimeter can only measure parameters such as voltage, current, and resistance, and cannot be used as a power source or load.SMUs also have higher functionality and accuracy, but are relatively more expensive.
The measurement range of an SMU is the maximum and minimum values of voltage or current that the SMU can measure. Different SMU models have different measurement ranges. Generally speaking, the larger the measurement range, the lower the resolution, and vice versa. For example, a certain SMU model has a voltage measurement range of 200V with a resolution of 100μV and a current measurement range of 1A with a resolution of 10nA.
When using the SMU for low current measurement, the following points need to be noted:
- Select the appropriate current measurement range and resolution to avoid overload or underload conditions.
- Use the four-wire remote sensing method to eliminate the influence of wire resistance and ensure the accuracy of the measurement results.
- Use shielded cables and grounding measures to reduce interference from external noise.
- Use the offset compensation function to eliminate zero drift and reference error in the measurement circuit.
SMU power supply refers to the output function of SMU, which can be used as a programmable voltage source or current source to provide precise voltage or current to the measured object. SMU power supply has the feature of four-quadrant output, i.e., it can output positive and negative voltages and currents, or absorb positive and negative voltages and currents, to achieve excitation and loading of the measured object.
Which is more common, SMU or multimeter? It depends on your application scenarios and needs. Generally speaking, a multimeter is a more common electronic test instrument because it can measure a wide range of electrical parameters and is relatively inexpensive. A multimeter is suitable for some simple circuit testing and troubleshooting, such as measuring the voltage of a battery, the resistance of a resistor, the capacitance of a capacitor, etc. An SMU is a more advanced electronic test instrument because it can not only measure voltages and currents, but also output voltages and currents, thus realising source-measurement loops of the object to be tested.SMUs are suitable for some complex electronic test applications, such as characterising the electrical properties of various electrical properties of materials and devices, such as diodes, solar cells, transistors, sensors, etc. SMUs are relatively more expensive, but they also have higher functionality and accuracy. According to some articles I searched on the web https://www.bilibili.com/read/cv19588211/, the market share of SMU is relatively low, but its market growth rate is relatively high because of its technological innovations and expanding application areas. Therefore, there is no absolute answer as to how common SMUs and multimeters are, but rather it is a matter of choosing the right instrument for your specific needs and budget.
The four-quadrant output of SMU means that SMU can work in four quadrants, i.e., it can output positive and negative voltages and positive and negative currents, and it can also absorb positive and negative voltages and positive and negative currents. As shown in the figure below, in the first and third quadrants, the SMU outputs power as a power source, i.e., it provides power to the object under test; in the second and fourth quadrants, the SMU absorbs power as a load, i.e., it consumes power from the object under test. This four-quadrant output allows the SMU to achieve excitation and loading of the object under test, as well as a complete characterisation of its electrical properties.
The pros and cons of SMUs are a subjective matter and different people may have different opinions. Based on some articles I have searched from the internet, I have tried to summarise the following points:
Pros:
- The SMU is an all-in-one electronic test instrument that provides accurate voltage source, current source, voltmeter, ammeter, and resistance meter capabilities, saving test time and cost.
- Featuring a four-quadrant output, the SMU enables the excitation and loading of the object under test, as well as the complete characterisation of its electrical properties, making it suitable for a wide range of complex electronic test applications.
- With high accuracy and resolution, the SMUs can measure extremely low voltages and currents, as well as very high resistances and capacitances, meeting high-end test requirements.
- The SMUs offer additional flexibility and convenience with a variety of measurement modes and functions, such as constant voltage mode, constant current mode, sweep mode, offset compensation function, and remote sense function.
- With good programmability and compatibility, SMUs can be controlled and data processed through a variety of interfaces and software, supporting a wide range of test standards and protocols.
Disadvantages:
- SMUs are relatively expensive and may not be the most economical choice for some low-end or simple test applications.
- The operation and use of SMUs is relatively complex and requires certain professional knowledge and skills, which may not be the most convenient choice for some beginners or non-professionals.
- The output power of SMU is relatively low, which may not be the most suitable choice for some test applications requiring high current or high voltage.
A Source Measurement Unit (SMU) is an instrument that combines a signal source function and a measurement function on the same pin or connector. It can supply voltage or current and measure voltage and/or current simultaneously. It integrates the functions of a power supply or function generator, a digital multimeter (DMM) or oscilloscope, a current source, and an electronic load into a single, tightly synchronised instrument.
The difference between an SMU and a multimeter is that an SMU can not only measure a wide range of electrical parameters, but also output voltages and currents, thus enabling a source-measure cycle for the object under test. A multimeter can only measure parameters such as voltage, current, and resistance, and cannot be used as a power source or load.SMUs also have higher functionality and accuracy, but are relatively more expensive.
The measurement range of an SMU is the maximum and minimum values of voltage or current that the SMU can measure. Different SMU models have different measurement ranges. Generally speaking, the larger the measurement range, the lower the resolution, and vice versa. For example, a certain SMU model has a voltage measurement range of 200V with a resolution of 100μV and a current measurement range of 1A with a resolution of 10nA.
When using the SMU for low current measurement, the following points need to be noted:
- Select the appropriate current measurement range and resolution to avoid overload or underload conditions.
- Use the four-wire remote sensing method to eliminate the influence of wire resistance and ensure the accuracy of the measurement results.
- Use shielded cables and grounding measures to reduce interference from external noise.
- Use the offset compensation function to eliminate zero drift and reference error in the measurement circuit.
SMU power supply refers to the output function of SMU, which can be used as a programmable voltage source or current source to provide precise voltage or current to the measured object. SMU power supply has the feature of four-quadrant output, i.e., it can output positive and negative voltages and currents, or absorb positive and negative voltages and currents, to achieve excitation and loading of the measured object.
Which is more common, SMU or multimeter? It depends on your application scenarios and needs. Generally speaking, a multimeter is a more common electronic test instrument because it can measure a wide range of electrical parameters and is relatively inexpensive. A multimeter is suitable for some simple circuit testing and troubleshooting, such as measuring the voltage of a battery, the resistance of a resistor, the capacitance of a capacitor, etc. An SMU is a more advanced electronic test instrument because it can not only measure voltages and currents, but also output voltages and currents, thus realising source-measurement loops of the object to be tested.SMUs are suitable for some complex electronic test applications, such as characterising the electrical properties of various electrical properties of materials and devices, such as diodes, solar cells, transistors, sensors, etc. SMUs are relatively more expensive, but they also have higher functionality and accuracy. According to some articles I searched on the web https://www.bilibili.com/read/cv19588211/, the market share of SMU is relatively low, but its market growth rate is relatively high because of its technological innovations and expanding application areas. Therefore, there is no absolute answer as to how common SMUs and multimeters are, but rather it is a matter of choosing the right instrument for your specific needs and budget.
The four-quadrant output of SMU means that SMU can work in four quadrants, i.e., it can output positive and negative voltages and positive and negative currents, and it can also absorb positive and negative voltages and positive and negative currents. As shown in the figure below, in the first and third quadrants, the SMU outputs power as a power source, i.e., it provides power to the object under test; in the second and fourth quadrants, the SMU absorbs power as a load, i.e., it consumes power from the object under test. This four-quadrant output allows the SMU to achieve excitation and loading of the object under test, as well as a complete characterisation of its electrical properties.
The pros and cons of SMUs are a subjective matter and different people may have different opinions. Based on some articles I have searched from the internet, I have tried to summarise the following points:
Pros:
- The SMU is an all-in-one electronic test instrument that provides accurate voltage source, current source, voltmeter, ammeter, and resistance meter capabilities, saving test time and cost.
- Featuring a four-quadrant output, the SMU enables the excitation and loading of the object under test, as well as the complete characterisation of its electrical properties, making it suitable for a wide range of complex electronic test applications.
- With high accuracy and resolution, the SMUs can measure extremely low voltages and currents, as well as very high resistances and capacitances, meeting high-end test requirements.
- The SMUs offer additional flexibility and convenience with a variety of measurement modes and functions, such as constant voltage mode, constant current mode, sweep mode, offset compensation function, and remote sense function.
- With good programmability and compatibility, SMUs can be controlled and data processed through a variety of interfaces and software, supporting a wide range of test standards and protocols.
Disadvantages:
- SMUs are relatively expensive and may not be the most economical choice for some low-end or simple test applications.
- The operation and use of SMUs is relatively complex and requires certain professional knowledge and skills, which may not be the most convenient choice for some beginners or non-professionals.
- The output power of SMU is relatively low, which may not be the most suitable choice for some test applications requiring high current or high voltage.