IF Bandwidth Research Articles

A Low-Power Fully Monolithic Subthreshold CMOS Receiver With Integrated LO Generation for 2.4 GHz Wireless PAN Applications

This paper reports a fully monolithic subthreshold CMOS receiver with integrated subthreshold quadrature LO chain for 2.4 GHz WPAN applications. Subthreshold operation, passive voltage boosting, and various low-power circuit techniques such as current reuse, stacking, and differential cross coupling have been combined to lower the total power consumption. The subthreshold receiver, consisting of the switched-gain low noise amplifier, the quadrature mixers, and the variable gain amplifiers, consumes only 1.4 mW of power and has a gain of 43 dB and a noise figure of 5 dB. The entire quadrature LO chain, including a stacked quadrature VCO and differential cross-coupled buffers, also operates in the subthreshold region and consumes a total power of 1.2 mW. The subthreshold receiver with integrated LO generation is implemented in a 0.18 mum CMOS process. The receiver has a 3-dB IF bandwidth of 95 MHz.

A 26–38 GHz Monolithic Doubly Balanced Mixer

A novel configuration of doubly balanced mixer is presented for operating over the 26-38 GHz band. The monolithic microwave integrated circuit (MMIC) was implemented by GaAs 0.15 mum pHEMT technology with the compact size of 1times2.5 mm2. A 180deg hybrid circuit and two identical Marchand baluns were employed to achieve good port-to-port isolation. They also have wide band performance, make the mixer more compact, and simplify IF extraction. This mixer has a conversion loss of better than 6 dB, a dc-10 GHz IF bandwidth, and the LO-to-RF and LO-to-IF isolations are better than 20 dB and 29 dB, respectively.

An High Performance Ka-band MMIC Fourth Harmonic Image Rejection Diode Mixer

An high performance Ka-band MMIC fourth harmonic image rejection diode mixer is designed using commercial United Monolithic Semiconductors (UMS) process in this paper. Details of design approach and outcome of simulations are presented. The results show that this mixer has a conversion loss less than 15.2 dB and image rejection ratio (IRR) more than 20 dB in the 34–38 GHz with a wide band IF range up to 3 GHz, for a local oscillating (LO) drive power level of 13 dBm.

$K$-Band LTCC Star Mixer With Broadband IF Output Network

This paper presents a hybrid star mixer in a surface-mount package using low-temperature co-fired ceramic technology. The frequency of operation ranges up to 32 GHz for the RF frequency with an achieved conversion loss of as low as 5 dB. The device is optimized for local oscillator (LO) drive levels of down to 7.5 dBm. Various IF output networks with an inherently low series inductance are discussed, offering large IF bandwidths of up to 11.5 GHz with a significant improvement compared to known solutions. Optimization procedures are revealed to achieve higher port isolation and a flat conversion loss function even at low drive levels. Measurements and simulation confirm the design methodologies and approaches.

A 1.5-V 0.7–2.5-GHz CMOS Quadrature Demodulator for Multiband Direct-Conversion Receivers

An integrated quadrature demodulator with an on-chip frequency divider is reported. The mixer consists of a transconductance stage, a passive current switching stage, and an operational amplifier output stage. A complementary input architecture has been used to increase the transconductance for a given bias current. The circuit is inductorless and is capable of operating over a broad frequency range. The chip was implemented in a 0.13-mum CMOS technology. From 700 MHz to 2.5 GHz, the demodulator achieves 35 dB of conversion voltage gain with 250-kHz IF bandwidth, a double-sideband NF of 10 dB with 9-33 kHz 1/f-noise corner. The measured IIP3 is 4 dBm for a 0.1-MHz IF frequency and 10 dBm for a 1-MHz IF frequency. The total chip draws 20 to 24 mA from a single 1.5-V supply.

Gain Enhancement in Inductively-Loaded Distributed SIS Junction Arrays

Due to their very low IF output capacitance, series-connected distributed SIS junction array mixers possess very wide IF bandwidth. However, careful control of parasitic inductance in the IF network is important in order to obtain a flat IF response in this class of wideband mixer. We have studied the effect of inductive loading on the operation of these mixers, both experimentally and theoretically. It is shown that over the range of IF where the reactive part of the load impedance is large, a higher mixer conversion gain accompanied by a lower noise temperature is observed.

Fabrication of a Nb-Based 180-Degree IF Hybrid for Balanced SIS Mixers

180-degree IF hybrids are potentially useful for balanced superconductor-insulator-superconductor (SIS) mixers. We have developed a compact Nb-based 180-degree hybrid for 4-12 GHz which addresses concerns of element size, ohmic loss, and IF bandwidth. The fabrication scheme developed for these elements will be discussed, including the use of a thin overlayer Au process for via contacts, RF diode sputtered SiOx in lieu of sublimated SiOx films in order to improve the wafer yield, and diagnostic Nb capacitors to evaluate these SiOx films. Experimental results will be presented and compared with simulations of these lumped element transmission line rat-race hybrids. It should be noted that the hybrids can be used in cryogenic balanced mixers for any RF band.

Theoretical Simulation of the Mixing Performance of Distributed Superconducting Tunnel Junction Arrays at 1.2 THz

In this paper we focus on the numerical simulation of the mixing behaviors of distributed superconducting junction arrays at 1.2 THz. A novel type of superconducting tunnel junctions, i.e., NbN/AlN/Nb, which have a relatively high gap voltage (4.3 mV) and can reach a critical current density as high as several tens of kA/cm 2 , are proposed for this characterization along with conventional Nb/AlOx/Nb junctions. The former is incorporated with a NbN/SiO 2 /Al tuning circuit, and the latter with a Nb/SiO 2 /Al and a NbTiN/SiO 2 /Al tuning circuits. The noise performance, local-oscillator power requirement, IF bandwidth, and optimum embedding impedance are thoroughly characterized for the two types of distributed superconducting junction arrays.

Characterization of a quasi-optical NbN superconducting HEB mixer

In this paper, the performance of a quasi-optical NbN superconducting hot-electron bolometer (HEB) mixer, cryogenically cooled by a close-cycled 4-K refrigerator, is thoroughly investigated at 300, 500, and 850 GHz. The lowest receiver noise temperatures measured at the respective three frequencies are 1400, 900, and 1350 K, which can go down to 659, 413, and 529 K, respectively, after correcting the loss and associated noise contribution of the quasi-optical system before the measured superconducting HEB mixer. The stability of the quasi-optical superconducting HEB mixer is also investigated here. The Allan variance time measured with a local oscillator pumping at 500 GHz and an IF bandwidth of 110 MHz is 1.5 s at the dc-bias voltage exhibiting the lowest noise temperature and increases to 2.5 s at a dc bias twice that voltage.

60 GHz MMIC double balanced Gilbert mixer in mHEMT technology with integrated RF, LO and IF baluns

A 60 GHz MMIC double balanced Gilbert mixer (DBGM) with integrated RF, LO and IF baluns has been designed, fabricated in an mHEMT MMIC technology and characterised with probed measurements. Although a standard mixer topology for integrated circuits in the low gigahertz region, the DBGM has had very little impact in the millimetre-wave range. To the authors' knowledge, the presented DBGM operates at the highest RF frequency ever published for any FET-based Gilbert type mixer, double or single balanced. A measured down conversion gain of 1.5 dB at 60 GHz is obtained with a DC power consumption of 300 mW. Further, IF bandwidth, isolation between the LO, RF and IF ports, 1 dB compression point for the RF input, and LO input power is presented

A terahertz focal plane array using HEB superconducting mixers and MMIC IF amplifiers

We present a focal plane array (FPA) designed for operation at terahertz frequencies. The FPA is based on NbN phonon-cooled hot electron bolometer mixers directly coupled to wide-band microwave monolithic integrated circuit IF amplifiers. The array incorporates all the required dc-bias and IF circuitry in a compact split-block design. We present new experimental results describing the optical coupling efficiency to the array, as well as receiver noise temperature measurements. The measurements were performed at 1.6 THz, showing good agreement with theoretical predictions. This is the first low-noise heterodyne focal plane array to be reported for any frequency above 1 THz.

A Workable Use of the Floating-Body Silicon-On-Sapphire MOSFET as a Transconductance Mixer

The operation, biasing, and measured performances of the floating-body silicon-on-sapphire (SOS) MOSFET as a single-gate FET upconversion mixer are presented. Despite the floating-body effects of the SOS MOSFET, the upconversion RF mixer operation is feasible by utilizing the approximate square-law transfer characteristics of the SOS MOSFETs. With a drawn gate length Lmin=0.8 µm, the single-gate SOS MOSFET mixer gives an approximately 1.5-dB power conversion gain, an input-referred third-order intercept point (IP3) of 5 dBm while requiring a local oscillator (LO) power of 5.5 dBm with an RF bandwidth of 2 GHz and an IF bandwidth of 400 MHz. The current consumption is about 8 mA with a 3 V voltage supply. The realization of a high output bandwidth and high IF RF mixer is demonstrated to be possible with the floating-body SOS MOSFET.

ミリ波照射時におけるスロットアンテナ結合ＹＢａ２Ｃｕ３Ｏ７‐δマイクロブリッジの応答機構と速度

The study of nonbolometric responses caused by the vortex motion and other factors of YBa2Cu3O7-δ (YBCO) microbridges has received much attention because of possible applications for sensitive and fast response detectors. In this study, we fabricated a slot antenna-coupled YBCO microbridge and investigated IF properties at 94 GHz to evaluate the response speed of the device in the resistive state. The response mechanism of the device biased in the resistive state consists of the bolometric response and the nonbolometric response caused by the flux creep and flux flow. From the measurements of voltage-current (I-V) characteristics and video detection properties, the response mechanism was investigated and operating conditions that dominated the bolometric and nonbolometric responses were obtained. The IF bandwidth of the device, having its response dominated by the bolometric process, showed a constant value of about 60 MHz and did not depend on the bias current. On the other hand, the bandwidth dominated by the flux flow response increased as the bias current and temperature increased, up to 1.2 GHz, and depended on the vortex velocity.

Measurement of intermediate frequency bandwidth of hot electron bolometer mixers at terahertz frequency range

We have developed a new experimental setup for measuring the IF bandwidth of superconducting hot electron bolometer mixers. In our measurement system we use a chopped hot filament as a broadband signal source, and can perform a high-speed IF scan with no loss of accuracy when compared to coherent methods. Using this technique we have measured the 3 dB IF bandwidth of hot electron bolometer mixers, designed for THz frequency operation, and made from 3-4 nm thick NbN film deposited on an MgO buffer layer over crystalline quartz.

Study of the IF bandwidth of NbN HEB mixers based on crystalline quartz substrate with an MgO buffer layer

In this paper, we present the results of IF bandwidth measurements on 3-4 nm thick NbN hot electron bolometer waveguide mixers, which have been fabricated on a 200-nm thick MgO buffer layer deposited on a crystalline quartz substrate. The 3-dB IF bandwidth, measured at an LO frequency of 0.81 THz, is 3.7 GHz at the optimal bias point for low noise receiver operation. We have also made measurements of the IF dynamic impedance, which allow us to evaluate the intrinsic electron temperature relaxation time and self-heating parameters at different bias conditions.

A Fixed-Tuned W-Band Waveguide SIS Mixer with 4.0-7.5 GHz IF

The design and performance of a fixed-tuned W-band SIS mixer with a wide band IF of 4.0-7.5 GHz is presented. Waveguide-to-stripline transition of the SIS mixer is designed using the lumped-gap-source port provided by HFSSTM. Measured receiver noise temperature is less than 25 K in the frequency range of 95-120 GHz, with a minimum value of around 19 K achieved. Mixer noise temperature is determined to be about 8.5 K, which is around twice the quantum limit (i.e., 2hw/k). In spite of the high IF frequencies (f0 = 6 GHz), the performance of the SIS receiver is comparable or even superior to those of the best mechanically-tunable waveguide SIS receivers at low IF frequencies (f0 = 1.5 GHz). This result suggests that it is easy to design waveguide-to-stripline transitions without scale-model measurements.

Analog signal generator for BIST of wideband IF signals bandpass sigma–delta modulator

This paper presents improvements in generation of wideband and high dynamic range analog signal for area-efficient MADBIST, especially for the on-chip testing of wireless communication IF digitizing sigma–delta modulator chip. Via increasing the order of the one-bit bandpass sigma–delta modulation algorithm up to 12 and using finite repetitious bitstream approximating scheme, it can achieve great improvements in signal bandwidth instead of purity at the cost of very little hardware overhead. Another contribution in this work is to provide the theoretical analysis of the reconstructed signal degradation due to harmonic distortion and clock jitter. Such on-chip analog stimulus generation scheme is especially fit for IF digitizing bandpass sigma–delta modulator chip's production-time testing and in-the-field diagnostics. The technique can also be extended to mixed-signal communication SoC built-in-self-test.

Continuous time quadrature band-pass ΔΣ modulator with input mixers

A continuous time quadrature band-pass ΔΣ modulator preceded by input mixers is presented. Complex band-pass ΔΣ modulators provide better performance than band-pass ΔΣ modulators in digitising complex signals due to more efficient noise shaping (Yantzi et al., 1997). Continuous time implementation of the second-order ΔΣ noise shaping loop filter is preferred to a switched capacitor structure (van der Zwan and Dijkmans, 1996). Through the integration of mixers in the AD converter, RF input signals in the range 0.3–1.6 GHz can be down-converted to a digital I and Q output stream at a clock rate of 128 MHz. It is designed as a front-end for a low power receiver with a 2 MHz IF bandwidth centred around 4 MHz and attains a signal-to-noise ratio higher than 60 dB. The ΔΣ ADC and mixer are integrated in a 0.25 μm CMOS technology and consume 14 mW from a 2 V supply

IF properties of YBCO hot-electron bolometer mixers for millimeter-wave radiation

Slot antenna coupled YBa 2Cu 3O 7− δ (YBCO) hot-electron bolometer mixers for 94 GHz millimeter-wave radiation were fabricated. Temperature dependencies of the detected voltage and the temperature derivation of the resistance (d R/d T) were measured in the video detection at 94 GHz. The detected voltage dominated by the bolometric effect, which was proportional to the d R/d T, was obtained. On the other hand, the nonbolometric response, which was caused by the flux creep effect, was also observed in the vicinity of the critical temperature ( T c). In the heterodyne mixing at 94 GHz the IF bandwidth of the device, whose response was dominated by the nonbolometric process, was about 1.0 GHz. This value was higher than that of the YBCO bolometer mixer whose response was dominated by the phonon escape time.

IF bandwidth and noise temperature measurements of NbN HEB mixers on MgO substrates

We report the fabrication and testing of hot electron bolometric mixers with an ultrathin NbN film as heterodyne receivers operating at terahertz frequencies. We found that the quality of the NbN strip is usually degraded by damage resulting from the fabrication process, and we developed a process for reducing such damage. We also fabricated HEB mixers with a new structure in order to study the IF bandwidth determined by the original quality of the NbN thin films. Investigations at 100 GHz revealed that the widest IF bandwidth of 2.0 GHz was obtained by a mixer based on a 2.8 nm-thick NbN film. An HEB mixer based on the 2.8 nm-thick NbN film was also fabricated and evaluated. The receiver noise temperature at 900 GHz was 780 K, the absorbed LO power was about 400 nW, and the conversion gain was -13 dB.