An efficient mm‐wave LNA impedance match synthesis methodology with coordinate descent method

Abstract

AbstractIn this paper, a novel synthesis methodology for LNA impedance matching is proposed, which consists of two main phases: database generation and parameter optimization. In the former phase, a large‐scale sweep of electromagnetic simulations of passive components is performed to speed up parameter optimization. In the latter phase, the coordinate descent method is used as the optimizer of this methodology. Since frequently dozens of parameters need to be optimized in synthesize LNAs, the coordinate descent method can temporarily fix some parameters in each iteration, thus convert the optimization problem into multiple simple low or even one‐dimensional optimizations, which can eventually obtain high‐quality LNAs quickly in fewer descent iterations. This methodology is applied to a Ka‐band two‐stage differential LNA design using 65 nm CMOS technology, and the synthesis time is only 3 min, which is tens of times faster compared to existing synthesis methods. The proposed LNA circuit is fabricated and the measured results verify the feasibility of the synthesis method.