Infineon BAT15-099R Schottky Diode: Key Features and Application Circuit Design

The Infineon BAT15-099R is a silicon Schottky barrier diode specifically engineered for high-frequency applications. As a surface-mount device (SMD) in a compact SC-79 package, it is an ideal choice for modern electronic designs where space efficiency and high performance are critical. Its unique properties make it indispensable in RF and microwave circuits, such as mixers, detectors, and samplers.

Key Features

The standout characteristics of the BAT15-099R stem from its Schottky barrier construction. Unlike standard PN-junction diodes, a Schottky diode has a metal-semiconductor junction, which provides several distinct advantages:

Low Forward Voltage (Vf): The diode exhibits a very low forward voltage drop, typically around 350 mV at 5 mA. This minimizes power loss and improves efficiency in rectification and signal detection applications.

Ultra-Fast Switching Speeds: The majority carriers (electrons) are responsible for conduction, meaning there is no slow reverse recovery time associated with minority carrier recombination. This makes it exceptionally fast, which is crucial for high-frequency operation up to several GHz.

Low Capacitance: The device features a very low parasitic junction capacitance, typically 0.6 pF at 0 V, 1 MHz. This is vital for RF applications, as high capacitance would shunt high-frequency signals to ground, degrading circuit performance.

Series Pair Configuration: The BAT15-099R integrates two independent diodes in a common cathode configuration within a single package. This is extremely beneficial for designing balanced circuits, such as double-balanced mixers, saving board space and ensuring closely matched characteristics for superior performance.

Application Circuit Design: A Balanced Mixer Example

One of the most common applications for the BAT15-099R is in the design of a double-balanced mixer (DBM), a core component in communication systems for frequency conversion.

Circuit Operation:

A typical double-balanced mixer circuit uses a center-tapped transformer to split the Local Oscillator (LO) signal and the BAT15-099R diode pair. The Radio Frequency (RF) input is applied to the center tap of the transformer's secondary winding.

1. The LO signal, which is a high-power sinusoidal wave, drives the diodes alternately into conduction and cutoff.

2. When the LO voltage is positive, one diode conducts, and when it is negative, the other conducts. This effectively acts as a polarity-switching circuit.

3. This switching function multiplies the RF input signal with the LO signal. The output at the Intermediate Frequency (IF) port contains the sum (LO+RF) and difference (LO-RF) frequencies.

4. The balanced nature of the circuit provides excellent suppression of the original LO and RF signals at the IF output, leaving primarily the desired mixed products.

Design Considerations:

Impedance Matching: For maximum power transfer, the RF input, LO port, and IF output must be impedance matched, typically to 50 Ω, using matching networks. This minimizes signal reflections.

LO Drive Level: Schottky diode mixers require a sufficient LO drive level to fully switch the diodes on and off. The BAT15-099R is optimized for this, but the drive level must be calculated to ensure proper operation without damaging the diodes.

Biasing (if used): While often operated without DC bias, a small bias current can sometimes be applied to lower the LO power requirement or to optimize the operating point for specific metrics like conversion loss or intermodulation distortion.

ICGOOODFIND

ICGOOODFIND: The Infineon BAT15-099R Schottky diode pair is a superior solution for high-frequency circuit design. Its ultra-low capacitance and fast switching speed make it a cornerstone component in critical RF applications like mixers and detectors, enabling the development of efficient, compact, and high-performance modern communication systems.

Keywords:

Schottky Diode

RF Mixer

High-Frequency

Low Capacitance

Application Circuit