The output resistance of the current source (mirror) is used as active load in place of large-values collector resistance which cannot be fabricated conveniently on a chip. PNP Current Mirrors The Basic Current Mirror with PNP Transistors All of the current mirror circuits presented in previous pages in this group have used NPN transistors. Here, we are calculating the DC voltages (bias voltages) at every node of our circuit. If T1 consists of m transistors and T2 of n transistors, then the output current will be n/m times the input current, as shown in Figure 2b. These current mirrors can be made with NPN or PNP transistors. Let Q2 be a single PNP. The current mirror circuit gains its name because it copies or mirrors the current flowing in one active device in another, keeping the output current constant regardless of loading. In this technique, the circuit is designed in such a way that it copies the current through one active device to another active device with current control feature. BJTs are current-controlled transistors that allow for current amplification. By forming T2 with n transistors connected in parallel, the output current will be n times the input current, as shown in Figure 2a. Sep 13, 2017 Schematic Diagram. Characteristics of MOSFET Current Mirrors. 1 shows the basic npn current mirror. 1) that accepts an input current at the input terminal and provides a "mirrored" current source or sink output at the output terminal. Education.

It makes sense that the bases would share a common voltage with Q1's collector, but the text states "You 'program' the mirror by sinking a current from Q1's collector." In this configuration, the gate-source voltage, V GS, is about 1.2V. An important feature of the current mirror is a relatively high output resistance which helps to keep the output current … That means IREF must … PNP Current Mirror - Free download as Word Doc (.doc), PDF File (.pdf), Text File (.txt) or read online for free.

It may be used as a Wilson current source by applying a constant bias current to the input branch as in Fig. In the attachment you can see a PNP current mirror circuit from AoE.

The proportionality is based on the ratio between R1 and R2 (R sense in your circuit). The upper current mirror produces a current at the collector of Q1 that is a fraction of the load current. The mirrored current is a precise copy of the input current. print (v2#branch/50e-06) Results: … The current being mirrored can be a constant current, or it can be a varying signal dependent upon the …

Figure 2. For its analysis, we assume identical transistors and neglect the Early effect, i.e.

This makes the saturation current ISand current gain βindependent of the collector-base voltage VCE. Scribd is the world's largest social reading and publishing site. Search Search PNP Current Mirror Home. Thread starter krlngc; Start ... that density should be near the BJT's highest beta. The ZDS1009 current mirror has been developed specifically for high side, current sense plus level translation applications and as such will find a broad applications base including battery charge management, DC motor control and over current monitoring functions. Before we talk about the differences between NPN and PNP transistors, we will first discuss what they are and their similarities.

This current produces a voltage across R5 that is proportional to the load current. Difference Between an NPN and a PNP Transistor. A Wilson current mirror is a three-terminal circuit (Fig. Fig. Relevant source code lines: OP print all * Output current over constant input current (with 1V load): should be 1 for best match. 2. Current Mirrors Basic BJT Current Mirror Current mirrors are basic building blocks of analog design. Forums. AIC-1.3.2: Current Mirrors -- Lateral PNP Current Mirror. Then Q4 should be 10 PNP of that size in parallel. Homework Help PNP Current Mirror. In this, the current is flowing through one device can be copied into another device but in inverting form. Just as we connected collector to base with bipolar junction transistors, we can connect drain to gate of a MOSFET to cause the device to operate as a forward-biased diode. The resistor on Q2 remains 6.6K, Q4's resistor changed to 660.

we assume VA→∞. This is by no means necessary; as shown to the left, we can easily use PNP transistors to build current mirrors. SPICE Simulations Operating Point Analysis. Both NPN and PNP are bipolar junction transistors (BJTs). Let Q1 = Q4 = 10 Q2, and also put 660 ohms on its emitter.

The Current Mirror is a widely popular technique for monolithic IC design. A current mirror is a circuit block which functions to produce a copy of the current flowing into or out of an input terminal by replicating the current in an output terminal. We can easily use enhancement mode MOSFETs to form current mirrors, as shown in the circuit to the right.