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    A Wideband Low-Power-Consumption2232.5-GHz 0.18-m BiCMOS Active

    Balun-LNA With IM2 CancellationUsing a Transformer-CoupledCascode-Cascade Topology

    Chadi Geha, Student Member, IEEE, Cam Nguyen, Fellow, IEEE, and Jose Silva-Martinez, Fellow, IEEE

    Abstract A low-power-consumption wideband 0.18-mBiCMOS active balun-low noise amplifier (LNA) with linearityimprovement technique for millimeter-wave applicationsis proposed. The linearity technique utilizes constantGm transconductance structure with the second-orderintermodulation (IM2) cancellation that provides robustness toinput and output variations. The constant Gm is establishedwith equal emitters area ratios and proper base-emitter biasingvoltage, thus improving linearity. Furthermore, power savingis achieved using inductive coupling boosting the overall Gmstructure and reducing the current consumption for the auxiliarygain stage. The measured balun-LNAs power gain between theinput and two outputs is 15.4 and 15.6 dB with input returnloss greater than 8.7 dB. The gain and phase mismatches areless than 1.8 dB and 12, respectively. The balun-LNA noisefigures between the input and two outputs are less than 5.5and 6 dB at 32.5 GHz. The measured input points [referred1-dB gain compressions (Pin1dBs), input referred third-orderintercept IIP3s] and the input referred second-order interceptpoints (IIP2s) are more than 14.6, 5.7, and 42 dBm across2232.5 GHz, respectively, and the total power consumption isless than 9 mW drawn from 1.8 V power supply.

    Index Terms Active balun, balun-LNA, BiCMOS, CMOS, lownoise amplifier (LNA), radio-frequency integrated circuit (RFIC).


    RECENT Federal Communications Commission regula-tions have freed up some unlicensed millimeter-wave(mm-wave) frequencies [1], [2]. Such regulations stem fromlower overcrowded spectrums and the increasing demandof users for high data rate wireless communications andradar sensors. Receivers targeting microwave and mm-waveapplications based on the wireless metropolitan area networkstandards ranging from 10 to 66 GHz, ultrawideband radar

    Manuscript received January 23, 2016; revised July 4, 2016 andSeptember 24, 2016; accepted October 2, 2016. Date of publicationDecember 2, 2016; date of current version February 8, 2017. This paperwas made possible by NPRP Grant # 6-241-2-102 from the Qatar NationalResearch Fund (a member of Qatar Foundation). The statements made hereinare solely the responsibility of the authors.

    The authors are with the Department of Electrical and Computer Engi-neering, Texas A&M University, College Station, TX 77843 USA (e-mail:geha_chadi@tamu.edu; cam@ece.tamu.edu).

    Color versions of one or more of the figures in this paper are availableonline at http://ieeexplore.ieee.org.

    Digital Object Identifier 10.1109/TMTT.2016.2623778

    vehicular sensor from 22 to 29 GHz, military radar forunmanned aerial vehicles from 35 to 37 GHz [3], and soon are essential to achieve the user end demands. This fre-quency spectrum allocation still encounters adjacent channelcoexistence, similar to lower frequency spectrums, like radioastronomy at 23.624 GHz, industrial-scientific-medical at24.0524.25 GHz, local multipoint-distribution system at31 GHz, and cloud radar at 35 GHz [4]. In fact, it presentsa dilemma for some sensitive frequency bands where over-lapping exists. The design of silicon-based radio-frequencyintegrated circuit (RFIC) receiver front ends at these frequen-cies for wideband performance with simultaneously high gainand high linearity is very challenging. The low-noise amplifier(LNA) plays a crucial role in achieving high gain and linearityover wide operating frequency ranges for these receivers.Active balun-LNAs are capable of providing differential out-puts from a single-ended input and are important componentin receivers. Various wideband active balun-LNAs on sili-con at low frequencies, which implement active and passivefeedback mechanisms to improve linearity, gain, and phasemismatches, have been reported [5], [6]. However, employingactive feedback comes at the expense of power and nonlin-earity rendering the harmonics cancellation ineffective [6].A linearization technique based on derivative superpositionand its improved derivative version tend to provide impres-sive input referred third-order intercept point (IIP3) [7], [8].The derivative superposition methods use auxiliary n/pMOSpath in weak inversion to cancel the third-order nonlinearcurrent of the main transconductance gain-stage path, thusenhancing IIP3. Nonetheless, this improvement is subjectto deter the second intermodulation product (IP2) due tononlinear cross terms between the two paths [7]. Further-more, current-mode balun-LNA-based common-gate common-source structures with bias control and output conductancekept constant show optimum behavior for both noise andlinearity [9], [10]. Such a constraint across wideband iscostly in terms of power consumption and subject to process,voltage, and temperature variations. Anotherapproach is mak-ing the third intermodulation (IM3) cancellation independentof frequency in bipolar junction transistor (BJT) [11][13].A second-harmonic control with fully differential mode

    0018-9480 2016 IEEE. Personal use is permitted, but republication/redistribution requires IEEE permission.See http://www.ieee.org/publications_standards/publications/rights/index.html for more information.


    configuration using BJT devices facilitates frequency-independent IM3 cancellation [11]. In [12] and [13], IM3 can-cellation happens due to current hyperbolic tangent behaviorfrom dual gated BJT devices in differential and pseudodif-ferential modes added to the output. However, the cost isdoubled in noise and power consumption. All of these tech-niques were implemented in designs operating below 2.4 GHz.A 20-GHz balun-LNA using 0.25-m SiGe BiCMOS tech-nology was reported in [14]. This balun-LNA consists ofa common-emitter (CE) gain stage followed by a single-to-differential output buffer stage using a CE common-base(CE-CB) structure with ac current source. This designsuffers from very high phase and gain mismatches,thus limiting the bandwidth. In [17], a dc-50-GHzbalun-LNA based on distributed (CB-CE) structure usingtransmission line for phase correction in 90-nm CMOS wasdeveloped. In addition, a dc-50-GHz balun using (CE-CC)design approach was shown in [18] using 0.18-m SiGeBiCMOS technology. A single transistor with feedback net-works utilized as balun based on signal-splitter topology (CE-CC) operates from dc-70 GHz using 0.35-m SiGe BiCMOStechnology [19]. Furthermore, [23] exhibited a balun-LNAstructure with two parallel balanced differential amplifiersoperating from 60 to 67 GHz using 90-nm CMOS designprocess. Finally, a dc-60-GHz balun-LNA with distributedcommon-gate common-source structure using 65-nm CMOStechnology was reported in [24]. These works show a tradeoffbetween linearity, power consumption, and gain.

    In this paper, a 0.18-m SiGe BiCMOS 2232.5-GHz activebalun-LNA with high linearity and low power consumptionis presented. The linearity improvement is attained using anew linearity technique based on a constant Gm-cell transcon-ductance that forms the balun-LNA structure. The constantGm-cell transconductance is established through equal emit-ters area ratios of the balun-LNA. The constant small-signalGm-cell transconductance remains independent of input andoutput variations under large-signal behavior and provides thesecond-order intermodulation (IM2) cancellation, resulting inimproved linearity. The low power consumption is due inpart to the coupled inductors used between cascaded stages.The balun-LNA targets multistandard multichannel receiversapplications ranging from 22 to 32.5 GHz that require highlinearity. Many microwave and mm-wave applications not onlycoexist, but also overlap each other on the same frequencyspectrum, making the linearity the bottle neck for the receiversdynamic range.

    This paper is organized as follows. Section II dis-cusses the proposed balun-LNA architecture. Section IIIdescribes the design and implementation of coupled induc-tors model. Section IV provides the simulation and experi-mental results, and the conclusion remarks are presented inSection V.


    Fig. 1 shows the schematic of the 2232.5-GHz (single-to-differential) wideband active balun-LNA with high-gain, high-linearity, and low power consumption. Table I shows all the

    Fig. 1. Schematic of the proposed balun-LNA.



    design parameters of the component in Fig. 1. The proposedbalun-LNA architecture consists of a main transconductancegm gain stage, Q1, coupled to an auxiliary gain path, Q2,through a transformer. The coupled transformer increases thesignal swing at the input of the second stage, thus boostingthe Gm transconductance, hence gain, and reducing the powerconsumption. The composite Gm cell defined by transistors I1,Q2, and Q3 plays a major role in improving the linearizationof the structure. The stipulated total Gm stays constant evenin the presence of variations in gm1 of Q1 and gm2 of Q2 dueto high input power. As the collector currents of transistorsQ1and Q2 vary from their quiescent bias under large voltageswing, the gms dependency on equal emitters area (Ae) ratioskeeps the overall Gm-cell constant. The overall Gms constantand frequency-independent characteristic behavior with IM2cancellation results in linearity enhancement. A simple wide-band input matching network is established using inductors Lband Le1 similar to [15]. The effect of the coupling transformers(Le1 and Lb2) on t