Generic constant phase digital attenuators

This paper describes the implementation of a range of generic GaAs MMIC digital attenuators based on a standard commercially available foundry process. The design of a device for the frequency range 1.5 GHz to 6.5 GHz is described as an example and its application at different frequencies is discussed. A digital attenuator consists of a number of cascaded units each containing individual bits, switched in as required to achieve the desired value of attenuation. These cascaded bits are usually arranged in a binary form with the least significant bit as the minimum resolvable level. The most significant bit determines the range of attenuation