LO Signal Research Articles

A 24–30‐GHz Modified Gilbert‐Cell Downconverter With High Linearity and Isolation

ABSTRACTThis paper introduces a downconverter mixer employing a modified double‐balanced Gilbert‐cell topology, designed using IHP's 0.13‐m SiGe BiCMOS technology. Distinct from the conventional topology, a resonator was employed at the emitter of the transconductance stage, which enables the utilization of transconductance stage as an active balun, allowing for direct feeding of the single‐ended input without sacrificing the advantageous of the double‐balanced topology. The integration of the resonator reduces the amplitude and phase errors within the active balun segment, thereby enhancing port‐to‐port isolation. The area occupied by the resonator is approximately 1.7 times smaller than that of an RF transformer balun typically employed in conventional double‐balanced topologies. The LO and IF differential signals are converted to single‐ended ones through transformer baluns for measurement purposes. The frequencies of operation for RF, LO, and IF are 24–30, 18–24, and 6 GHz, respectively. The conversion loss is 7.7 dB at 26 GHz, with port‐to‐port isolations exceeding 35 dB. The input 1‐dB compression point is 5.7 dBm, while the circuit consumes 65‐mW power from a 3.3‐V voltage supply. Excluding the pads, the active area of the design spans 1 mm2.

A Q-Band CMOS Image-Rejection Receiver Integrated with LO and Frequency Dividers

This paper presents a Q-band image-rejection receiver using a 65 nm CMOS technology. For a high image-rejection ratio (IMRR), the Q-band receiver employs the Hartley architecture which consists of a Q-band low-noise amplifier, two down-conversion mixers, a 90° hybrid coupler, and two IF baluns. In addition, a Q-band fundamental voltage-controlled oscillator (VCO) and a frequency divider chain divided by 256 are integrated into the receiver for LO. A charge injection technique is employed in the mixers to reduce the DC power while maintaining a high conversion gain and linearity. The VCO adopts a cross-coupled topology to secure stable oscillation with high output power in the Q-band. The frequency divider chain is composed of an injection-locked frequency divider (ILFD) and a multi-stage current-mode logic (CML) divider to achieve a high division ratio of 256, which facilitates the LO signal locking to an external phase-locked loop. An inductive peaking is employed in the ILFD to widen the locking range. The Q-band image-rejection receiver exhibits a peak conversion gain of 16.4 dB at 43 GHz. The IMRR is no less than 35.6 dBc at the IF frequencies from 1.5 to 5 GHz.

Photonic-Assisted Reconfigurable LO Harmonic Downconverter With RF Self-Interference Cancellation and Image-Rejection

A photonic-assisted reconfigurable LO harmonic downconverter with simultaneous image-rejection and RF self-interference cancellation (SIC) for in-band full-duplex communication is proposed and experimentally investigated based on a dual-polarization dual-parallel Mach–Zehnder modulator (DP-DPMZM). The received signal from the antenna, which includes the radio frequency (RF) signal, image signal (IM) and self-interference (SI) signal, is input into one sub-MZM of the X-DPMZM. The self-reference (SR) signal is input into the other. The Y-DPMZM is used to load the LO signal and is properly biased to obtain the high-order sideband of the LO signal, which was then set as the LO signal of the reconfigurable harmonic frequency downconverter. By matching the power and delay of the SR signal and changing the main bias of the X-DPMZM, the SI signal can be eliminated directly in optical domain. With power splitting after the output of the DP-DPMZM, the quadrature IF signals can be obtained by a photonics-based continuously adjustable phase shifter. Then, photonics image-rejection down-conversion based on phase cancellation is realized after a low-frequency electrical 90° hybrid coupler (HC) combines the quadrature IF signals. Both theoretical and experimental investigations are performed. The results show that the SIC has a cancellation depth more than 32 dB for the 10-MHz bandwidth and greater than 19 dB for the 500-MHz bandwidth, the image-rejection has an image-rejection ratio larger than 31 dB for 10-MHz bandwidth and larger than 22 dB for the 100-MHz bandwidth, both in 2 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">nd</sup> - and 3 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">rd</sup> -order harmonic down-conversion mode. Experiments are also carried out on the reconfigurable LO harmonic downconverter with simultaneous SIC and image-rejection. A 16-quadrature amplitude modulation (16-QAM) -modulated RF signal is successfully down-converted to a 1-GHz intermediate frequency (IF) signal with self-interference and image frequency cancelled. It is verified that the RF signal can be well recovered from SI and IM signals by the proposed system.

A D-Band Direct-Conversion IQ Receiver with 28 dB CG and 7.3 dB NF in 130 nm SiGe Process.

In this paper, a D-band direct conversion IQ receiver with on-chip multiplier chain is presented. The D-band LNA with gain-boosting and stagger-tunning technique is implemented to provide high gain and large bandwidth. X9 multiplier chain including Marchand balun and quadrature (90°) hybrid is employed to provide four path LO signal to drive IQ mixer. This receiver is implemented in a 130nm SiGe process and consumes a core area of 1.04 mm2. From the experimental results, the proposed receiver exhibits a 20 GHz bandwidth from 150 GHz to 170 GHz, with CG of 28 dB and NF of 7.3 dB at 158 GHz.

NLO QCD and EW corrections to off-shell tZj production at the LHC

The production of a single top quark in association with a Z boson (tZj production) at the LHC is a relevant probe of the electroweak sector of the Standard Model as well as a window to possible new-physics effects. The growing experimental interest in performing differential measurements for this process demands an improved theoretical modelling in realistic fiducial regions. In this article we present an NLO-accurate tZj calculation that includes complete off-shell effects and spin correlations, combining QCD and electroweak radiative corrections to the LO signal. Integrated and differential cross sections are shown for a fiducial setup characterised by three charged leptons, two jets, and missing energy.

Dual-Output Microwave Photonic Frequency Up- and Down-Converter Using a 90° Optical Hybrid Without Filtering

A dual-output microwave photonic frequency up- and down-converter using a 90° optical hybrid without filtering is proposed. By using a dual-parallel Mach-Zehnder modulator and a Mach-Zehnder modulator in parallel to realize carrier suppressed single sideband and carrier suppressed double sideband modulation, respectively, with a 90° optical hybrid and 90° electrical hybrid coupler, this scheme can implement two functions: simultaneous up- and down-conversion signal generation, or high image rejection in down-conversion. Simulation results show that the proposed structure can achieve an up-conversion with a tunable range of 17–23 GHz or a down-conversion with a tunable range of 1–7 GHz, respectively, based on a fixed 8 GHz LO signal. The unwanted signal suppression ratio of desired signal is about 27.2 dB for up-conversion and 30.0 dB for down-conversion. In addition, we have tested and analyzed the conversion gain, noise figure and spurs free dynamic range of the system. For image rejection in down-conversion, we can achieve an image rejection ratio (IRR) about 65.2 dB. Moreover, the impact of the phase drift, RF frequency, amplitude and phase variation on IRR is discussed. Finally, the influence of half-voltage imbalance of the DPMZM sub-modulators on IRR is analyzed, and a compensation method is given.

High Conversion Gain Self-Oscillating Mixer for 5G mm-wave Applications

We develop in this paper, a high conversion gain self-oscillating mixer (SOM) for 5G mm-wave applications using commercial 0.15µm GaAs PHEMT from UMS foundry. The up-conversion SOM transpose the IF signal from 2 GHz to 26 GHz LSB (lower sideband) signal using a 28GHz LO signal. The simulation results show that the SOM has a maximum conversion gain of 19dB, according to our knowledge, this structure presents the highest gain compared to SOMs published in the literature. While the 1dB compression point is obtained for an IF power of -20.6 dBm. The SOM circuit consumes 129mW and it occupies an area of 0.741 mm2.

Heterodyne terahertz detection based on antenna-coupled AlGaN/GaN high-electron-mobility transistor

In this article, we report an antenna-coupled AlGaN/GaN high-electron-mobility transistor integrated on a hyper-hemispheric silicon lens for heterodyne detection in a 340 GHz band at room temperature. The responsivity, elevated shot noise, flicker noise, and dynamic source-drain resistance for homodyne and heterodyne detection are characterized and analyzed at different local terahertz (LO) power levels. With a LO power of only −3.9 dBm, the detector offers a conversion loss less than 28 dB and a noise-equivalent power (NEP) about −132 dBm/Hz. A threshold LO power about −5 dBm is identified above which the shot noise becomes the dominant noise source, and the intermediate-frequency response is strongly suppressed. The elevated noise and the saturation in responsivity are found to be closely related to the strong direct-current homodyne current and the charge modulation/accumulation by the LO signal. Possible solutions are discussed to further reduce the NEP and the conversion loss.

Dual-Band Direct Conversion Receiver With Additive Mixing Architecture

A dual-band direct conversion receiver based on additive mixing architecture for low-cost and multi-mode wireless communication systems is proposed. The proposed receiver consists of two active four-port junctions for additive mixing and one-stage dual-band polyphase filter for quadrature LO signal generation. Each four-port junction is fabricated with <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.18~\mu \text{m}$ </tex-math></inline-formula> CMOS technology and configured by an active balun, two buffer amplifiers, two active combiners and two power detectors. The proposed polyphase filter is implemented using type-I architecture adopting one-stage and R-LC resonance type for low power and dual-band operation. The phase and amplitude calibration schemes are also integrated to effectively correct I/Q mismatch within the proposed architecture. The calibration ranges for the phase and amplitude mismatches show 8° and 14 dB, respectively. The validity of the proposed receiver based on additive mixing method is successfully demonstrated by demodulating 16-QAM signals with 40 Mbps at the dual band of 900 MHz and 2.4 GHz.

Under-Sampling Digital Predistortion of Power Amplifier Using Multi-Tone Mixing Feedback Technique

An under-sampling digital predistortion based on a multi-tone mixing feedback technique (MTM-DPD) is presented in this article. In contrast to the under-sampling digital predistortion (DPD) based on conventional receivers, the proposed method could simultaneously reduce the sampling rate and acquisition bandwidth using a multi-tone mixing (MTM)-based feedback channel. The MTM-DPD is implemented with an evolved direct learning architecture, where the coefficients of a predistorter are estimated based on the aliased feedback signal, preprocessed input signal, and preprocessed kernels of the DPD model. To preprocess the input signal and kernels, the behavioral model of the MTM-based feedback channel and its corresponding identification algorithm are analyzed in detailed. Experimental results show that for a gallium nitride (GaN)-based power amplifier (PA) with 40-MHz input, under the excitation of a 17 tone LO signal with frequency interval 7.68 MHz, the MTM-DPD with sampling rate 15.36 MSPS and acquisition bandwidth 15.36 MHz could improve the adjacent channel power ratio (ACPR) from −30.1 to −46.5 dBc and the error vector magnitude (EVM) from 9.13% to 1.76%. Compared with the conventional full sampling DPD (FS-DPD), the MTM-DPD could reduce the cost of analog-to-digital converters (ADCs) in feedback channel significantly while maintaining satisfactory linearization performance.

Design of a Novel 2.4GHz RF Transmitter

The world of Wireless Technology has been improving consistently due to its high speed and reliability. Some of the demands that need to be fulfilled include larger network capacity, improved data rates and so on. This paper focuses on the design and simulation of the Transmitter, which is a key component in an RF Transceiver Module. It is built by cascading an Up Conversion Mixer, a Bandpass Filter and a Power Amplifier as its most fundamental units. The Cadence Virtuoso Tool was used to construct this Transmitter block in 180nm node technology. The IF signal to the Mixer is 100 MHz and the LO signal is 2.3GHz. The 2.4GHz amplified RF output is taken from the Power Amplifier. A 1dB compression point of -25.91 dBm and an IIP3 of 10.14 dBm is observed for the proposed design. Future work involves testing its integrity with an RF Receiver module that has appropriate modulation schemes in place and converting it into a physical layout-based IC.

Design of a Novel 2.4GHz RF Transmitter

The world of Wireless Technology has been improving consistently due to its high speed and reliability. Some of the demands that need to be fulfilled include larger network capacity, improved data rates and so on. This paper focuses on the design and simulation of the Transmitter, which is a key component in an RF Transceiver Module. It is built by cascading an Up Conversion Mixer, a Bandpass Filter and a Power Amplifier as its most fundamental units. The Cadence Virtuoso Tool was used to construct this Transmitter block in 180nm node technology. The IF signal to the Mixer is 100 MHz and the LO signal is 2.3GHz. The 2.4GHz amplified RF output is taken from the Power Amplifier. A 1dB compression point of -25.91 dBm and an IIP3 of 10.14 dBm is observed for the proposed design. Future work involves testing its integrity with an RF Receiver module that has appropriate modulation schemes in place and converting it into a physical layout-based IC.

A 77-GHz High Gain Low Noise Receiver for Automatic Radar Applications

In this paper, a high gain 77-GHz receiver with a low noise figure (NF) was designed and implemented in a 40-nm CMOS process. With the purpose of making better use of active devices, an extra inductor, Ld, is adopted in the new neutralization technique. The three-stage differential low noise amplifier (LNA) using the proposed technique improves the voltage gain and reduces the NF. The receiver design utilizes an active double-balanced Gilbert mixer with a transformer coupling network between the transconductance stage and the switch stage. The flicker noise contribution from the switch MOS transistors is largely reduced due to the low DC current of the switch pairs. The LO signal is provided by an on-chip fundamental voltage-controlled oscillator (VCO) with a tuning range from 70.5 to 78.1 GHz. A conversion gain of 32 dB and a NF of 11.86 dB are achieved at 77 GHz by the designed receiver. The LNA as well as the mixer consume a total DC power of 33.2 mW and occupy a core size of 1 × 0.38 mm2.

Subharmonic single-balanced LMV with bottom LO injection

This paper proposes a subharmonic single-balanced RF receiver front-end (called LMV) where low noise amplifier is stacked on top of a differential voltage-controlled oscillator (VCO) to re-use the dc bias current. In this subharmonic (SH) LMV, the VCO itself plays the role of the single-balanced subharmonic mixer while generating an LO signal. This bottom LO SH LMV has good LO to IF and LO to RF leakage performances. Also, it can reduce the die size on a chip since it requires only one inductor for the VCO instead of two in the case of top LO LMV.Oscillating at around 2.4 GHz band, the proposed SH LMV is designed using a 65 nm CMOS technology and compared to the top LO SH LMV in terms of phase noise, conversion gain and double sideband noise figure. The SH LMVs consume about 160 μW dc power from a 1-V supply.

Filter-Free Photonic Image-Rejection Down-Conversion for Distributed Antenna Applications

Photonics-assisted frequency conversion based on cascaded modulators is an effective way to satisfy the requirements of distributed antenna array applications. A filter-free photonic image-rejection down-converter with immunity to dispersion-induced power fading is proposed and demonstrated. The radio frequency (RF) signal from the distributed antenna unit is injected into a dual-drive Mach–Zehnder modulator (DDMZM) through an electrical 90° hybrid coupler (HC), and a single-sideband (SSB) signal is realized. It is then transmitted to the center office by an optical fiber link. At the center office, the modulated RF signal is injected into a dual-polarization dual-parallel MZM (DP-DPMZM) after a polarization controller (PC). Afterwards, an LO signal remodulates it through the Y-DPMZM, and carrier-suppressed SSB modulation is fulfilled via another electrical 90° HC. After the power splitting, quadrature I and Q IF signals can be obtained by a photonics-based continuously adjustable phase shifter. Through a combination of the I/Q IF signals with a low-frequency electrical 90° HC, a photonics image-rejection down-converter based on phase cancellation is realized. Moreover, no optical filter is required; thus, the image-rejection down-converter can work with a large bandwidth. The proposed filter-free photonic image-rejection down-converter is theoretically analyzed and experimentally verified.

Compartmentalization of phosphatidylinositol 4,5-bisphosphate metabolism into plasma membrane liquid-ordered/raft domains

Possible segregation of plasma membrane (PM) phosphoinositide metabolism in membrane lipid domains is not fully understood. We exploited two differently lipidated peptide sequences, L10 and S15, to mark liquid-ordered, cholesterol-rich (Lo) and liquid-disordered, cholesterol-poor (Ld) domains of the PM, often called raft and nonraft domains, respectively. Imaging of the fluorescent labels verified that L10 segregated into cholesterol-rich Lo phases of cooled giant plasma-membrane vesicles (GPMVs), whereas S15 and the dye FAST DiI cosegregated into cholesterol-poor Ld phases. The fluorescent protein markers were used as Förster resonance energy transfer (FRET) pairs in intact cells. An increase of homologous FRET between L10 probes showed that depleting membrane cholesterol shrank Lo domains and enlarged Ld domains, whereas a decrease of L10 FRET showed that adding more cholesterol enlarged Lo and shrank Ld Heterologous FRET signals between the lipid domain probes and phosphoinositide marker proteins suggested that phosphatidylinositol 4,5-bisphosphate [PtdIns(4,5)P2] and phosphatidylinositol 4-phosphate (PtdIns4P) are present in both Lo and Ld domains. In kinetic analysis, muscarinic-receptor-activated phospholipase C (PLC) depleted PtdIns(4,5)P2 and PtdIns4P more rapidly and produced diacylglycerol (DAG) more rapidly in Lo than in Ld Further, PtdIns(4,5)P2 was restored more rapidly in Lo than in Ld Thus destruction and restoration of PtdIns(4,5)P2 are faster in Lo than in Ld This suggests that Lo is enriched with both the receptor G protein/PLC pathway and the PtdIns/PI4-kinase/PtdIns4P pathway. The significant kinetic differences of lipid depletion and restoration also mean that exchange of lipids between these domains is much slower than free diffusion predicts.

Linearized Photonic Microwave and mm-Wave Mixer With Dispersion-Induced Power Fading Compensation

A novel photonic microwave and millimeter-wave (mm-wave) mixer with simultaneous third-order intermodulation distortion (IMD3) suppression and dispersion-induced power fading compensation is proposed and experimentally demonstrated. In our proposed scheme, a dual-polarization quadrature phase shift-keying (DP-QPSK) modulator is used to modulate RF/IF and LO signals. The bias voltages of the main modulators are adjusted to compensate dispersion-induced power fading. When the polarization state of the modulated signal and the attenuation of the RF signal are properly adjusted, IMD3 distortion can be suppressed. In the experiment, relatively flat microwave and mm-wave signals from 11 to 35 GHz are obtained through 4and 50-km fiber transmission, while the measured spurious free dynamic range (SFDR) is 112.9 dB·Hz4/5. In addition, an upconverted 16 quadrature amplitude modulation (16 QAM) vector signal with a carrier frequency of 19.3 GHz is obtained and the measured constellation diagrams and error vector magnitudes are given after transmission over different fiber lengths (back to back, 4 and 50 km).

A filterless reconfigurable frequency mixer based on a wideband photonic microwave phase shifter

In this paper, a filterless reconfigurable frequency mixer based on a wideband photonic microwave phase shifter is proposed. The main device is a single PDM-DPMZM which is applied to generate a pair of orthogonally polarized CS-SSB signals. A pair of PCs are followed to introduce a tunable phase to the CS-SSB signals. By changing the detection scheme of the output optical signals and tuning the PCs, single-ended, double-balanced, I/Q, and image-reject mixer can all be achieved with the capability of full range phase shifting. And it can also perform frequency up- and down-conversion switching by adjusting the DC biases of the modulator. A simulation is carried out to demonstrate its versatility, flexibility and reconfigurability. The measured image-rejection ratio of the image rejection mixer is about 65 dB. In addition, the frequency operation range, practical applicability and feasibility are discussed. The effect of non-ideal factors or adjustable parameters, i.e., extinction ratio deterioration, DC biases drift, phase inaccuracy between I/Q path, instability or inaccuracy of the PC and LO signal power variation on system performance are also analyzed.

A 0.2–3.3 GHz 2.4 dB NF 45 dB gain CMOS current-mode receiver front-end

A CMOS fully differential current-mode front-end for SAW-less receivers is proposed. The noise-canceling LNTA has a main path of the common-gate (CG) stage and an auxiliary path of the inverter stage. A current mirror is used to combine the signals from the main and auxiliary paths in current mode. The stacked nMOS/pMOS configurations improve their power efficiency. The traditional stacked tri-state inverter as D-latch replaced by the discrete inverter and transmission gate enables a reduced supply voltage of divider core. LO generator based on the improved divider provides quarter LO signals to drive the proposed LNTA-shared receiver front-end. Simulation results in 180 nm CMOS indicate that the integrated receiver front-end provides an NF of 2.4 dB, and a maximum gain of 45 dB from 0.2 to 3.3 GHz. The in-band (IB) and out-of-band (OB) IIP3 of 2.5 dBm and 4 dBm, are obtained, respectively. With CMOS scaling down continuously, CMOS devices are providing increased transit frequency and reduced intrinsic parasitics which are important for radio frequency (RF) and millimeter-wave applications. As a promising solution, CMOS RF delivers comparable performance to silicon bipolar and GaAs devices but at a much lower cost and higher integration level. Supply voltage reduction with CMOS scaling down also poses a stringent linearity requirement. Avoiding the conventional trade-off between the supply voltage and linearity headroom, the proposed receiver front-end based on the current mode principle is with weak linearity dependency on the supply voltage and provides excellent anti-blocker interference capability.

A 28-GHz 16-Gb/s High Efficiency 16-QAM Transmitter in 65-nm CMOS

This work presents the design and implementation of an ultra-broadband quadrature common-mode amplitude modulator (QCAM) to generate high power back-off efficiency 16-QAM signals. The proposed QCAM transmitter consists of I- and Q-path PAM4 modulators, which digitally modulate the power amplifier (PA) output stage to relax the linearity requirement. An interleaved differential transformer-based coupler is proposed for wide-band combination of the baseband and LO signals. The I and Q PAM4 signals are combined using an on-chip Wilkinson power combiner to generate the 16-QAM output signal. The 28-GHz 16-QAM transmitter test chip, implemented in 65-nm CMOS, achieved measurement results of 11.35 dBm average RF output power, 9.2% DC-RF efficiency, 16 Gb/s data rate, and −24 dB EVM.