WWW . Microsemi . C OM
The UM9989 diode series was designed to protect MRI receivers from high RF energy fields including long RF pulses and RF spike pulses present in most MRI machines. The UM9989 acts as a passive protector (limiter) for the MRI receiver. No forward bias voltage is required to turn on the diode. It is selfbiased by the RF transmitter pulse power. A switch driver is not needed for this receiver protection.
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UM9989
FAST MRI PROTECTION DIODES
DESCRIPTION
KEY FEATURES
WWW . Microsemi . C OM
The UM9989 diode series was designed to protect MRI receivers from high RF energy fields including long RF pulses and RF spike pulses present in most MRI machines. The UM9989 acts as a passive protector (limiter) for the MRI receiver. No forward bias voltage is required to turn on the diode. It is selfbiased by the RF transmitter pulse power. A switch driver is not needed for this receiver protection application.
Receiver protector diodes appear directly across the input port of the receiver. They are connected in anti-parallel pairs to limit the RF carrier excursion in both polarities.
UM9989 Datasheet
