Abstract
This work proposes a novel linearized low noise amplifier (LNA) for X-band applications with flat power gain, low noise performance and enhanced linearity. In this study, a triple-cascode topology with dual-resonant network is utilized and a modified post-distortion network is introduced to improve the linearity. The LNA utilizes a subthreshold auxiliary NMOS transistor to reduce the nonlinearity with low power consumption. In addition, a methodology is proposed to predict the characteristic of the linearity performance of the proposed LNA with modified post-distortion network. With a small increase of 1 mW in power consumption due to the inclusion of the post-distortion network, the input intercept point IIP3 is improved and lies in the range of −3 to +8 dBm over the frequency range from 8 to 12 GHz. Implemented in Global Foundries 130 nm CMOS process, the LNA achieves a peak gain of 18 dB, and a 1.3 dB minimum NF over 8 to 12 GHz. The proposed LNA requires an area of 1.2 mm2 and a power of 18 mW.
Highlights
Growing research space applications and radar systems has aroused interest in broadband low noise amplifier (LNA)
We propose the triple-cascode configuration LNA combined with a post-distortion network to improve the linearity with a simple input matching network and low noise performance
The modified post-distortion network contributes its own noise according to the noise analysis and results in increased noise figure (NF)
Summary
Growing research space applications and radar systems has aroused interest in broadband LNAs. To achieve broadband input matching, band-pass filtering (BPF) network, feedback network, common-gate (CG) stage, and inductive source degeneration techniques have been proposed [1,2,3,4]. A derivative superposition (DS) method [9] uses an additional transistor’s nonlinearity to cancel that of the main device It utilizes MOS transistors working in a triode or weak inversion region. A conventional post-distortion technology method will degrade IIP3 performance due to the contribution of the second-order nonlinearity of MAUX [14]. The proposed post-distortion network is composed of transistor MAUX operating in a weak inversion region consuming low power. The paper is organized as follows: Section 2 details the design method of the proposed X-band linearized LNA including analysis for the input matching network, power gain, and novel post-distortion technology.
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