Gain enhancement techniques for CMOS LNA and mixer

Abstract

Two major techniques for gain improvement of the CMOS low noise amplifier (LNA) and mixer are presented. First, the inductive interstage matching is applied to design a cascode amplifier for increasing the power transfer between the common source (CS) and common gate (CG) stages. Second, a super source follower (SSF) is utilized in a P-type micromixer for increasing the conversion gain of the mixer. A series of investigations are performed for demonstrating the feasibilities of the proposed techniques. The LNA and mixer designs based on the proposed techniques are realized using 0.35 im IP4M CMOS technology. Then their measured results are compared with those of a preliminary design, which fully integrates a conventional cascode amplifier and a P-type micromixer. The gain of the LNA is increased 2.1 dB and the noise figure is maintained at the same value of the preliminary design. On the other hand, the conversion gain of the super source follower (SSF) of the micromixer output is improved about 9.5 dB. Such improvements reveal great potential of the proposed design techniques on the gain enhancement for the LNA and mixer. Then, the measured results of the preliminary design show the return-loss of 25 dB, the isolation of better than 30 dB, and the conversion gain of 4.8 dB in the 2.4 GHz ISM hand. (C) 2006 Wiley Periodicals, Inc.