A low-cost direct microwave QAM modulator using silicon MMIC technology

A new method to realize a direct microwave QAM modulator is discussed. The architecture uses SPDT switches and pin diode reflection attenuators to realize a QAM modulator. The attenuators use pin diodes in a forward bias condition to overcome the speed limitation. This slew architecture provides a high speed QAM modulator, and its implementation using Si-MMIC results a cost efficient and high performance modulator for wireless systems.