Low-noise Converter Research Articles

Signal-dependent pump-to-probe noise transfer due to Kerr nonlinearity in silicon ring resonators

The pump-probe configuration has been extensively implemented in silicon ring resonators (RRs) for all-optical switching and wavelength conversion. While the pump’s influence on the probe’s signal is well known, the effect of the pump on the probe’s noise has not been studied. Here, we analytically and numerically analyze the impact of the pump’s signal and noise on the probe’s noise distribution. We show that the probe’s output noise has two sources: the probe’s input noise passing through the RR’s transfer function and a new noise term generated by the RR’s transfer function fluctuations caused by the pump’s noise via the Kerr effect. Furthermore, this pump-induced noise can significantly reduce the probe’s output optical signal-to-noise ratio by up to 15 dB. As the new noise term strongly depends on the pump’s power, wavelength conversion of optical communications signals with amplitude modulation formats will result in considerable signal-dependent noise, which can greatly affect the receiver’s design and performance. In addition, the developed probe noise model can be used to design low-noise wavelength converters and switches employing silicon Kerr RRs.

CONSTRUCTION OF MICROWAVE RADIOMETERS BASED ON SATELLITE LOW NOISE CONVERTERS

Particularities of construction of millimeter-wave band and centimeter-wave band radiometers based on satellite low noise converters (SLNB) are examined. Operation characteristics of the experimental stand of the cm-band radiometer are presented based on the satellite low noise block. The calibration method is suggested. The experimental results are compared with the published data. The possibility of using SLNB as an HF intermediate amplifier of mm-band radiometers and two-bandwidth radiometers is examined. Conclusions are made about the reasonability of application of SLNB for construction of radiometers and other receiving devices.

Resource Allocation for Cognitive Satellite Communications With Incumbent Terrestrial Networks

The lack of available unlicensed spectrum together with the increasing spectrum demand by multimedia applications has resulted in a spectrum scarcity problem, which affects satellite communications (SatCom) as well as terrestrial systems. The goal of this paper is to propose resource allocation (RA) techniques, i.e., carrier, power, and bandwidth allocation, for a cognitive spectrum utilization scenario where the satellite system aims at exploiting the spectrum allocated to terrestrial networks as the incumbent users without imposing harmful interference to them. In particular, we focus on the microwave frequency bands 17.7–19.7 GHz for the cognitive satellite downlink and 27.5–29.5 GHz for the cognitive satellite uplink, although the proposed techniques can be easily extended to other bands. In the first case, assuming that the satellite terminals are equipped with multiple low block noise converters (LNB), we propose a joint beamforming and carrier allocation scheme to enable cognitive space-to-Earth communications in the shared spectrum where fixed service (FS) microwave links have priority of operation. In the second case, however, the cognitive satellite uplink should not cause harmful interference to the incumbent FS system. For the latter, we propose a joint power and carrier allocation (JPCA) strategy followed by a bandwidth allocation scheme, which guarantees protection of the terrestrial FS system while maximizing the satellite total throughput. The proposed cognitive satellite exploitation techniques are validated with numerical simulations considering realistic system parameters. It is shown that the proposed cognitive exploitation framework represents a promising approach for enhancing the throughput of conventional satellite systems.

A wide-band RF front-end for multiband multistandard high-linearity low-IF wireless receivers

A wide-band radio-frequency (RF) front-end is designed with a balanced combined low-noise amplifier and a switching mixer (a low-noise converter) in an RF Si-bipolar process with an f/sub T/ of 25 GHz. The circuit achieves 20-dB conversion gain, higher than -4.5-dBm RF-to-IF IIP/sub 3/ (+15.5-dBm OIP/sub 3/) and less than 3.8-dB double-side-band noise figure in 900-MHz (e.g., GSM) and 1.9-GHz (e.g., WCDMA) frequency bands. The -1-dB compression point is -20 dBm at 13-mA DC current consumption from a single 5-V supply. The local-oscillator leakage to the input is less than -56 dBm in the 900-MHz band and less than -63 dBm in the 1.9-GHz band. The -3-dB bandwidth of the amplifier is larger than 3 GHz and a wide-band matching at the input with -10 to -41-dB S/sub 11/ is achieved in the frequency bands of interest by applying a dual-loop wide-band active feedback. The die area is 0.69 /spl times/ 0.9 mm/sup 2/. The circuit is suitable for area-efficient multiband multistandard low-IF receivers.

Power factor improvement technology by means of resonant type converter circuits

It is desired to develop soft-switching power factor improvement technology and put it into practical use by means of a high-efficiency, low-noise, and low-cost resonant-type converter. Every technology that has been developed so far has many disadvantages alongside its advantages and leaves problems to be solved before it can be put to practical use. This paper presents the configuration of a partial capacitor input rectifier circuit using soft-switching operations that we have developed as a power-feedback-type one-converter circuit. The technology allows us to implement practical power factor improvement for consumer-use electronic products. © 1998 Scripta Technica, Electr Eng Jpn, 125(4): 67–74, 1998

Low noise multiwasher superconducting interferometer

The dc-superconducting quantum interference device (SQUID) is a low-noise converter from magnetic flux to voltage which can have, in principle, an energy sensitivity near the quantum limit of ℏ/2. A critical parameter for the ideal performance is the device inductance, which must be kept as small as possible. Minimizing the SQUID inductance, however, is a major concern for a practical device; this requirement implies a small SQUID ring and hence magnetic coupling with an external signal is more difficult to achieve. Here we present an original scheme (called multiwasher) to circumvent this problem, and its implementation in an all-refractory thin-film device. Our scheme not only provides good magnetic coupling with a large input coil (0.5 μH) and very low SQUID inductance, but also shielding from outside uniform fields, such as those generated by ambient disturbances. The measured coupled spectral energy sensitivity in the white region at about 1 kHz is 28ℏ at 4.2 K and 5.5ℏ in a pumped helium bath at 0.9 K. The flux noise spectral density at 0.1 Hz and 0.9 K is Φn=1×10−6 Φ0/Hz.

New Method to Determine the a-Si:H Pin Diode Series Resistance by Noise Measurements

ABSTRACTThe series resistance limits the linearity of photodiodes and decreases the efficiency of solar cells. It is usually determined from IV-measurements for moderate and high forward current density. This method, however, provides only partial information about Rs, since the series resistance depends on the operating point. An alternative method is based on noise measurements. System noise of the measuring system with a low-noise current-voltage converter has been investigated. A new method for extraction of photodiode series resistance from noise measurements is suggested. Noise measurements are carried out for a-Si:H pin diodes. The series resistance of an amorphous pin diode has been extracted for different operating conditions using the new measurement method.

Waveguide-to-coupled fin-line transition in Ka band

A new broadband transition from waveguide-to-coupled fin-line in its quasi-TEM mode is presented. The transition is proposed for low-noise amplifiers or low-noise converters in millimeter-wave bands. Experimental results on the Ka band show a 1 dB insertion loss for a back-to-back double transition over a 10 GHz band.

New type of DBS receiver utilizing optical fiber as IF transmission line

An optical fiber transmission system that transmits the IF signal for direct broadcasting satellite (DBS) TV channels from a low noise converter to the main chassis of the DBS receiver after the IF signal at 1 GHz is converted into the corresponding second IF signal at 300 MHz (35-335 MHz) is described. The differential gain and differential phase of the video signal are less than 2% and 3 degrees, respectively, and the signal-to-noise ratio (SNR) is 45 dB. >

A 30 GHz MMIC receiver for satellite transponders

The development of 30-GHz-band monolithic microwave integrated circuits (MMICs) and multichip MMIC modules (low-noise amplifier and frequency converters) is reported. A 30-GHz-band full-MMIC receiver for satellite transponders was successfully constructed using the MMIC modules and the performance of the full-MMIC receiver is evaluated. Test results verify its successful performance as a satellite receiver system. The design and performance of the MMICs (a two-stage amplifier, an image rejection mixer, and a frequency multiplier), of multichip-type MMIC modules (a 30-GHz-band low-noise amplifier module with 30 dB gain and 8.2 dB noise figure, and an image rejection frequency converter with a 10 dB conversion loss and an 18 dB image rejection ratio) and of the full-MMIC receiver, which weighs 1/6 as much as a conventional hybrid integrated circuit are presented. >

Direct Broadcast Home Terminals — A Status Report

This article examines the rapidly emerging direct broadcast satellite (DBS) service as a medium which promises to deliver not only consumer satellite service but a host of new technologies as well. Various aspects of the new technology are discussed, including the development of antennae, the role of gallium arsenide in the low-noise converter for satellite reception, and the practical considerations of interfacing with a growing number of home video services. The practical applications of the service are reviewed as DBS affects the future of the broadcasting industry.

12-GHz-Band GaAs Dual-Gate MESFET Monolithic Mixers

12-GHz-band GaAs dual-gate MESFET monolithic mixers have been developed for use in direct broadcasting satellite receivers. In order to reduce chip size, a buffer amplifier has been connected directly after a mixer IF port, instead of employing an IF matching circuit. The mixer and the buffer were fabricated on separate chips, so that individual measurements could be achieved. Chip size is 0.96X 1.26 mm for the mixer and 0.96X0.60 mm for the buffer. A dual-gate FET for the mixer, as well as a single-gate FET for the buffer, has a closely spaced electrode structure. Gate length and width are 1 µm and 320 µm, respectively. The mixer with the buffer provides 2.9+-0.4-dB conversion gain with 12.3+-0.3dB SSB noise figure in the 11.7-12.2-GHz RF band. Local oscillator (LO) frequency is 10.8 GHz. A low-noise converter was constructed by connecting a monolithic preamplifier, an image rejection filter, and a monolithic IF amplifier to the mixer. The converter provides 46.8+-1.5-dB conversion gain with 2.8+-0.2-dB SSB noise figure in the same frequency band.

A 12 GHz Low Noise Converter for Two Band Reception

A 12 GHz low, noise converter (LNC) suitable for use in two band reception has been developed. A wideband, very low noise amplifier (LNA) and two Switchable local oscillators in the LNC make it possible to receive two frequency bands. The developed LNC has low noise figures of less than 2.5 dB (for frequency band from 11.7 to 12.2 GHz) , a high image rejection ratio of more than 90 dB, and very low local power leakage of less than -95 dbW.

Simdified 12-GHz Low-Noise Converter with Mounted Planar Circuit in Waveguide (Short Papers)

A 12-GHz low-noise converter consisting of a planar circuit mounted in waveguide is described. This circuit consists of a metal sheet with proper patterns that is inserted in the middle of a waveguide parallel to the E plane. All circuit elements required for the converter are pressed or etched. This circuit is very useful for low-cost mass production and good performance. A measured noise figure of 4.5 dB was obtained with a 12-GHz signal frequency and a 420-MHz intermediate frequency.

Negative Resistance Devices Using A Multiple Number of Tunnel Diodes or Varactors

The critical need for simple high-gain, low-noise microwave amplifiers and frequency converters, required for space communication and improved ground communication systems, appears to be met by the solid-state tunnel diode and varactor devices. The incorporation of these low-noise negative resistance devices results in significant improvement in the performance of communication systems where sensitivity is of importance. Past attention has been concentrated mainly on negative resistance devices using a single tunnel diode or varactor. This paper will present some results on devices using a multiple number of tunnel diodes or varactors. The behavior of devices using an arbitrary number of diodes in either a nonreciprocal or reciprocal environment is studied and compared with the single-diode configurations. For an amplifier using n tunnel diodes with parameters ( - R_{1}, C_{1} ), ( -R_{2}, C_{2} ), ...,( - R_{n}, C_{n} ), the optimum gain-bandwidth limitation for a nonreciprocal configuration is given by (G_{T})_{n}\leq \exp [\sum \min{r=1} \max {n} \frac{2\pi}{\omega_{c}R_{r}C_{r}] where (G_{T})_{n} is the fiat transducer power gain and ω c is the bandwidth in rad/s for the amplifier using n tunnel diodes. This optimum gain-bandwidth limit can be realized by cascading n stages of the optimum nonreciprocal single-diode amplifiers. For the reciprocal realization of the tunnel diode amplifiers, it can be shown that irrespective of the number of tunnel diodes employed, the optimum nonreciprocal matching can never yield more than 6 dB over the optimum reciprocal equalization. Thus, the fiat gain for the reciprocal case is given by (G_{T})_{n} \leq \frac{1}{4}[1+ exp (\sum \min{r=1} \max{n} \frac{\pi}{\omega_{c}R_{r}C_{r})]^{2} . For n varactors with parameters C or and C{1r}, r = 1,2, ..., n , the optimum nonreciprocal parametric amplifier must satisfy the following limitation (G_{T})n \leq \cosh^{2} [\frac{\pi}{\sqrt{\omega_{so}w_{io}}{\omega_{c}}(\sum \min{r=1} \max{n} \frac {C_{1r}}{C_{or}})] where \omega_{s0} and \omega_{i0} denote the signal and idler band-center frequencies respectively. This result is a generalization of the gainbandwidth limitation for single-varactor parametric amplifiers published recently by the author [1]. Besides the results on gain-bandwidth limitations, the stability of the negative-resistance devices using an arbitrary number of tunnel diodes or varactors is also studied. Since both the tunnel diode and the varactor are two-terminal active elements, they must be capable of operating in a stable manner under at least one passive termination. Although a complete stability theory for tunnel diode and varactor devices is not as yet available, some useful sufficient conditions are derived in the paper for the stability of these negative resistance devices. Results presented in the paper on the important gain-bandwidth limitations and stability conditions are useful in the design and synthesis of stable, broadband, low noise tunnel diode and varactor parametric amplifiers incorporating a multiple number of diodes. Among the many possible applications for this theory, one can cite the phased-array systems and the pseudo-passive satellite techniques. In the latter application, a large number of tunnel diode amplifier units are integrated in an antenna structure to enhance the scattering cross-section of a moderate-size structure.