• Bipolar transistors are constructed of a three-layer semiconductor “sandwich” either PNP or NPN. As such, transistors register as two diodes connected back-to-back when tested with a multimeter’s “resistance” or “diode check” function as illustrated in the figure below. Low resistance…

  • Bipolar junction transistors (Also known as BJTs) can be used as an amplifier, filter, rectifier, oscillator, or even a switch, which we cover an example in the first section. The transistor will operate as an amplifier or other linear circuit…

  • The invention of the bipolar transistor in 1948 ushered in a revolution in electronics. Technical feats previously requiring relatively large, mechanically fragile, power-hungry vacuum tubes were suddenly achievable with tiny, mechanically rugged, power-thrifty specks of crystalline silicon. This revolution made…

  • The SPICE circuit simulation program provides for modeling diodes in circuit simulations. The diode model is based on characterization of individual devices as described in a product data sheet and manufacturing process characteristics not listed. Some information has been extracted…

  • Varicap or varactor diodes A variable capacitance diode is known as a varicap diode or as a varactor. If a diode is reverse biased, an insulating depletion region forms between the two semiconductive layers. In many diodes the width of…

  • Schottky diodes Schottky diodes are constructed of a metal-to-N junction rather than a P-N semiconductor junction. Also known as hot-carrier diodes, Schottky diodes are characterized by fast switching times (low reverse-recovery time), low forward voltage drop (typically 0.25 to 0.4…

  • What Is a Zener Diode? A Zener diode is a special type of rectifying diode that can handle breakdown due to reverse breakdown voltage without failing completely. Here we will discuss the concept of using diodes to regulate voltage drop…

  • Diodes can perform switching and digital logic operations. Forward and reverse bias switch a diode between the low and high impedance states, respectively. Thus, it serves as a switch. Logic Diodes can perform digital logic functions: AND, and OR. Diode…

  • A popular use of diodes is for the mitigation of inductive “kickback:” the pulses of high voltage produced when direct current through an inductor is interrupted. Inductive Kickback without Protection Take, for example, this simple circuit in the figure below…

  • A voltage multiplier is a specialized rectifier circuit producing an output which is theoretically an integer times the AC peak input, for example, 2, 3, or 4 times the AC peak input. Thus, it is possible to get 200 VDC from…

  • The circuits in the figure below are known as clampers or DC restorers. The corresponding netlist is also in the figure below. These circuits clamp a peak of a waveform to a specific DC level compared with a capacitively coupled…

  • A circuit which removes the peak of a waveform is known as a clipper. A negative clipper is shown in the figure below.  Clapper Circuit Operation Analysis This schematic diagram was produced with Xcircuit schematic capture program. Xcircuit produced the…

  • A peak detector is a series connection of a diode and a capacitor outputting a DC voltage equal to the peak value of the applied AC signal. Peak Detector Operation Analysis The circuit is shown in the figure below with the…

  • What is Rectification? Now we come to the most popular application of the diode: rectification. Simply defined, rectification is the conversion of alternating current (AC) to direct current (DC). This involves a device that only allows one-way flow of electric…

  • In addition to forward voltage drop (Vf) and peak inverse voltage (PIV), there are many other ratings of diodes important to circuit design and component selection. Semiconductor manufacturers provide detailed specifications on their products—diodes included—in publications known as datasheets. Datasheets…

Join 900+ subscribers

Stay in the loop with everything you need to know.

Sign up