It’s just a fact of life. A BJT wired in common emitter, even after compensating for the effects of device and temperature variations, still isn’t a perfect current source. Figure 1 Current mirror ...

Recently (5/21/25), I published a Design Idea (DI) describing a bidirectional current mirror using just two transistors and a diode, “A two-way mirror—current mirror that is.” That circuit works well ...

Circuit and system design requirements often mean compromises. For example, optoisolators are used almost everywhere, but they are highfrequency limited. This simple circuit allows for wider bandwidth ...