Microchip Technology

The UM4300 and UM7300 series combine a diode chip of extremely thick intrinsic region with a low thermal resistance construction. This results in diodes uniquely applicable to very low distortion linear attenuators and specialized functions. The UM4300 series, with large cross-sectional chip area offers the highest power capability, of the two series. The UM7300 series offers lower capacitance.

The UM9301 PIN Diode utilizes special overall chip geometry with an extremely thick intrinsic "I" region, to offer unique capabilities in both RF switch and attenuator applications. The UM9301 is optimal for switch applications when little or no bias voltage is available.

With high isolation, low loss, and low distortion characteristics, this ceramic package PIN diodes are perfect for two-way radio antenna switch applications where size and power handling capability are critical. Its advantages also include the low forward bias resistance and high zero bias impedance that are essential for low loss, high isolation, and wide bandwidth antenna switch performance. Its square design makes this device ideal for use with automatic insertion equipment

The UM9441 is an axially leaded device constructed by metallurgically bonding the PIN chip in between two molybdenum refractory pins that are typically 0.125 inches in diameter and 0.050 inches long. Hyper-pure glass is then fused over this bond to form a void less seal.

These series of PIN diodes were developed for shunt mount applications in microstrip circuits. Good switch performance is demonstrated at frequencies from UHF to 4 GHz and higher.

The UM9701 PIN diode was designed for low resistance at low forward bias current and low reverse bias capacitance. This unique Microsemi design results in both forward and reverse bias. These PIN diodes are characterized for low current drain RF and microwave switch applications particularly for digital filter switch designs.

The UM4000 series features high power PIN diodes with long carrier lifetimes and thick I-regions. They are especially suitable for use in low distortion switches and attenuators, in HF through S band frequencies. While both series are electrically equivalent, the UM4900 series have higher power ratings due to a shorter thermal path between the chip and package. High charge storage and long carrier lifetime enable high RF levels to be controlled with relatively low bias current. Similarly, peak RF voltages can be handled well in excess of applied reverse bias voltage.

The PIN diode series was designed to provide ultra low magnetic PIN diodes for in bore surface coil applications associated with higher field strength (3T and greater) MR scanners. These PIN diodes produce the minimum artifacts (magnetic field distortions) available in the industry, today. The diodes have been tested in magnetic fields of ±7 Tesla.

The UMX9989AP is the first MRI switching diode module, designed to optimize performance and reduce assembly labor, cost, and polarity errors. There are two principle applications for which the UMX9989AP modules are intended: 1) MRI receiver protection from high RF energy fields, including long RF pulses and RF spike pulses present in most MRI machines. The UMX9989AP acts as a passive protector (limiter) for the MRI receiver’s LNA. The diode assembly exhibits extremely low insertion loss, both in the "on" state (high power present) and the "off" state (receiver power present) so the Receiver’s Noise Figure is not increased by the protector circuit. 2) Passive switching of surface coil detuning and blocking circuits. In this case, the flow of loop current during transmitter pulse turns on the diodes, without a switch driver.