Coplanar waveguide directional coupler and flip-clip microwave monolithic integrated circuit assembly incorporating the coupler

A coplanar waveguide directional coupler, comprising:

• a substrate having a surface;
• an input port, a coupled port, a port and an isolation port formed on said surface;
• at least two parallel first striplines formed on said surface and connected between the input port and the direct port;
• at least two parallel second striplines formed on said surface and connected between the coupled port and the isolation port, the second striplines being interdigitated with the first striplines;
• and
• first and second main ground planes formed on said surface and extending lateral to and on opposite sides of said interdigitated first and second striplines;
• in which the spacing S between adjacent first and second striplines is approximately equal to S=N.times.S.sub.1, where S.sub.1 is the spacing between first and second striplines if only one first stripline and one second stripline were provided, and N is the total number of first and second striplines.

A microwave monolithic integrated circuit (MMIC) assembly, comprising:

• a substrate having a surface;
• coplanar waveguide interconnect means formed on said surface of the substrate;
• a MMIC chip having a surface;
• coplanar waveguide interconnect means formed on said surface of the MMIC chip;
• the MMIC chip being flip-chip mounted on the substrate such that said surface of the MMIC chip faces said surface of the substrate;
• interconnect means interconnecting said coplanar waveguide interconnect means of the MMIC chip with said coplanar waveguide interconnect means of the substrate;
• and
• a coplanar waveguide directional coupler formed on said surface of the MMIC chip and being interconnected with said coplanar waveguide interconnect means thereof, the directional coupler including;
• an input port, a coupled port, a direct port and an isolation port formed on said surface of the MMIC chip;
• at least two parallel first striplines formed on said surface of the MMIC chip and connected between the input port and the direct port;
• at least two parallel second striplines formed on said surface of the MMIC chip and connected between the coupled port and the isolation port, the second striplines being interdigitated with the first striplines;
• and
• first and second main ground planes formed on said surface of the MMIC chip and extending lateral to and on opposite sides of said interdigitated first and second striplines.

A microwave monolithic integrated circuit (MMIC) assembly, comprising:

• a substrate having a surface;
• coplanar waveguide interconnect means formed on said surface of the substrate;
• a MMIC chip having a surface;
• coplanar waveguide interconnect means formed on said surface of the MMIC chip;
• the MMIC chip being flip-chip mounted on the substrate such that said surface of the MMIC chip faces said surface of the substrate;
• interconnect means interconnecting said coplanar waveguide interconnect means of the MMIC chip with said coplanar waveguide interconnect means of the substrate;
• and
• a coplanar waveguide directional coupler formed on said surface of the substrate and being interconnected with said coplanar waveguide interconnect means thereof, the directional coupler including;
• an input port, a coupled port, a direct port and an isolation port formed on said surface of the substrate;
• at least two parallel first striplines formed on said surface of the substrate and connected between the input port and the direct port;
• at least two parallel second striplines formed on said surface of the substrate and connected between the coupled port and the isolation port, the second striplines being interdigitated with the first striplines;
• and
• first and second main ground planes formed on said surface of the substrate and extending lateral to and on opposite sides of said interdigitated first and second striplines.