Adaptive self-calibrating image rejection receiver

An adaptive self-calibrating image rejection receiver is described, containing a modified Weaver image rejection mixer and a Digital Image Rejection Processor (DIRP). The blind source-separation-based DIRP eliminates the I/Q errors improving the Image Rejection Ratio (IRR) without the need for trimming or use of power-hungry discrete components. Hardware complexity is minimal, requiring only two complex coefficients; hence it can be easily integrated into the signal processing path of any receiver. Simulation results show that the proposed approach achieves 75-97 dB of IRR

Comparison of the Image Rejection between the Passive and the Gilbert Mixer

This paper presents a comparison of the image rejection between Gilbert mixer and the passive mixer. A simple model for mixers is set up, and the image rejection performance of passive and Gilbert mixer is analyzed based on it. Simulations and calculations were done to compare the image rejection of the two mixers. The results show that the Gilbert mixer, comparing with the passive one, shows a stronger rejection to the amplitude error of the quadrature signals at its input

A CMOS Q-Enhancement Bandpass-Filter For Use In Paging Receivers

Paging receivers often have to work in a dense\ud signal environment. This poses high demands on the preselection\ud filter. One of the most difficult aspects is the large\ud image rejection demand, which only can be satisfied by use\ud of a narrow-band or high-Q filter. The practical restrictions\ud for possible filter implementations are the low cost, low\ud power and the small size of the pager. By use of positive feedback\ud around a cheap off-chip low-Q inductor we obtain an\ud enhanced quality factor. We are therefore able to construct\ud selective filters using cheap small-size inductors. The price\ud paid for Q-enhancement is a larger noise and higher sensitivity\ud to component variations. The higher noise influence\ud is eliminated using a high gain in the preceding LNA-stage,\ud which is considered a part of the filter. Simulated results\ud are: Q enhanced from 30 to 100, Image-rejection = 48dB,\ud f0 = 280MHz, Voltage-gain = 20dB, Noise- figure = 2.4dB,\ud IMFDR = 66dB, IDD = 1mA, VDD = 2V. The original contribution\ud of this work is the application of the enhancement\ud principle to off-chip components, which benefits the minimization\ud of size and cost

A New 100-GHz Band Front-End System with a Waveguide-Type Dual-Polarization Sideband-Separating SIS Receiver for the NRO 45-m Radio Telescope

We developed a waveguide-type dual-polarization sideband-separating SIS receiver system of the 100-GHz band for the 45-m radio telescope at the Nobeyama Radio Observatory, Japan. This receiver is composed of an ortho-mode transducer and two sideband-separating SIS mixers, which are both based on the waveguide technique. The receiver has four intermediate frequency bands of 4.0--8.0 GHz. Over the radio frequency range of 80--120 GHz, the single-sideband receiver noise temperatures are 50--100 K and the image rejection ratios are greater than 10 dB. We developed new matching optics for the telescope beam as well as new IF chains for the four IF signals. The new receiver system was installed in the telescope, and we successfully observed the 12CO, 13CO and C18O emission lines simultaneously toward the Sagittarius B2 region to confirm the performance of the receiver system. The SSB noise temperature of the system, including the atmosphere, became approximately half of that of the previous receiver system. The Image Rejection Ratios (IRRs) of the two 2SB mixers were calculated from the 12CO and HCO+ spectra from the W51 giant molecular cloud, resulting in > 20 dB for one polarization and > 12 dB for the other polarization.Comment: 10 pages, 13 figures, Accepted for publication in PASJ, version with high resolution figures is available via http://www.nro.nao.ac.jp/library/report/list.htm

A low-complexity feed-forward I/Q imbalance compensation algorithm

This paper presents a low-complexity adaptive feed- forward I/Q imbalance compensation algorithm. The feed-forward so- lution has guaranteed stability. Due to its blind nature the algorithm is easily incorporated into an existing receiver design. The algorithm uses three estimators to obtain the necessary parameters for the I/Q imbal- ance compensation structure. The algorithm complexity is low due to 1-bit quantization in the estimators. Simulations show that the compen- sation algorithm is able to attain an image-rejection ratio (IRR) of up to 65 [dB] under various imbalance conditions

Design of a power-aware digital image rejection receiver

This paper deals with and details the design of a power-aware adaptive digital image rejection receiver based on blind-source-separation that alleviates the RF analog front-end impairments. Power-aware system design at the RTL level without having to redesign arithmetic circuits is used to reduce the power consumption in nomadic devices. Power-aware multipliers with configurable precision are used to trade-off the image-rejection-ratio (IRR) performance with power consumption. Results of the simulation case studies demonstrate that the IRR performance of the power-aware system is comparable to that of the normal implementation albeit degraded slightly, but well within the acceptable limits

Development of the ALMA-North America Sideband-Separating SIS Mixers

As the Atacama Large Millimeter/submillimeter Array (ALMA) nears completion, 73 dual-polarization receivers have been delivered for each of Bands 3 (84-116 GHz) and 6 (211-275 GHz). The receivers use sideband-separating superconducting Nb/Al-AlOx/Nb tunnel-junction (SIS) mixers, developed for ALMA to suppress atmospheric noise in the image band. The mixers were designed taking into account dynamic range, input return loss, and signal-to-image conversion (which can be significant in SIS mixers). Typical SSB receiver noise temperatures in Bands 3 and 6 are 30 K and 60 K, resp., and the image rejection is typically 15 dB.Comment: Submitted to IEEE Trans. Microwave Theory Tech., June 2013. 10 pages, 21 figure

The sensitivity of a very long baseline interferometer

The theoretical sensitivity of various methods of acquiring and processing interferometer data are compared. It is shown that for a fixed digital recording capacity one bit quantization of single sideband data filtered with a rectangular bandpass and sampled at the Nyquist rate yields the optimum signal to noise ratio. The losses which result from imperfect bandpass, poor image rejection, approximate methods of fringe rotation, fractional bit correction, and loss of quadrature are discussed. Also discussed is the use of the complex delay function as a maximum likelihood fringe estimator

A Wideband 77-GHz, 17.5-dBm Fully Integrated Power Amplifier in Silicon

A 77-GHz, +17.5 dBm power amplifier (PA) with fully integrated 50-Ω input and output matching and fabricated in a 0.12-µm SiGe BiCMOS process is presented. The PA achieves a peak power gain of 17 dB and a maximum single-ended output power of 17.5 dBm with 12.8% of power-added efficiency (PAE). It has a 3-dB bandwidth of 15 GHz and draws 165 mA from a 1.8-V supply. Conductor-backed coplanar waveguide (CBCPW) is used as the transmission line structure resulting in large isolation between adjacent lines, enabling integration of the PA in an area of 0.6 mm^2. By using a separate image-rejection filter incorporated before the PA, the rejection at IF frequency of 25 GHz is improved by 35 dB, helping to keep the PA design wideband

Study of Passive CMOS Mixers Effects on Image Rejection Ratio

In this brief, modeling and simulation of quadrature passive mixers are analyzed, focusing on the impact they have on the image rejection ratio (IRR). For this purpose, a 65-nm CMOS technology is used