Three-Bit and Six-Bit Tunable Matching Networks with Tapered Lines

Two tunable matching networks, one with three bits and one with six bits, are designed, fabricated and measured. The tuning elements of the networks are the Radant RMSW-100 SPST MEMS switches. These switches connect fixed line- loading capacitances to the networks. Tapered transmission lines are used instead of uniform lines in the networks. The 6-bit network exhibits two bands with bandwidths of 46% and 29% and Smith Chart coverage of at least 68%. The 3-bit network exhibits a single band with a bandwidth of 44% and a Smith Chart coverage of at least 23%. A particular load is included in the bandwidth and coverage calculations if (a) it can be matched with a reflection of less than -10 dB and (b) the S-parameters of the tunable matching network when configured to match this load satisfy |S₁₁|² + |S₂₁|² ges 0.5, i.e., its measured efficiency is higher than 50%.