Category: The Bipolar Transistor

The Bipolar Transistor

Common Collector Circuit

Common Collector Circuit

Common collector configuration, also known as an emitter follower. This diagram shows an NPN transistor circuit. A common collector circuit (above figure) operates with the collector at signal ground. The input is applied at...

Common Base Circuit

Common Base Circuit

Common base configuration. This diagram shows an NPN transistor circuit. As its name implies, the common base circuit (above figure) has the base at signal ground. The dc bias is the same as for...

Common Emitter Circuit

Common Emitter Circuit

Common emitter configuration. This diagram shows an NPN transistor circuit. A transistor can be hooked up in three general ways. The emitter can be grounded for signal, the base can be grounded for signal,...

Gain versus Frequency

Gain versus Frequency

Alpha cutoff and gain bandwidth product for a hypothetical transistor. Another important specification for a transistor is the range of frequencies over which it can be used as an amplifier. All transistors have an...

Biasing for Amplification

Biasing for Amplification

Three different transistor bias points. The most amplification is obtained when the bias is near the middle of the straight-line portion of the curve. Because a small change in IB causes a large variation...

Biasing

Biasing

At A, the dual-diode model of a simple NPN circuit. At B, the actual transistor circuit. Imagine a bipolar transistor as consisting of two diodes in reverse series. You can’t normally connect two diodes...

NPN versus PNP

NPN versus PNP

THE WORD TRANSISTOR IS A CONTRACTION OF “CURRENT-TRANSFERRING RESISTOR.” A BIPOLAR transistor has two P-N junctions. There are two configurations: a P-type layer sandwiched between two N-type layers, or an N-type layer between two...