Image Rejection Ratio Research Articles

1024-QAM High Image Rejection $E$-Band Sub-Harmonic IQ Modulator and Transmitter in 65-nm CMOS Process

An E-band high image-rejection sub-harmonic in-phase/quadrature (IQ) modulator for a high-order quadrature amplitude modulation (QAM) signal is designed and implemented on standard 65-nm CMOS technology. To maintain high image-rejection ratio of the IQ modulator over a wide bandwidth for high data-rate application, a load-insensitive analysis and a local oscillator (LO) broadband 45° power splitter are proposed to achieve low amplitude and phase imbalanced structure. In addition, the doubly balanced sub-harmonic Gilbert-cell mixer with the advantages of good LO leakage suppression has been selected in the mixer design. The IQ modulator demonstrates a measured flat conversion gain of 0 ± 1 dB from 55 to 85 GHz. The image rejection ratio is better than 40 dBc from 64 to 84 GHz. For millimeter-wave communication applications, the IQ modulator is integrated with a four-stage power amplifier to form a direct-conversion transmitter. The measured conversion gain of the transmitter is 33 dB and the measured saturated power is 11 dBm. Via high image rejection and good LO suppression of the modulator, a 1024-QAM modulated signal with a data rate of 500 Mb/s and 1.7% error vector magnitude is successfully demonstrated at 65 GHz.

DESIGN OF LOW-VOLTAGE LOW-POWER COMPLEX ACTIVE-RC FILTERS

In this paper, novel realization of low-voltage low-power active-RC complex filters is presented. The previously proposed method to compensate for opamp non-idealities in real active-RC filter design, which is suitable for low-power low-voltage application, is extended such that it can be used in the case of complex filter design. Subsequently, fifth-order Chebyshev complex filter with 1-MHz center frequency, bandwidth and 0.5-dB bandpass ripple has been designed for Bluetooth application. Simulation results show that the designed complex filter consumes about 1 mW under 1-V single supply. Its image rejection ratio (IRR) and out-of-band third-order input intercept point (IIP3) are about 80 dB and 37.5 dBV p respectively.

EVM Analysis for Broadband OFDM Direct-Conversion Transmitters

Low-cost orthogonal frequency-division multiplexing (OFDM) direct-conversion transceivers suffer from signal degradation through the impairments of the analog front end, e.g., due to in-phase and quadrature (IQ) imbalance, phase noise, and nonlinear power amplifier (PA) effects. This paper analyzes joint performance degradation due to these key transmitter imperfections. Error vector magnitude (EVM) is chosen as the figure of merit, which is motivated by its frequent use in the standards for specifying transmitter requirements. In particular, we derive closed-form EVM expressions for the challenging problem of wideband OFDM transmitter design and validate the analysis through simulations. Based on the study, it is possible to conclude that EVM is governed by the memory effects associated with the PA and the reciprocal of the image rejection ratio (IRR), which is defined by the IQ modulator. We also demonstrated that intercarrier interference (ICI) due to the local oscillator phase noise shows an approximately frequency-flat response.

A Nonrecursive Digital Calibration Technique for Joint Elimination of Transmitter and Receiver I/Q Imbalances With Minimized Add-On Hardware

A nonrecursive digital calibration technique, namely, local oscillator (LO) switching, is proposed for jointly eliminating transmitter (TX) and receiver (RX) I/Q imbalances in one combined process. The add-on analog parts are limited to a set of source followers (0.00228 mm2) and metal-oxide-semiconductor (MOS) switches (0.00017 mm2 ) for reusing the 90 ° phase shift property of the reference LO, avoiding the sinusoidal test tone, loop-back detector, high-speed analog-to-digital converter, and 2-D iterative search algorithm, mostly required in the prior art. A 65-nm complementary MOS transceiver, which is codesigned with a field-programmable-gate-array-based coordinate rotation digital computer algorithm, measures a 10-dB improvement in the image rejection ratio of both the TX (27.8 → 37.2 dB) and the RX (31.2 → 42 dB). The required digital circuitry for the algorithm is also assessed and simulated.

A 65-nm GSM/GPRS/EDGE SoC With Integrated BT/FM

A quad-band GSM/GPRS/EDGE cellular system, implemented in 65-nm CMOS, is integrated in a multimedia SoC with BT and FM. A low-IF receiver with digital IRR tracking is selected for its smaller area and better noise figure. The receiver achieves a sensitivity of <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$-$</tex> </formula> 110 dBm, an IIP3 of <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$-$</tex> </formula> 9.5 dBm, and a calibrated image rejection ratio of 65 dBc, while consuming 61 mA. The polar transmitter architecture is chosen for its SAW-less TX capability, smaller area, and low current consumption. It achieves an ORFS (output radio frequency spectrum) of <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex Notation="TeX">$-$</tex></formula> 68 dB and <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex Notation="TeX">$-$</tex></formula> 64 dB at 400 kHz in GMSK and EDGE mode, respectively, while consuming 61 mA. The loop gain normalization, dc offset and AM/PM delay of the polar system are compensated to be better than 1% error, 1 mV, and 1.9 ns within 170 <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex Notation="TeX">$\mu$</tex></formula> s, respectively. Several techniques are employed to minimize interference coupling within the SoC; these include frequency planning, circuit implementation, transceiver architecture optimization, and digital clock selection. The measured sensitivity and the output spectrum of the three wireless systems under full-feature phone operation are virtually unchanged.

Efficient adaptive compensation of I/Q imbalances using spectral coherence with monobit kernel

This paper shows a new algorithm to improve the performance of IQ demodulators and frequency converters exhibiting gain and phase imbalances between their branches. This algorithm does not require any input calibration signal and is independent of the input signal level. It exploits the spectral coherence (SC) concept using a monobit kernel to achieve optimization targets with minimum time to convergence, low computational load, and a wide range of input levels. Its effectiveness is shown through a low-IF receiver that improves its image rejection ratio (IRR) from 30 dB to 60 dB.

Design of an Optimal Layout Polyphase Filter for Millimeter-Wave Quadrature LO Generation

The analysis and design of a two-stage passive RC polyphase filter for millimeter-wave quadrature local oscillator generation is presented. The layout parasitics, which significantly deteriorate the filter performance at millimeter-wave frequencies, are identified with the help of impedance variation and transfer function analysis. To alleviate this parasitic degradation, a new optimal layout structure along with parasitic-compensation technique is proposed, which results in a 15-dB improvement in image rejection ratio, as compared with a conventional layout. Using the proposed techniques, more than 35 dB of image rejection over a bandwidth of 7 GHz is demonstrated in an outphasing transmitter at 60 GHz in 40-nm CMOS.

A New 100-GHz Band Two-Beam Sideband-Separating SIS Receiver for Z-Machine on the NRO 45-m Radio Telescope

ABSTRACTWe have developed a two-beam waveguide-type dual-polarization sideband-separating SIS receiver system in the 100-GHz band for z-machine on the 45-m radio telescope at the Nobeyama Radio Observatory. The receiver is intended for astronomical use in searching for highly redshifted spectral lines from galaxies of unknown redshift. This receiver has two beams, which have 45″ of beam separation and allow for observation with the switch in the on-on position. The receiver of each beam is composed of an ortho-mode transducer and two sideband-separating SIS mixers, which are both based on a waveguide technique, and the receiver has four intermediate frequency bands of 4.0–8.0 GHz. Over the radio frequency range of 80–116 GHz, the single-sideband receiver noise temperature is lower than about 50 K, and the image rejection ratios are greater than 10 dB in most of the same frequency range. The new receiver system has been installed in the telescope, and we successfully observed a 12CO (J = 3–2) emission line toward a cloverleaf quasar at z = 2.56, which validates the performance of the receiver system. The SSB noise temperature of the system, including the atmosphere, is typically 150–300 K at a radio frequency of 97 GHz. We have begun a blind search of high- J CO toward high- z submillimeter galaxies.

460 μW 32 dB image rejection ratio second‐order active‐RC complex filter with improved power efficient opamp

An ultra-low-power second-order Chebyshev active-RC complex filter for a low-IF ultra-low-power receiver is presented. By utilising a pole-cancellation push-pull buffer with feedforward phase compensation technology, the operational amplifier (opamp) realises superior stability while maintaining high gain bandwidth and ultra-low power consumption. A second-order complex filter with four proposed opamps and an adaptive bias fabricated in standard 180 nm CMOS process consumes only 460 μW at 1.8 V power supply. The measured centre frequency is 3 MHz and bandwidth is 2 MHz, while it achieves 32 dB image rejection ratio at the centre frequency.

Image-rejection receiver using on-chip active notch filters for 2.4-GHz band wireless communication applications

This paper presents the design and experimental results of image-rejection (IR) receiver front-end for 2.4-GHz band applications. The proposed IR-receiver front-end integrates a third-order active notch filter into each of conventional cascode low noise amplifier and down-conversion mixer to achieve high image-rejection ratio (IRR). The image signal is suppressed and the wanted signal is maximized due to series and parallel resonator effects of the notch filter, respectively. Consequently, the proposed IR-receiver front-end implemented in a standard 0.18 μm CMOS technology has the power gain of 21.5 dB, the noise figure of 3.5 dB, the input third order intermodulation product of ?15 dBm and the IRR of 56 dB. The IR-receiver front-end dissipates a total of 5.5 mA from supply voltage of 1.8 V.

G&lt;sub&gt;m&lt;/sub&gt;-C Complex Band-Pass Filter with Tuning Circuit in 0.18μm CMOS

This paper presents a 0.18μm CMOS based Gm-C complex band-pass (CBP) filter with tuning circuit. Active-Gm-C structure with Nauta transconductor and phase-locked loop (PLL) architecture are adopted by the filter and the tuning circuit respectively which can achieve accurate frequency response. The layout size is 970μm×920μm. Under a 1.8V supply voltage, measurement results show that the pass-band gain and the ripple of the filter is 3.1dB and 3dB respectively. The bandwidth after tuning is 32.5MHz, image rejection ratio (IRR) is about 47dB, and the power dissipation of the filter is about 21.6mW.

Development of Superconducting Spectroscopic Array Receiver: A Multibeam 2SB SIS Receiver for Millimeter-Wave Radio Astronomy

We have developed a 3 <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$\times$</tex></formula> 3 multibeam sideband separation superconducting receiver—Superconducting Spectroscopic Array Receiver (SSAR)—for the 85–115 GHz frequency band. The receiver employs 2SB superconductor–insulator–superconductor (SIS) mixers with a typical single sideband (SSB) noise temperature of 60 K and image rejection ratio above 10 dB over the frequency band. Digital techniques are extensively applied in this receiver system for excellent operational stability and efficiency. They include fast Fourier spectrometers, digital LO and digital bias supplies. In our knowledge this is the first 2SB multibeam millimeter wavelength receiver in the world. This receiver has been successfully put into observation and its considerable enhancement of mapping speed has been demonstrated.

다중 접합 기반 수신기의 영상 제거비 평가 및 향상 방법

본 논문에서는 다중 접합 기반 수신기 (MPDR)의 영상 제거 성능을 향상시키는 반복적인 단일주파수 CW 신호 기반 I/Q 신호 재생 알고리즘을 제안한다. 이 논문에서는 MPDR 수신기의 I/Q 신호 재생이 직접변환수신기의 I/Q 부정합 보상임을 보인다. 분석을 바탕으로 I/Q 재생의 정확도를 영상 제거비로써 평가한다. 제안한 방법은 기존의 I/Q 신호 재생 방법에 비해서 20dB 이상 영상 제거비를 향상시킨다. 모의실험 결과는 제안한 방법을 이용한 MPDR 수신기의 영상 제거비가 70dB 이상임을 보이고, 비트오율 성능은 페이딩 채널 환경에서 조차도 일반적인 동기 수신기의 성능과 거의 같음을 보인다.

A 6–20 GHz Adaptive SiGe Image Reject Mixer for a Self-Healing Receiver

A wideband (6–20 GHz) Silicon-Germanium (SiGe) adaptive image-reject mixer with an intermediate frequency (IF) of 1.8 GHz is presented. The mixer can be “self-healed” to deliver consistent performance by nullifying the effects of process variations, environmental changes, or aging. Various performance metrics of the mixer can also be adapted to different specifications across multiple frequency bands. A conversion gain greater than 15 dB, an image rejection ratio (IRR) exceeding 35 dB, and an output 1-dB compression point greater than 10 dBm, were obtained in measurement. An automated self-healing procedure is developed and shown to be effective for improving the measured performance of the mixer. The mixer was fabricated in a 150 GHz peak <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$f_{T}$</tex></formula> , 200 nm SiGe BiCMOS process technology and consumes 215 mA of current operating off a 4 V rail.

A Dual-Channel Compass/GPS/GLONASS/Galileo Reconfigurable GNSS Receiver in 65 nm CMOS With On-Chip I/Q Calibration

A fully integrated dual-channel reconfigurable GNSS receiver supporting Compass/GPS/GLONASS/Galileo systems is implemented in 65 nm CMOS. The receiver incorporates two independent channels to receive dual-frequency signals simultaneously. GNSS signals located at the 1.2 GHz or 1.6 GHz bands are supported, with their bandwidths programmable among 2.2 MHz, 4.2 MHz, 8 MHz, 10 MHz, and 18 MHz. By implementing a flexible frequency plan with a low/zero-IF architecture and reconfigurable analog baseband circuits, only one frequency synthesizer is required to provide the local oscillator (LO) frequency for two channels, thereby avoiding any LO crosstalk. Analog baseband circuits employ operational amplifiers that are capable of power scaling, in order to minimize power consumption across different operating modes. An I/Q mismatch calibration module placed prior to the complex-IF bandpass filter is implemented to improve the image rejection ratio. The receiver achieves a minimum 1.88 dB noise figure, an average 50 dB image rejection ratio, and a 64 dB dynamic range with 1 dB steps of gain-adjustment, with a total power consumption of 31-44 mW. Finally, experimental verification combining both the receiver and a digital baseband shows a positioning result comparable to commercial chips.

한국우주전파관측망 129 GHz 초전도 믹서 수신기

We have developed superconducting mixer receivers for 129 GHz VLBI observation in Korean VLBI Network (KVN). The developed mixer has a radial waveguide probe with simple transmission line L-C transformer as a tuning circuit to its 5 series-connected junctions, which can have 125 - 165 GHz as the operation radio frequency (RF). For intermediate frequency (IF) signal path a high impedance quarter-wavelength line connects the probe to one end of symmetric RF chokes. The double side band (DSB) receiver noise of the mixer was about 40 K over 4 - 6 GHz IF band, whereas we achieved the uncorrected single side band (SSB) noise temperature of about 70 K and better than 10 dB image rejection ratio in 2SB configuration with 8 - 10 GHz IF band. Insert-type receiver cartridges employing the mixers have been under commission for KVN stations.

Development of a 385–500 GHz Sideband-Separating Balanced SIS Mixer

A submillimeter (385-500 GHz) low-noise sideband-separating balanced SIS (Superconductor Insulator Superconductor) mixer (Balanced 2SB mixer) with high IRR (Image Rejection Ratio) has been successfully developed, whose SSB (Single SideBand) noise temperature is similar to 200 K (10hf/k) with an image rejection ratio of a parts per thousand yenaEuro parts per thousand a1/410 dB. Balanced mixers have become a promising technology which would break through the limitation especially in terahertz receivers and heterodyne arrays. However, though there are examples in microwave with relatively worse noise performance, submillimeter and terahertz balanced mixers have rarely been developed in spite of their astronomical importance. The developed balanced 2SB mixer is not only the first one demonstrated at submillimeter frequency range, but also has very low noise, high IRR, wide detectable frequencies (385-500 GHz), and a flat IF output spectrum. The balanced 2SB mixer is composed of three RF hybrids, four DSB (Double SideBand) mixers, two 180A degrees IF hybrids, and an IF quadrature hybrid. Several important performance indicators such as noise temperature, IRR, required LO (Local Oscillator) power, and IF spectra were measured. The measured LO power required for the balanced 2SB mixer was typically similar to 14 dB less than that of the single-ended mixers.

Adaptive IF selection and IQ mismatch compensation in a low-IF GSM receiver

This paper presents an algorithm that can adaptively select the intermediate frequency (IF) and compensate the IQ mismatch according to the power ratio of the adjacent channel interference to the desired signal in a low-IF GSM receiver. The IF can be adaptively selected between 100 and 130 kHz. Test result shows an improvement of phase error from 6.78° to 3.23°. Also a least mean squares (LMS) based IQ mismatch compensation algorithm is applied to improve image rejection ratio (IRR) for the desired signal along with strong adjacent channel interference. The IRR is improved from 29.1 to 44.3 dB in measurement. The design is verified in a low-IF GSM receiver fabricated in SMIC 0.13 μm RF CMOS process with a working voltage of 1.2 V.

A CMOS adaptive RF front-end receiver for wireless applications

Design and implementation of an image-rejection double-quadrature radio frequency front-end receiver based on tunable polyphase filters (PPF) are presented in this article. The front-end consists of two sets of PPFs and a double-quadrature down-converter. The design contains devices that allow process spread and frequency drift control, making it suitable for multi-standard applications. Formal analysis and statistical method leading to the polyphase filter optimal sizing have been dealt with in this article. The effects of parasitic capacitances and component mismatch are also considered and discussed. Steps within CMOS polyphase filter design flow are then provided to guarantee high image rejection ratio (IRR) performance. The front-end receiver exhibits more than 60 dB IRR and good linearity in high-frequency applications.

Power-Scalable, Complex Bandpass/Low-Pass Filter With I/Q Imbalance Calibration for a Multimode GNSS Receiver

A power-scalable reconfigurable filter with in-phase/quadrature (I/Q) imbalance calibration for a multimode Global Navigation Satellite Systems (GNSS) receiver is presented. The filter is reconfigurable as either a fifth-order complex bandpass filter exhibiting a tunable intermediate frequency (4.092, 6.138, 10.23, 12.296, 13.29, 18.4, and 20.442 MHz) and bandwidth (2.2, 4.2, 8, 10, and 18 MHz) or a third-order low-pass filter with tunable bandwidth (5 and 9 MHz). A flexible current-reuse operational amplifier with a power-scaling technique is proposed to lower the power consumption, and the image-rejection ratio is improved by almost 20 dB by introducing an I/Q imbalance calibration circuit before the filter. The filter, which was implemented in 65-nm CMOS, consumes 2.9-19.5 mW in different modes, with the I/Q calibration circuit consuming 0.9 mW.