An empirical I-V curve for a real current source would be obtained using the load-switching method. Let's start with one of the more familiar ideal components: the resistor.

We will be looking at the I-V curve of a Zener diode in a future article.

The magnitude of the current is constant, but two horizontal lines are needed because the direction of the current changes depending on whether the voltage is moving from V1 to V2 or V2 to V1. Thanks for the explanation, it makes sense now. If you substitute for V accordingly, you will find that the blue curve equation (bottom) reduces to $$I_{min} = \frac{\Delta t}{2L(V_1-V_2)} \times -V_{2}^{2}$$.

The equation given is for the entire curve. The Zener diode is a non-linear, passive device that is used as a voltage regulator when it is operated in reverse bias. Based on their basic definitions, we can derive the I-V curves of ideal passive components (resistors, capacitors, and inductors) using the concept of linear voltage sweeps. But when the voltage crosses the time axis, the positive area under the curve starts to balance out the negative area under the curve, and this causes the current magnitude to decrease toward zero. More specifically, many non-linear devices such as diodes and transistors are used in operating regions in which they behave like ideal components—such as current sources, voltage regulators, and resistors. The colour of the graph corresponds to either a positive slope or a negative slope.

In a future article, we will look at I-V curves of non-linear devices. Biomedical Applications: A New Series of Single-Use Liquid Flow Sensors from Sensirion, Design a Control Board for a Romi Robot Chassis, Using Operational Amplifiers as Comparators, Op-Amps as Active Band-Pass and Active Band-Reject Filters.

For devices that do not supply power, I-V curves are obtained by using linear voltage sweeps. Keep up the good work. We will use the concept of load switching for the I-V curves of an ideal voltage source and an ideal current source. Load switching techniques are used to measure the I-V characteristics of devices and circuits that supply power, such as voltage regulator circuits, solar cells, and batteries. The voltage across an inductor is the product of inductance and the rate of change of the current flowing through the inductor: This means that the current is proportional to the integral of voltage, and this is what we see in the following plots. It is a device that has three terminals, with high power and frequency which is vertically oriented. When the voltage changes from a positive slope (shown in blue in Figure 5) to a negative slope (orange), the direction of the current reverses; this is represented in the current vs. time plot as a change from the positive-current section of the graph to the negative-current section of the graph. When positive cycle of an AC signal passed through an Inductor, current flow increases. Don't have an AAC account? In general, if the device requires power to operate, the voltage sweep method is used. The direction of the current is negative as the voltage moves from V1 to V2 and positive as the voltage moves from V2 to V1. Note the difference between the capacitor and the inductor: With a capacitor, current is proportional to the derivative of voltage, and thus a linear voltage sweep translates to constant current. The I-V curve for an ideal current source is a straight line parallel to the X-axis (see Figure 4). This article discusses I-V curves for passive components, voltage sources, and current sources. The I-V relationship of an ideal inductor is shown in Figure 8. Thank you for pointing it out, I've made the change. In the case of a capacitor, the current through the capacitor at any given moment is the product of capacitance and the rate of change (i.e., the derivative with respect to time) of the voltage across the capacitor. In other words, a 5A ideal current source would deliver exactly 5A to a 1Ω load resistor or to a 1 kΩ resistor, even though the second resistor would generate a voltage drop of 5000V! These include terms such as the curie temperature, the inductor's DC resistance (DCR), electromagnetic interference, and magnetic saturation flux density. Also, a MOSFET operating in the saturation region exhibits behavior similar to that of a (voltage-controlled) current source. If the value of the resistor is $$10k\Omega$$, then the current drawn by the resistor from the voltage supply will be dictated by Ohm's law, which is $$ I = \frac{V}{R} = \frac{10V}{10k\Omega} = 1mA$$. Similarly for the maximum current. This is highly impractical but, nonetheless, ideal current sources are useful tools in circuit analysis. Because devices can operate with small values of resistance (1-10Ω) as well as large values of resistance (10-1000kΩ), the resistors are varied logarithmically, i.e., from 10 to 100 to 1000 and so on. We know Inductor hates change in current so it develops a Induced voltage to act against the current flow that’s causing it. Therefore, the I-V curve for an ideal voltage supply will be a straight line parallel to the Y-axis (see Figure 3). Figure 1.1 illustrates the translation of voltage sweep with respect to time (V vs t) onto the X-axis of the current-voltage graph (I vs V). Because time on the x-axis increases, $$\Delta t = t_2 - t_1$$ is a positive quantity. For these devices, I-V curves are obtained by load switching. If you have a device that supplies voltage or current, such as a battery or a solar panel or a regular power supply, you cannot change the voltage across the device, because there is a specific voltage or current being generated by the device. I love this site. Though "current supplies" are not nearly as common as voltage supplies, many analog transistor circuits are biased using a constant-current source.

Observe in the input voltage sweep that $$V_1$$ is positive and $$V_2$$ is negative, therefore, $$(V_1-V_2)$$ is a positive quantity (rising slope), and $$V_{2}^{2}$$ is a squared term, which is always positve.

The load is the device that electrical power is being delivered to, where power is defined as $$P = V \times I$$.

The current that is supplied by the power supply is measured by an ammeter for each value of load resistance—shown in Figure 1.2(b)—and the voltage across the load is measured using a voltmeter—shown in Figure 1.2(c).