BB156,135

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Variable Capacitance diodes, also widely referred to as Varicaps, Varactors, or tunable capacitors, are widely used in a number of different applications due to their unique ability to control of a voltage or current by changing their capacitance. The BB156/135 types of Variable Capacitance Diode (VCD) is a particularly robust and well-suited option for a wide range of applications, from radio and television tuners, to power supplies. This article aims to explore the applications and working principles of the BB156/135 VCD.

Applications of the BB156/135 Variable Capacitance Diode

The BB156/135 Varicaps are widely used for hardware controlling, for example, in radio and television tuners, as the device can control switch tuning or memory switching. The diode’s highly accurate, low cost and its low noise make it particularly suitable for controlling radio frequency circuits. Modulating radio receivers, such as AM and FM receivers, use this type of diode because it can switch large amounts of power while keeping within the requirements of their output level. Not only are Varicaps suited for the modulation of radio receivers, they are also used in the demodulation of transmission signals, as a coil may be inserted into the antenna that allows the incoming signal to modulate the voltage on the diode’s gate. As a result, the diode’s capacitance changes in accordance with the modulation envelope of the received signal. Varicaps can also be used in the selection of frequencies in a bandpass filter, or for fine adjustment of an oscillator\'s frequency.

Additionally, the BB156/135 Varicaps can work as a voltage stabilizer in power supplies, adjusting the voltage to a stable value. It can also be used in the kickstart regulation, where the diode’s capacitance will be regulated to achieve stabilization. The diode can touch the precision trimming of amplifiers and filters as well, due to its high precision performance and low noise levels.

Working Principles of the BB156/135 Variable Capacitance Diode

The working principle of a Varicap is based on a quantum process of electron tunneling, which is a quantum mechanical phenomenon that occurs when electrons cross through a barrier. In this case, the barrier is the junction between the diode’s cathode and anode. The voltage across the diode will be determined by the total capacitance, which is affected by the number of electrons that tunnel across the junction. When a bias voltage is applied to the diode, the rate of electrons that tunnel across the junction increases, which in turn increases the total capacitance of the diode. This can cause the total capacitance of the diode to vary between a few pF to several hundred pF, depending on the applied voltage.

When using the BB156/135 VCD, the output frequency is adjustable by tuning the diode’s capacitance. Its capacitance range, the DC bias voltage on the diode, and the type of oscillator circuit being used, will greatly affect the total output frequency range. Varicaps are used in voltage-controlled oscillators, frequency multipliers, and frequency dividers. As a result, the variable capacitance diodes can be precisely tuned for any frequency range.

Conclusion

The BB156/135 Variable Capacitance Diode is a particularly robust and versatile VCD, applicable to a wide range of applications from radio and television tuners, to power supplies. Its operation is based on a quantum process of electron tunneling, allowing for precise adjustment of tuning frequencies and voltages. Despite its common use in radio and television tuners, the diode displays a versatility that makes it suitable for power supplies, filter selection and amplifier tuning.

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