The simple two transistor implementation of the current mirror is based on the fundamental relationship that two equal size transistors at the same temperature with the same V GS for a MOS or V BE for a BJT have the same drain or collector current. Current mirrors on a chip are made with well-matched transistors and usually no emitter resistors, and have a different set of tradeoffs. A proper current mirror circuit can be characterized using three specifications. emitter resistors might be 100Ω.
It is given by rout= ric2 which can be much greater than r02. Derive a symbolic expression for the output resistance r
One from the emitter of transistor "2" and the collector of the current mirror transistor and one from the emitter of "3" to the collector of the current mirror.
4. The Red Probe will show the current of Q1 transistor in simulation.
T3 acts as a regulating valve which increases the current through the current mirror as Input A gets more power while T4 kind of does the opposite by draining current from the mirror with increasing input B power. T1 and T2 are PNP transistors and form together a current mirror. A current mirror is a circuit, which ... loop formed by the 2 base-emitter voltages and the voltage drops across the 2 emitter resistors, respectively. The implementation of the current mirror circuit may seem simple but there is a lot going on. Current Mirrors I Objective: This lab introduces the concept of current mirrors. Transistor Q 1 is diode connected, which is to say its collector-base voltage is zero. In the classical current mirror the emitters of the transistors are grounded (no emitter resistors). VB1=VB2( The base of two BJT's are connected to each other). Current mirror as differential amplifier. A current mirror circuit has lots of primary and secondary dependencies and that is the main concern to characterize current mirror circuit.
In the Widlar current mirror there is a resistor only in the emitter of the output transistor. I made the current mirror also with R1=150R so I=28mA, but then the current in R3 is as follow with different … Another way to provide different current magnitudes at different mirror outputs is to change the areas of the transistor emitters. I want to make a current mirror. I did do some simulations and that works, but when I make a real current mirror this does not work. 1. Basically, the current thru each side is inversely proportional to each's emitter resistance. Ask yourself what happens if you add two resistors. With these resistors, Rte2 is no longer zero so that the output resistance is increased. Or more simply, add two emitter resistors to … Pre-lab assignment. Current Transfer Ratio. BJT Mirror with Base Current Compensation Figure 3 shows the basic current mirror with a third transistor added.
This is the popular current mirror circuit with 2 EMITTER DEGENERATION RESISTORS R1 and R2. However, we can put resistors in all of the emitter circuits, or we can use the cascode mirror configuration. As you can see. Figure 4 shows the small-signal circuit equivalent to Figure 3. 2. Current mirror circuits are widely used, especially within integrated circuit technology. Figure 3 shows a bipolar current mirror with emitter resistors to increase its output resistance.