Single Diode Configuration: Gallium Arsenide PIN diodes offer improved performance characteristics over silicon in many microwave semiconductor applications These benefits result from the intrinsic semiconductor properties of GaAs. Its inherent high carrier mobility results in a low resistance fast switching device. The low carrier concentration in the I region layer produces a near zero punch through bias voltage. Gallium Arsenide's high band gap also assures it will operate at high operating temperatures. Switching speeds in the low nanosecond range using an inexpensive TTL buffer logic is attainable with GaAs PIN diodes. This performance can be achieved because GaAs PIN diodes exhibit high impedance at a positive bias (up to .5V). Reverse bias is not required for many GaAs PIN diode applications. Low loss, in switch and phase shifter circuits at frequencies up to 40 GHz is possible as a result of low parasitic series resistance in the conducting and non-conducting states.