Bidirectional Mosfet Switch Board

Introducing our next-generation Bidirectional MOSFET Switch, completely redesigned from the ground up for ultra-fast, high-frequency AC circuit experimentation. This new revision focuses on minimizing gate-loop inductance, incorporates a brand-new high-speed gate driver, and adds several practical features for demanding laboratory and research applications. Here’s why this upgraded bidirectional switch is an essential tool for advanced experimentation:

• Bidirectional Current Blocking: Using two MOSFETs in a back-to-back (common-source) configuration, the switch blocks current flow in both directions when turned off. This overcomes the body-diode limitation of single MOSFETs and makes the board ideal for AC systems where current alternates direction.
   
• Ultra-Fast Switching: The new gate driver enables switching transitions just above 10 ns (MOSFET- and load-dependent). This allows rapid connection and disconnection of inductors, capacitors, and other reactive components, and precise manipulation of tank and resonance circuits.
   
• Low Gate-Loop Inductance Layout: The PCB layout has been fully reworked to minimize gate-loop inductance, resulting in cleaner edges, reduced ringing, and more stable operation at high frequencies.
   
• Ideal for Resonance Circuits: True bidirectional current blocking makes this switch indispensable in resonant AC systems, where current must flow alternately in both directions without distortion.
   
• Robust Isolated Driver System: Like our standard MOSFET Switch Board, this model uses isolated gate drivers powered by an onboard DC-DC converter. This allows the MOSFET pair to operate at up to 2300 V potential difference relative to the control electronics.
   
• High-Side or Low-Side Switching: The flexible topology allows the board to be used in both high-side and low-side switching configurations, depending on your circuit requirements.
   
• 3.3V & 5V Logic Compatible: The input stage supports both 3.3 V and 5 V logic signals, enabling direct connection to microcontrollers for programmable and automated switching control.
   
• Selectable 50-Ohm Input Termination: A switchable 50 ohm impedance-matching resistor is included on the input, which is highly beneficial for clean signal integrity when operating at high frequencies with standard signal generators and coaxial cabling.
   
• Built-In Fuse Protection: An onboard fuse provides additional protection in the event of overcurrent or fault conditions, helping to safeguard both the MOSFETs and the gate driver circuitry.
   
• Fan Support for High-Frequency Operation: The board provides a dedicated 12 V fan output via two XH2.54 connectors as well as a 2-port screw terminal. For prolonged operation above 1 MHz, we recommend using the optional 12 V Auxiliary Fan, which plugs directly into the board and provides effective airflow over both the MOSFETs and the PCB.
   
• High-Frequency Capability: While the achievable speed depends on MOSFET gate capacitance and load conditions, the board comfortably supports frequencies above 1 MHz and has been tested at 3 MHz and beyond with suitable devices.
   
• User-Friendly High-Current Connections: Heavy-duty screw terminals rated for high current and AWG 10 wire ensure secure, low-loss connections for demanding AC switching applications.
   
• BNC Input for Convenience: A dedicated BNC connector provides a clean, reliable connection to function generators and laboratory signal sources.
   
• Input Signal Compatibility: Designed for square-wave input signals in the 3.3 V to 5 V range (into 50 ohm when selected). Negative input voltages must be avoided to protect the gate driver.

Whether you are modifying resonant tank circuits or performing advanced high-frequency AC switching experiments, this next-generation bidirectional MOSFET switch delivers exceptional performance, robustness, and precision.

Technical Specification:

Datasheets for the selectable MOSFETs can be found here: TK125N60Z1—MSC060SMA070B—G3R160MT12D—SCTW40N120G2V—MSC035SMA170B

Note: Best-case switching times refer to light capacitive discharge; typical values reflect heavier load operation. Speed is primarily determined by MOSFET gate capacitance, supply impedance, and load conditions — not the board itself.

When operating at the upper end of the board’s switching frequency capability, additional forced-air cooling may be required. For this purpose, an optional top-mount fan stand is available that holds our 12 V, 80 mm auxiliary cooling fan above the MOSFET switch board and directs airflow downward onto the components most affected by thermal stress during ultra-fast switching, including the MOSFETs. This cooling arrangement extends the board’s usable operating range at very high frequencies and reduces the risk of thermal shutdown when running close to maximum switching performance. Both the top-mount fan stand and the 12 V, 80 mm auxiliary cooling fan are offered as optional extras and are compatible with all of our MOSFET switch boards.

This product includes two heat sinks for TO-247-sized MOSFETs and a BNC to hookup wire adapter for easy connection to a Microcontroller Unit (MCU).