Multiplexers using weakly-coupled networks in RF front end circuitry

Multiplexing circuitry comprising:

• a common port, a first port, and a second port;
• filtering circuitry coupled to the common port, the first port, and the second port and configured to provide a first transfer function between the common port and the first port and a second transfer function between the common port and the second port wherein:
• the first transfer function has a first passband and a first stopband;
• the second transfer function has a second passband wherein the first stopband of the first transfer function is within the second passband;
• a first filter path connected between the common port and the first port;
• a first parallel resonant circuit is provided in shunt with respect to a second filter path connected between the common port and the second port;
• and
• a second parallel resonant circuit is provided in shunt with respect to the second filter path wherein the second parallel resonant circuit is weakly coupled to the first parallel resonant circuit such that the first stopband is within the second passband.