This performance is achieved through the use of hybrid MIC designs that incorporate PIN
diode limiter circuitry and Enhancement mode GaAs pHEMT semiconductor devices.
The receiver consists of a switch,
diode limiter, two low noise amplifiers (LNA), two bandpass filters, a down-convert mixer and two low pass filter.
The diode limiter is the only completely self-contained passive receiver protector technology.
The passive all-solid-state diode limiter is normally the desired solution for most receiver protector applications.
When the required power handling exceeds a diode limiter's capability and fast recovery time is needed, one possible solution is to place a pre-T/R tube in front of the limiter.
Depending upon actual conditions, it may be possible to design a diode limiter that can handle the normal power successfully even though it cannot tolerate the overload.
The traditional receiver protector structure is composed of a pre-T/R tube, a T/R tube and a diode limiter. The T/R tube has an inherently long recovery time.
This protection comes in the form of a solid-state PIN diode limiter. The limiter is mounted before the low noise gain stage and will provide a maximum output power under both spike and flat leakage conditions that will not damage the amplifier.
Using a PIN diode limiter is not without consequence.
It will be quite some time before MMIC limiters will be able to replace the 50 W silicon PIN diode limiters. At the present time, it is possible to realize a 10 W PIN diode limiter or a 1 W Schottky barrier diode limiter, whereas in the hybrid form PIN diode limiters up to 400 W have been realized.
Lehmann, "Monolithic MBE-Grown GaAs PIN Diode Limiter," 1987 IEEE Microwave and mm-Wave Monolithic Symposium, pp.
In existing radar systems, silicon PIN diode limiters are utilized in the T/R modules.