O. Schmitz

Inductorless Low-Voltage and Low-Power Wideband Mixer for Multistandard Receivers

This paper presents the design and implementation of a low power wideband mixer for multistandard receivers, covering global system for mobile communications, universal mobile telecommunications system, wireless local area network, Bluetooth, and ultra-wideband. The circuit topology is based on the folded technique with a current reuse shunt feedback RF input stage operating at a low supply voltage of 1 V. The mixer offers a peak gain of 12.8 dB, a 3-dB bandwidth from 1 to 10.5 GHz, and a minimum double-sideband noise figure of 7.6 dB. The input referred compression point is better than -15 dBm with an output referred intercept point of better than 5.75 dBm over the entire bandwidth. The mixer circuit was fabricated in a 65-nm standard CMOS process and draws 5 mA of dc current, leading to a power dissipation of only 5 mW. Gain and noise performance can be further increased when operating at nominal supply voltage of 1.2 V at the expense of an increasing power dissipation.

Inductorless 1–10.5 GHz wideband LNA for multistandard applications

This article presents the design of a fully integrated inductorless LNA for wireless applications including WLAN, Bluetooth and UWB. The circuit was fabricated in 65nm CMOS technology and operates at a supply voltage of 1.2 V. The two-stage design is comprised of a current reuse shunt feedback input stage followed by a differential pair, incorporating an active inductor load to compensate the gain roll-off. The circuit exhibits a peak gain of 16.5 dB, while the 3-dB bandwidth as well as the input and output matching of better than −10 dB range from 1–10.5 GHz. The noise figure is kept below 5 dB within this frequency range, offering a minimum noise figure of 3.9 dB. The linearity in terms of P1dB, out and oIP3 offers nearly constant behavior with −5 dBm and 3 dBm respectively. The active area takes up only 0.021 mm2.

9-GHz Wideband CMOS RX and TX Front-Ends for Universal Radio Applications

Wideband receiver (RX) and transmitter (TX) RF front-ends for wireless universal radio applications are presented. The RX is comprised of a two-stage low-noise amplifier (LNA) applying feedback and shunt peaking, a combiner buffer for performance boosting, and an inverter-based in-phase/quadrature (IQ) down-conversion mixer. The wideband LNA provides input matching of better than -10 dB from dc to beyond 10 GHz. The conversion gain (CG) of the RX front-end has a peak value of 31 dB with a 3-dB bandwidth up to 9 GHz. The minimal noise figure is 6 dB and kept below 9 dB within the entire operational bandwidth. The RX has a linearity in terms of intermodulation distortion of better than -12 dBm. The direct conversion TX involving inverter-based IQ modulator and Darlington-type pre-power amplifier features operation up to 9 GHz with 10-dB mean CG and an average output power of 4 dBm at 1-dB compression level. Excluding buffers and local oscillator generation, the RX and TX dissipate 54 and 84 mW, respectively, from a 1.2-V voltage supply. The circuit prototypes have been fabricated in a standard 65-nm CMOS low-power process without any additional RF options and occupy an area of only 0.77 mm2 and 0.53 mm2, respectively.

Low-Voltage Bulk-Driven Mixers in 45nm CMOS for Ultra-Wideband TX and RX

This paper presents fully differential up-and down-conversion mixers manufactured in a triple well 45 nm standard CMOS process for low voltage UWB TX and RX applications. The proposed circuits both employ the transistor bulk terminal for signal injection. While the RX mixer uses the bulk for switching via threshold voltage modulation, the TX mixer applies the baseband signal to the bulk. Both circuits offer resistive on-chip termination and DC coupled output buffering for measurement purposes. The RX mixer features a maximum conversion gain of 9.4 dB at 2.5 GHz and an input-referred compression point of -13 dBm while the 3-dB low-pass bandwidth is beyond 10 GHz. The TX mixer offers a maximum conversion gain of -8.8 dB at 5.5 GHz and an output-referred compression point of -10.3 dBm. The operational bandwidth ranges from 4.5 GHz to 7 GHz. Both circuits operate at a low voltage power supply of 1.1 V.

Low-voltage, inductorless folded down-conversion mixer in 65nm CMOS for UWB applications

This paper presents the design and implementation of a low-voltage down-conversion mixer in 65nm CMOS technology for UWB applications. The folded circuit topology with AC-coupled inverter based RF transconductance stage operates under low voltage conditions of 1.2 V with a peak gain of 14.5 dB and a 3-dB-bandwidth from 1 GHz to 10.5 GHz with 1 dBm LO power. The input referred compression point is better than −16.5 dBm with an oIP3 of 7 dBm at 2 GHz. The minimum DSB noise figure is 6.5dB with a flicker-noise corner frequency of 2 MHz. The mixer draws 12 mA from a power supply of 1.2 V leading to a power dissipation of only 14.4mW.

Wideband inductorless minimal area RF front-end

This paper presents the design of a fully integrated inductorless wideband RF front-end for wireless applications including WLAN, Bluetooth and UWB. The core of the circuit is comprised of a two stage LNA, followed by a standard Gilbert cell mixer and an output buffer for measurement purposes. The chip was fabricated in 65nm standard CMOS process. The RX offers an input matching of better than −10 dB in a bandwidth from 2.1 GHz to 8.2 GHz. To compensate the gain roll off the LNA incorporates an active inductor load, leading to a peak conversion gain of 20 dB at 3.5 GHz with a 3-dB bandwidth covering the whole matching frequency range. The minimal noise figure is 5.85 dB and kept below 7.5 dB within the whole matching and gain bandwidth. The linearity in terms of P1dB,out and oIP3 offers nearly constant behavior with −2 dBm and 7 dBm respectively. Excluding the buffer the circuit dissipates 47 mW. The die size of 370 µm by 570 µm is mainly dominated by the pad-frame, while the active area takes up only 0.05 mm2.

Differential Amplifier Characterization Using Mixed-Mode Scattering Parameters Obtained From True and Virtual Differential Measurements

This paper examines the differences in large signal mixed-mode scattering parameter characterization of differential amplifiers arising from virtual and true differential probing. The analysis is carried out by means of differential gain compression curves obtained from exemplary amplifier test assemblies with variable common mode rejection ratio. Based on analytical derivations involving basic nonlinear circuit theory, mathematical closed form transfer functions of these amplifiers are presented that enable an a-priori estimation of the occuring measurement error. Numerical simulations complete the theoretical investigations by giving additional physical insights onto the individual amplifier nodal voltages effecting the compression. Experimental results obtained from true and virtual differential compression curve measurements of the considered amplifier topologies are finally compared to the results gained from the theoretical considerations. Based on these results, the reason for the deviation between virtual and true differential measurements is addressed and upper and lower bounds for these deviations are given that are in accordance with the results reported in literature.

Polarization diversity analysis of dual-polarized log.-per. planar antennas

Antenna systems for broadband polarization diversity reception rank among the emerging key technologies in next generation wireless communication systems. In order to suppress multipath conditioned polarization fading in typical applications of portable radios, antenna modules with dual-polarized transmission behavior are to be used. Self-complementary, logarithmically-periodic antennas serve as suitable representatives for the realization of broadband antenna structures and can be favorably used in polarization diverse transmission systems. Applying usual diversity combination techniques at the receiver, high diversity gains could be achieved over a wide frequency band incorporating planar, dual-polarized log.-per. four-arm antennas

Impact of Sievenpiper High Impedance Surfaces on the Performance of Planar Cross-Dipole Polarization Diversity Antennas

This paper examines the influence of so called Sievenpiper High Impedance Surfaces (HIS) on the diversity performance of planar dual linear-polarized cross-dipole antennas in the ISM-band at 5.5 GHz. Starting from uncoupled free-space considerations we investigate characteristic performance criteria such as Mean Effective Gain (MEG), power imbalance, spatial correlation and diversity gain of different antenna configurations by means of full-wave electromagnetic analysis. Diversity analysis is performed via Monte-Carlo simulations applying statistical channel models. The obtained results show that the application of Sievenpiper High Impedance Surfaces to planar diversity antennas enables equivalent diversity performance when compared to configurations with plain ground metalizations at the same time reducing the overall-height substantially.

A highly linear, differential gyrator in 65nm CMOS for reconfigurable GHz applications

This work presents the design, implementation and measurement results of a novel, gyrator-based active inductor circuit in a 1.2 V 65nm CMOS technology. By solely employing stacked nMOS-pMOS transistor combinations, the proposed differential gyrator achieves a maximal self-resonance frequency of approximately 18 GHz and features high linearity with a current consumption of only 6 mA, therefore representing an attractive candidate for radio-frequency applications. The proposed active inductor is combined with additional circuitry and switchable capacitors in order to form an inductorless, reconfigurable RF amplifier. The comparison of measurement and simulation data in terms of scattering parameters and output referred compression verifies the active inductors functionality.