A Highly Linear Wideband CMOS LNTA Employing Noise/Distortion Cancellation and Gain Compensation

A wideband low-noise transconductance amplifier (LNTA) with high linearity is proposed. The differential LNTA adopts complementary common-gate (CG), current mirror (CM) and common-source (CS) schemes to obtain noise and distortion cancellation, and $$g_{m}$$gm-enhancement. A high third-order input intercept point (IIP3) is obtained due to the distortion cancellation and the complementary characteristics of NMOS and PMOS transistors. The gain expansion of the class-AB CS stage compensates the gain compression of the CG---CM stage, which leads to a high large-signal linearity. A wide input matching bandwidth is achieved by utilizing a $$\uppi $$ź-type input matching network without the use of on-chip bulky inductors, and the passive voltage gain of the $$\uppi $$ź-network further enhances the effective transconductance. Designed in a 0.18-$$\upmu \hbox {m}$$μm CMOS process, the simulation results show that it provides a minimum noise figure (NF) of 2.95 dB and a maximum transconductance of 79 mS from 0.1 to 3.6 GHz. An input 1-dB compression/desensitization point and an IIP3 of 8.1/5.59 and 18.14 dBm are obtained, respectively. The NF is degraded by 0.3 dB with a 0-dBm blocker. The circuit draws 10.7 mA from a 2.5-V supply, and the core area is only $$0.5 \times 0.12\,\hbox {mm}^{2}$$0.5×0.12mm2.