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This paper presents the circuit techniques to achieve superior linearity and isolation for a single-pole six-throw transmit/receive (T/R) switch designed for GSM/W-CDMA dual-band operation at 0.85–0.9 and 1.8–1.9 GHz. Implemented in a 0.18-\mum thick-film silicon-on-insulator (SOI) CMOS process, the switch employs an LC-tuned asymmetric topology for the transmit (Tx) and receive (Rx) branch to handle the high-power GSM transmitter requirement. The proposed design also features a switchable double LC-tank acting as a variable impedance block to relax the tradeoff among linearity, insertion loss (IL), and isolation. Feed-forward capacitors, ac-floating bias techniques, and floating-body SOI devices are utilized to further improve the linearity. The measured P-0.1\ {dB}, IL and Tx–Rx isolation in the lower and upper band are 37.2–35.6 dBm, 0.43–0.75 dB, and 45–37 dB, respectively. The proposed T/R switch design in SOI CMOS is an important building block toward more compact and lower cost RF frond-end modules, which integrate the switch, antenna tuning module, and control logic on the same chip. [ABSTRACT FROM AUTHOR]

Bitstream transmitters based on bandpass or envelope delta–sigma modulation promise high power efficiency for broadband communications with nonconstant-envelope modulations, but at the price of elevated quantization noise. An active noise filtering technique is proposed in this paper to address the quantization noise issue of such transmitters. The essential concept of active noise cancellation is to utilize multiple power amplifiers (PAs) with identical or similar transfer characteristics fed with the same input, but with different time delays. The difference in time delay determines whether the outputs of the PAs are combined in phase or out of phase at a certain frequency, which forms the passband or the stopband of the active filter. The active noise filtering technique can potentially replace the external high-Q passive bandpass filter typically needed for such transmitters. A two-channel bitstream transmitter with active noise cancellation operating at the $X$ -band is fabricated with 0.25- \mu \text{m} discrete GaN HEMT devices. It has been demonstrated experimentally that the proposed active noise filtering architecture effectively suppresses quantization noise as expected and delivers a 34.5-dBm output power with 37.6% drain efficiency and 30% power added efficiency for a single-channel WCDMA signal with 100-MHz bandwidth and 5.3-dB peak-to-average ratio. Adjacent channel leakage power ratio (ACLR) at 100-MHz offsets is measured to be 36.6/35.4 dBc without using digital predistortion. [ABSTRACT FROM AUTHOR]

This paper proposes a simple but relatively accurate, receive (Rx)-band-noise estimation method for wideband code division multiple access (WCDMA) handset heterojunction bipolar transistor MMIC power amplifier module (PAM) design. The method is based on small-signal and two-tone large-signal simulations, calculating Rx-band noise and helping circuit designers comprehend noise contributions under a large output power operation. Its effectiveness is verified through the simulations and measurements of a WCDMA band 11/21 MMIC PAM featuring an LC trap circuit placed at the base terminal of the first stage. This trap is designed to resonate at the difference frequency between the transmit- and Rx-bands. The PAM accommodating switchable-amplifier chains for triple-power modes—high power mode (HPM), mid-power mode (MPM), and low-power mode (LPM)—is fabricated using our in-house GaAs BiFET process. Measurements conducted under 3.4 V and 1450-MHz-band WCDMA (Third Generation Partnership Project Release 99, 3GPP R99) modulated signals show an Rx-band noise level of less than −136 dBm/Hz and power gain as high as 30 dB at a high output power ( P\mathrm {{out}} ) of 29 dBm. The measured noise level is in good agreement with that of the proposed estimation. The measurements also show that the PAM achieves power-added efficiency (PAE) as high as 41% at the P\mathrm {{out}} of 29 dBm while maintaining the ±5-MHz-offset adjacent channel power ratio (ACLR1) below −40 dBc in the HPM. The PAE values of 22% at P\mathrm {{out}} of 18 dBm and 17% at 7 dBm are obtained in the MPM and LPM, respectively, with the same ACLR1 levels. [ABSTRACT FROM PUBLISHER]

This paper describes a newly developed Si/GaAs hybrid multiband power amplifier module (MB-PAM) that supports major quad wideband code division multiple access (WCDMA) bands (Bands 5, 8, 2, and 1) for handset applications. With four dies (two GaAs-HBT dies, one GaAs-HEMT die, and one CMOS die) and several surface-mount devices, the hybrid MB-PAM accommodates two amplifier chains and two single-pole double-throw HEMT band-select switches on a 5 mm\,\times\, 5.5 mm laminate, covering 824–915 and 1850–1980 MHz. Each amplifier chain has two switchable signal paths corresponding to dual (high and low) power modes [high-power mode (HPM) and low-power mode (LPM)] for saving battery current in practical handset use. One of the main features of this MB-PAM is the integration of driver stages, RF switches, and their bias control circuits on the CMOS die for pursuing cost reduction. Only the two output power stages are fabricated in a GaA-HBT process. Measurements conducted under the condition of a 3.4-V supply voltage and a WCDMA (Third Generation Partnership Project Release 99) modulated signal are as follows. Owing to optimized linear design and broadband output matching design, the hybrid MB-PAM achieves a power-added efficiency (PAE) as high as 39%–40% at 28 dBm of output power ( Pout) over 824–915 MHz in the HPM while maintaining a \pm \5-MHz-offset adjacent channel leakage power ratio (ACLR1) to less than -\39 dBc. In the LPM, PAE of 15% at a Pout of 17 dBm is obtained while ACLR1 of less than -\40 dBc is maintained. For 1850–1980 MHz, the MB-PAM delivers 35% of PAE with ACLR1 of less than -\40 dBc at 28 dBm of Pout in the HPM and 15% PAE at 17.5 dBm of Pout in the LPM. [ABSTRACT FROM PUBLISHER]

A transmitter (TX) leakage canceller is proposed for improving the dynamic range of the receiver (RX) for wideband code division multiple access applications. A TX leakage canceller circuit in this paper is simple in implementation and has low noise figure (NF) contribution. It is a feed-forward canceller that samples a reference signal from the TX output and injects the amplitude-adjusted and phase-rotated signal to the RX chain. The canceller circuit is integrated with a low-noise amplifier and implemented in a 0.18-\mu\m CMOS technology. A cancellation of 23 dB is achieved with only 10-mA current consumption increase and low NF increase. [ABSTRACT FROM PUBLISHER]

This paper presents a dual-mode multiband transceiver with DigRF interface implemented in a 0.13-\mu\m CMOS technology. Based on direct conversion architecture, blocks in the transceiver can be configured to simultaneously support wavelength code-division multiple access (WCDMA) band I and four Global System for Mobile Communications (GSM) bands (PCS/DCS/GSM900/GSM850). In the receiver path, the narrowband radio-frequency front-end is comprised of multiple-gated low-noise amplifiers with capacitive desensitization and current-mode passive mixers with the proposed second-order input intercept point (IIP2) calibration to comply for surface-acoustic-wave-less application. In the transmitter path, a high-linearity mixer and parallel Class-AB PA driver are adopted. Low-noise wideband frequency synthesizers with adaptive frequency calibration are proposed to cover all modes and bands. This reconfigurable transceiver achieves -\5.6/-\2/- 6~\dBm in-band third-order intercept point for WCDMA/GSM HB/GSM LB respectively, and > \65~\dBm IIP2. At the maximum output power, the transmitter achieves 2.3% rms error vector magnitude for WCDMA I and 1.67^\circ phase error for a GSM system. [ABSTRACT FROM AUTHOR]

A real-time adaptive digital predistortion system (RT-ADPD) for power amplifier linearization is described in this paper, featuring fast closed-loop adaptation to provide robust linearity across quickly shifting power amplifier (PA) operating conditions. The RT-ADPD system requirements, architecture, and its design methodology are analyzed in detail, with particular emphasis on the optimization of the feedback loop convergence speed and stability. A novel, compact algorithm to achieve rapid adaptation of the predistortion lookup tables, without any prior knowledge of the PA distortion characteristics, is introduced. A prototype of the RT-ADPD system is implemented using a field-programmable gate array (FPGA), and it is experimentally exploited to linearize a handset WCDMA PA module. Due to the linearization action, the PA maximum modulated output power is increased by 1.9 dB, to 30.9 dBm, and its power-added efficiency by 9%, to 48.5%, still maintaining a -40-dB ACPR at a 5-MHz offset. In addition, a true closed-loop adaptation ensures excellent PA linearity under load mismatch and other environmental variations. Indeed, ACPR is improved by up to 15 dB, below -47 dB, under 2:1 VSWR at 28 dBm. Remarkably fast adaptation speed is also demonstrated, as adequate signal fidelity is achieved within a \sim\!\! \50-\mu\s time frame. [ABSTRACT FROM AUTHOR]

This paper presents a novel 2-D digital-predistortion (2-D-DPD) technique that is applicable for linearization of concurrent dual-band transmitters. This technique uses a unique way for distortion compensation and linearization of dual-band transmitters by selecting, characterizing, and applying predistortion in each band separately. Compared to conventional linearization techniques, this 2-D-DPD method requires a lower sampling rate for digital-to-analog and analog-to-digital converters. The performance of the 2-D-DPD topology is evaluated using two modulated signals, Worldwide Interoperability for Microwave Access and wideband code-division multiple-access, separated in frequency by 100 MHz. The measurement results show an adjacent channel power ratio of less than -50 dBc and a normalized mean square error of less than -40 dB. [ABSTRACT FROM AUTHOR]

This paper presents a preliminary investigation of orthogonal frequency coding (OFC) surface acoustic wave tags and sensors at a 500- and 900-MHz operational frequency range using conventional contact lithography techniques. The higher frequency devices are achieved using second harmonic operation; eliminating the need for advanced lithography techniques. The objective of this effort is to increase the technology readiness level of wideband OFC tags at higher frequencies. Measured device results are presented and compared with coupling of modes model predictions to demonstrate performance. The fundamental and harmonic device response is compared for devices designed for operation in the 900-MHz frequency band. The experimental correlation against an ideal matched filter is also presented. [ABSTRACT FROM AUTHOR]

An improved envelope equalization technique to enhance the efficiency of envelope injection and termination RF power amplifiers (PAs) is proposed. A TriQuint heterostructure field-effect transistor PA, which draws 100 mA from an 8.0-V supply and provides maximum power of 28 dBm for a continuous-wave input at 1.95 GHz, exhibits a significant improvement in the maximum linearity compliant efficiency from 21% to 28% using the proposed technique for an uplink WCDMA signal with 6.9-dB peak-to-average power ratio. The equalization improves the amplifier linearity by reducing the clipping distortion extending the maximum linear output power by more than 1 dB. A technique to maintain high efficiency, even at low average powers, is also described. [ABSTRACT FROM AUTHOR]

This paper presents a highly efficient polar transmitter using interleaving pulse modulation for multiple communication standards. Using the proposed interleaving pulse modulation technique, a polar transmitter can suppress the odd-order output spurs deeply with a feasible value of essential sampling frequency and keep the residual spurs from falling into the receive bands. To validate the proposed technique, a prototype polar transmitter was constructed and evaluated. Using global system for mobile communications, enhanced data rates for GSM evolution, and wideband code division multiple access (WCDMA) signals at 836.5 MHz, the polar transmitter achieved 68%, 45.5%, and 41.2% power-added efficiency at output power levels of 28, 26, and 25 dBm, respectively. The measurement results were able to pass the spectral requirements defined by the respective standards without the use of any pre-distortion or calibration techniques. Moreover, the polar transmitter was able to achieve an output dynamic range of 80 dB required by the WCDMA standard. [ABSTRACT FROM AUTHOR]

Ultra-wideband (UWB) is an effective technique that enables coexistence with other radio systems using very short pulses and spread spectrum. However, there are potential interferences among those using the same frequency bands. This paper discusses the effects of interference between pulse-based UWB (p-UWB) and other systems: continuous wave, binary phase-shift keying signal, IEEE802.11a wireless LAN using a 5-GHz band, and multiband orthogonal frequency-division multiplexing (MB-OFDM). The MB-OFDM is inferentially proposed for personal area networks, as is p-UWB. The FCC has stated that both p-UWB and MB-OFDM systems will use the same band from 3.1 to 10.6 GHz. The bit-error-rate performance is shown assuming that p-UWB and the other systems are utilized at close range. To mitigate the effects of interference to p-UWB from other radio systems, a multicarrier template wave technique is proposed. The multicarrier template wave is approximated with an ordinary pulse waveform by Gabor transform formula and is composed of several subband pulses without interfering bands. The proposed UWB receiver for MB-OFDM interferences can detect their hopping pattern without a priori knowledge from the MB-OFDM transmitter. These techniques are shown to be effective for the systems to coexist. [ABSTRACT FROM PUBLISHER]

The current ultra-wideband (UWB) channel models proposed by different research groups are generally based on measurements in which the effect of the antennas used are inevitably embedded. There is potentially significant waveform distortion by UWB antennas, and it is difficult to distinguish between antenna and real propagation path effects in many of the reported channel measurements. However, understanding these effects is important for overall system performance prediction. The discone antenna is known for its broadband characteristics and has been widely used for channel measurements. In this paper, we address the importance of the antenna and indoor propagation effects as applied to a UWB system analysis. This is achieved by use of a true time-domain three-dimensional ray-tracing propagation model coupled with accurate simulation of the time-domain performance of the discone antenna. A DS-UWB system approach was adopted for detailed study and its performance is evaluated under the channel model with and without considering the antenna pattern effect. Both line-of-sight and non-line-of-sight cases are considered. The antenna effect can be seen to be significant, leading to the conclusion that interpretation of practical system measurements must allow for the antennas being used in the measurement system. [ABSTRACT FROM PUBLISHER]

A single-chip multimode multiband receiver is designed and implemented in a 90-nm CMOS process for fourth-generation mobile platforms. The receiver includes nine primary low-noise amplifier (LNA) and five secondary LNA input ports, and supports long-term evolution (LTE)/WCDMA/ehanced general packet radio serve (EGPRS) standards for four gobal system for mobile communications bands, ten WCDMA bands, 14 frequency division duplex LTE band, and two time division duplex LTE bands. From antenna to RX digital signal processing output, the receiver achieves a typical 3-dB noise figure for all standards and bands. The RF front-end includes a matching network with 12-dB transducer gain, an inductively degenerated common-source LNA, passive mixers driven by a 25% duty-cycle local oscillate, and a current conveyor followed by a baseband filter. This receiver RF/analog front-end meets surface-acoustic-wave-less linearity requirements for all LTE/WCDMA bands and employs digital calibration to adjust the baseband low-pass filter cutoff frequency, mixer image rejection, second-order intermodulation intercept point performance and to perform in-phase/quadrature equalization. [ABSTRACT FROM PUBLISHER]

A deep space satellite downconverter receiver was proposed by Jet Propulsion Laboratory (JPL) and NASA Lewis Research Center (LeRC) for the Naval Research Laboratory's (NRL) high temperature superconductivity space experiment, phase-II (HTSSE-II) program. Space qualified low-noise cryogenic downconverter receivers utilizing thin-film high temperature superconducting (HTS) passive circuitry and semiconductor active devices were developed and delivered to NRL. The downconverter consists of an HTS preselect filter, a cryogenic low-noise amplifier; a cryogenic mixer, and a cryogenic oscillator with an HTS resonator. HTS components were inserted as the front-end filter and the local oscillator resonator for their superior 77 K performance over the conventional components. The semiconducting low noise amplifier also benefited from cooling to 77 K. The mixer was designed specifically for cryogenic applications and provided low conversion loss and low power consumption. In addition to an engineering model, two space qualified units (qualification, flight) were built and delivered to NRL. Manufacturing ,integration and test of the space qualified downconverters adhered to the requirements of JPL class-D space instruments and partially to MIL-STD-883D specifications. The qualification unit has /spl sim/50 K system noise temperature which is a factor of three better than a conventional downconverter at room temperature. Commercial applications such as intersatellite links and V-SATS are envisioned to benefit by >3 dB link margin, or a factor of 2 in antenna size, from a future hybrid HTS/semiconducting cryogenic receiver employing new InP based HEMT LNA. In a spread spectrum communication network, the number of users per beam would more than double. [ABSTRACT FROM AUTHOR]