Generally a communication system is made-up of “transmitter, channel and receiver.” The architecture of narrowband receivers has had many changes since the beginning of the 19th century, but in recent years (2002~2019), design of multistandard receivers has become very important for designers because users prefer to receive all RF signals (such as Radio, TV, etc.) by one device. Commercial multistandard devices (e.g. Cellphones) are composed of many Surface-Acoustic-Wave (SAW) filters and receiver-circuits in one RFIC package for picking-up and demodulating signals, but recent studies have been focused on wideband Low Noise Amplifier (WB LNA) that these efforts will lead to have a SAW-less multistandard receiver with one WB LNA. Papers’ of Rui Ma et al [1], Jian Tao et al [2] and Amirhossein Rasekh et al [3] are some researches which are published in IEEE in 2019 that it clearly indicates the novelty of this issue.

My design proposes a circuit to detect and pick-up our desirable RF-signals from different standards without using a SAW filter. It is able to cancel all nonlinearity effects of LNA, detect all signals even with 1μV amplitude which their frequencies are between 80MHz to 10GHz, and also prove that there is a condition that NF and IIP are no longer demonstrative figure-of-merits. This research is done by MATLAB, ADS and PSpice software and it includes the comparison between calculated results and simulated ones. Its characteristics are: A_V=18~22dB, Z_in=50Ω, NF_LNA=1.3~3dB, P_DC(LNA)=140~156μW, P_DC(Limiter)=918~972μW. Moreover, this LNA doesn’t need AGC Unit because its output never saturates our RFIC. This study presents a novel idea with a simplest structure.

In fact, it proposes a technique to cancel all effects of Blockers and Interferers in a nonlinear LNA without changing IIP_2 and IIP_3 values. It also illustrates that NF and IIP are just figure-of-merits (not physical facts such as current) which are no longer demonstrative under a specific condition. This issue is not only related to NF and IIP, and you can observe it for other figure-of-merits such as PDP [4]. My illustration files (part 1~3) only display and explain calculation and simulation results to prove the validity of my design (results are close to each other), but the circuit schematic and details will be just submitted to customer after contract.

References:

[1] Rui Ma, Martin Kreißig, Frank Ellinger, “A Fast Switchable and Band-Tunable 5–7.5 GHz LNA in 45 nm CMOS SOI Technology for Multi-Standard Wake-up Radios,” 25th IEEE International Conference on Electronics, Circuits and Systems (ICECS), January 2019.

[2] Jian Tao, Xiangning Fan, Xin Chen, Yuan Zhao, “A Differential balun-LNA for Multistandard Receivers in 0.13 μm BiCMOS,” IEEE International Conference on Automation, Electronics and Electrical Engineering (AUTEEE), May 2019.

[3] Amirhossein Rasekh, Mehrdad Sharif Bakhtiar, “Wide-Band RF Front End for SAW-Less Receivers Employing Active Feedback and Far Out-of-Band Blocker Rejection Circuit,” IEEE Journal of Solid-State Circuits, Volume: 54, Issue: 6, June 2019.

[4] Salimeh Shahrabadi, “Investigating PDP-based error by testing NAND and D-Latch based on CNTFET (Stanford model),” SN Applied Sciences, 1:702, July 2019.