What are the types of voltage references?

Types of voltage references is 

• Shunt voltage reference
• Series voltage reference
• Bandgap voltage reference

Shunt voltage reference

Basically shunt voltage references are two-terminal types designed to operate in parallel with their load over a specific current range. When not in use, the shunt removes enough current to achieve the correct output voltage while reducing the reference voltage drop. Under load, however, it will automatically decrease the sink current to maintain a constant throughput.

And as a result, the shunt voltage reference will effectively regulate the output voltage by changing its sink current to accommodate load fluctuations. In practice, this approach is functionally equivalent to the one used in Zener diodes. Shunt voltage references in a small and simple PCB footprint demonstrate very good stability and accuracy over a wide range of variable current and load conditions.

Moreover, as a negative voltage reference, a shunt voltage reference is easy to construct and can be used with very high and low supply voltages.

Series voltage reference

Essentially series voltage references consist of three or more terminals and require a constant source current over a wide voltage range. And an important advantage is that they draw load and current from the input supply when the load is required. Due to this mechanism, this type is suitable for use in circuits where the load current or power supply voltage varies dramatically over time. Moreover, the absence of a resistor between the power supply and the reference makes the latter especially useful for circuits with large loads. The absence of an external resistor in a three-terminal series voltage reference simplifies (and compacts) its overall design, as well as reducing power consumption.

Bandgap voltage reference

Basically a temperature-independent bandgap voltage reference circuit. And these types of component voltage references are becoming increasingly common in integrated circuits. It is used to produce a stable (constant) voltage regardless of power supply fluctuations, device circuit loading, or most importantly operating temperature. Bandgap voltage reference circuits effectively erase the restrictions of negative temperature dependence of other voltage reference types. This is achieved using a positive temperature-dependent ratio-to-temperature (PTAT) circuit. This enables much more stable and reliable performance than most Zener and other commonly used negative temperature-dependent voltage reference diodes. Precision voltage reference circuits currently make widespread use of bandgap variation. They are used in a variety of precision voltage reference ICs where temperature stability and low noise performance are critical factors.