Bi-directional Distributed Amplifier in 0.11 μm CMOS Technology

This paper presents and compares two different design approaches for bi-directional distributed amplifiers (BDDA) in 0.11 μm CMOS technology. Distributed amplifiers (DA) and BDDAs can be designed starting from T-type and π- type unit cells of artificial transmission lines (ATL). This paper presents π- type topology for BDDAs and compares with T-type BDDAs in terms of gain, bandwidth and chip area. Designing DAs and BDDAs with π- type unit cells provide advantages from two different perspectives. Firstly, π- type BDDAs can be designed with more gm - cells than T-type BDDAs with the approximately same chip area. This provides higher gain without the cost of chip area because a π- type unit cell has one less inductor than a T-type unit cell. Secondly, smaller-sized gm - cells can be designed owing to extra active cells in π- type BDDAs in order to increase the bandwidth of BDDAs. Hence, π- type BDDA can provide higher bandwidth with the same gain and the chip area if desired. The simulated gains of BDDA with three T-type and four π- type unit cells are 8.5 dB and 10 dB at 2-19.5 GHz. In addition, BDDA built using π- type unit cells with active cells equivalent to four fully active gm - cells is designed with smaller gm - cells to achieve higher bandwidth. Thus, 8.5 dB gain is obtained over 2-23 GHz. The chip areas are almost the same as the BDDA with three T-type unit cells for all versions of designed π- type BDDAs.