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Mixer and Clamping Diodes
Specification Selection Guide
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[1] typical series resistance (Rs) value.
[2] measured at If = 100 mA.
Glossary
Breakdown voltage (Vbr)
- What:
- the voltage a Schottky barrier diode can tolerate before being damaged.
- Goodness:
- In clamping applications, breakdown voltage only matters if an anti-parallel pair isn't used (most people use a pair), then a higher breakdown voltage is (usually) better, at the cost of increased Rs (current carrying capacity).
Maximum Capacitance (CT)
- What:
- The total capacitance associated with the diode, equal to the junction capacitance Cj plus any other parasitic capacitance such as package parasitic capacitance.
- Goodness:
- lower is better
- Low capacitance is required for good isolation in a series switch.
- Low capacitance also implies a low loss switch in the shunt configuration.
Dynamic Resistance of a Schottky Diode (RD)
- What:
- Schottky diode resistance may be expressed as a dynamic resistance RD or as a series resistance Rs. These two terms are related by the equation RD = Rs + Rj, where Rj is the resistance of the junction. Junction resistance of a diode with DC bias is quite accurately calculated by: Rj = 26/Ib where Ib is the bias current in milliamperes. Either resistance is a measure of the "loss" in the diode.
- Goodness:
- lower is better.
Forward Voltage (Vf)
- What:
- The voltage at which a Schottky barrier diode starts to clip.
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