Voltage Reference IP Core

A voltage reference is an IP Core that is able to produce a “reference” voltage regardless of the changes produced in extraneous factors associated with the circuit or device. This means that irrespective of the variations that may be experienced in the time, power supply, loading, humidity, or temperature around the device, it will continue to produce a constant voltage that will act as the reference. The fixed output voltage is a direct current or DC.

The primary job of the voltage reference IP Core is to continuously provide a reference or fixed voltage which can be used by the other components in the circuit or system to measure and control their own factors. The other components of the system will compare their own input voltages against this reference voltage and make the necessary adjustments to maintain consistency and accuracy in the results. We are surrounded by analog signals and we need to find a way to bridge the gap between the analog world and digital technology. The voltage reference plays a critical role in making this translation a success as it gives the technology a standard to judge the incoming analog voltage signals and convert them into accurately quantified measurable quantities to simplify computation.

Voltage reference devices are also sometimes referred to as classes or categories of PMICs which are Power Management Integrated Circuits. In the modern day, they are used in a number of devices and electronic products, inducing analog to digital converters, digital to analog converters, as well as basic power supply systems.

Types of Voltage Reference IP Core

Voltage references IP Cores can be broadly categorized into three different types:

Charged Capacitor

The applications of Charged Capacitor voltage references is largely limited to safety applications and is not used widely because of its relative instability due to ionizing radiation. This means that different types of rays can easily discharge the capacitor when exposed to it, making it extremely unstable and of limited use.

Zener

Zeners, on the other hand, are used in many electronic devices. They are usually used in avalanche mode where the diode emits a stable voltage over a given range of current.

Bandgap

The most commonly found voltage reference in ICs is the bandgap type. The bandgap voltage reference uses two transistor junctions having varying current densities and temperature coefficients to make the temperature curve flat. The two bipolar junctions are then used to drive a voltage across the diode.

Choosing a Voltage Reference IP Core

There are certain critical parameters that should be kept at the forefront when making the selection for the ideal voltage reference circuit for your system or electronic device.

Initial Accuracy

The initial accuracy of the voltage reference circuit is the variance of the output voltage at 25C.

Long Term Stability

Long term stability of the circuit is a measure of how much the reference voltage would change overtime depending on a number of external and internal variables such as mechanical stress and electrical changes within the circuit.

Thermal Hysteresis

Thermal hysteresis is created when there is a change in the output voltage at a set temperature after a large temperature cycle and this can produce a lot of error in the results.

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