Broad band monolithic cross point switch matrices

A series of broadband monolithic switch matrices has been fabricated. Circuits covering DC to 18 GHz are described, including a 4 to 10-GHz fully monolithic 2 by 2 matrix on a single chip with 4-dB insertion loss and greater than 40-dB isolation. The circuits utilize a high-isolation microstrip crossover. The matrix approach uses orthogonal input and output lines with an independent switching element at each crosspoint. Only a small percent of the input signal is extracted at each crosspoint, so the input line can be continued to drive additional crosspoints. The light coupling from the lines requires the crosspoints to provide gain to prevent excessive insertion loss in the matrix. The switching element uses dual-gate FETs to provide both gain and isolation.<>