DIODES JAN1N78CMR
1N78CMR-JAN

SILICON POINT CONTACT MIXER DIODES - Datasheet

FEATURES

· High Bumont resistance
· Low noise Figure , even in the Starved L.O Mode
· Hermetically Sealed

DESCRIPTION

Alpha’s point contact mixer diodes are designed for applications through Ka-band (40Ghz).
These diodes employ epitaxial silicon optimized for low noise figure and uniformity.
They are available in a variety of packages which make them suitable for use in waveguide, coaxial and stripline applications.
For those applications requiring guaranteed power handling capability, Alpha has diodes that are screened 100 % using narrow RF pulses (/5 nanoseconds).
This screening insures reliable operation at power levels up to in the screened value.
These diodes are particularly useful in applications where the mixer follows a TRL or solid state limiter.  Diodes in packages other than those shown are also available.

APPLICATIONS

These diodes are categorized by noise figure at frequencies up through40GHz.
Matched pairs of mixer diodes are used in conjunction with a hybrid or magic-tee primarily for suppressing noise originating in the local oscillator arm from the signal arm, thus minimizing radiation and absorption of signal power. Other uses are for specific reflection of signals through the hybrid and for balanced modulators and discriminators.

The matching criteria for mixer diodes are as follows :

a. Conversion loss (within 0.3 d of each other)
b. IF impedance (within 25 ohms of each other)
c. The VSWR of individual diodes, when not otherwise restricted (such as 1.3 on premium units) , is limited to 1.6 Max.

These specifications allow the noise figure of the receiver to deteriorate no greater than  0.1 dB due to local oscillator noise . The VSWR limit allows a maximum of 5 % leakage. In practice, this leakage is generally less than 2%.

Matched diodes are supplied in either forward pairs (M) or forward / reverse pairs (MR). The forward/reverse pair allows for a simpler IF circuit design.

MAXIMUM RATINGS

Operating Temperature	-55°C to +150°C
Storage Temperature	-65°C to +150°C
Power Dissipation DC	100 mW