Wideband low noise amplifiers employing noise cancelling technique

• Main Author: Yu, Haohong
• Other Authors: Boon Chirn Chye
• Format: Theses and Dissertations
• Language: English
• Published: 2019
• Subjects: Engineering::Electrical and electronic engineering::Wireless communication systems
• Online Access: https://hdl.handle.net/10356/104239; http://hdl.handle.net/10220/50203
• Institution: Nanyang Technological University

Currently, wideband receiver had become a highly popular research topic because of its capability to support both high-speed communication as well as multi-standard integration. Ultra-wideband (UWB) wireless transmission standard was established by Federal Communication Commission (FCC) to support high-speed transmission using bandwidth from 3.1 – 10.6 GHz. Software defined radios (SDRs) have enabled multistandard wideband receiver, which covers multiple wireless standards distributed over sub-6-GHz bands, such as WiFi, GSM and Bluetooth. The first building block in such wideband receivers, wideband low-noise amplifier (LNA), is critical to the performance of the entire receiver chain. Noise cancelling (NC) is an interesting technique in wideband LNA design. It breaks the trade-off between input matching and noise performance of LNA. By adding two feedforward paths using two auxiliary amplifiers, the noise of input transistor is cancelled at output. The objective of this research is to explore this technique and propose novel NC LNA architectures that exploit improvements in gain, noise figure and linearity. These architectures are verified through simulation as well as silicon measurements. A wideband resistive-feedback NC LNA with an additional source-follower-feedback (SFF), which improves both gain and NF, is presented. Fabricated in a 65nm CMOS process, the wideband LNA achieves a flat S21 of 16.8 dB, a flat NF of 2.87-3.77 dB and S11 below -10 dB over a 3-dB bandwidth of 0.5-7 GHz. It consumes a DC power of 11.3mW from a 1.2-V supply and occupies an active area of only 0.044mm2. Nevertheless, this LNA shows a mediocre IIP3 of -4.5 dBm, rendering the circuit vulnerable to intermodulation interference. To address linearity issue in wideband application, a common-gate noise canceling LNA employing pMOS-nMOS complimentary pair as distortion cancellation is proposed. It is crucial for wideband LNAs to achieve high IIP3, preventing in-band intermodulation interference. Fabricated in a 65nm CMOS process, the wideband LNA achieves an S21 of 12.8 dB, a flat NF of 3.3-5.3 dB and S11 below -10 dB over a 3-dB bandwidth of 1-20 GHz. It shows an IIP3 larger than 2 dBm across the entire 19 GHz bandwidth and the highest measured IIP3 is 6.8 dBm