IF Amplifier Research Articles

Cryogenic All Solid-State Millimeter-Wave Receivers for Airborne Radiometry

Cryogenic receiver modules for 90 and 140 GHz have been developed that are part of an airborne imaging system. They consist of Schottky-barrier mixers followed by GaAs-FET IF amplifiers. The DSB receiver noise temperatures are 210 K for the 90-GW and 250 K for the 140-GHz system. The instantaneous bandwidth is 2.5 GHz for both front ends. Results of some flight tests are presented.

Multiple mixer, cryogenic receiver for 200–350 GHz

This paper describes a new 200–350-GHz dual polarization heterodyne radiometer receiver for radio astronomy applications. The receiver incorporates four pairs of cryogenically cooled Schottky-barrier diode single-ended mixers, each pair covering a 30–40-GHz subband of the full operating band. Each mixer, with its IF amplifier, is mounted in an individual cryogenic subdewar comprising a separate vcuum chamber and a cold stage, which may be readily thermally connected to or disconnected from the main refrigerator by a novel mechanical heat switch. A dual polarization LO diplexer is mounted on a rotary table above the subdewars. For band selection, the two diplexer rf output ports may be positioned over any of the four pairs of subdewars. The SSB receiver noise temperatues achieved are less than 500 K between 200 and 240 GHz, less than 800 K between 245 and 275 GHz and 1500 K at 345 GHz.

Communications transponder performance for Japanese Communications Satellite-2 and prospects for future systems

Communications transponder for the Japanese Communications Satellite-2 (CS-2a and 2b) to be launched into a geostationary orbit by N-II launch vehicle in February and August, 1983, has been developed. The transponder is provided with six-channel K-band ( 30 20 GHz ) transponder including beacon transmitter, which operates in the highest frequency ranges ever utilized on an operational communications satellite, and two-channel C-band ( 6 4 GHz ) transponder. Receiver front end of the K-band transponder consists of a direct mixer followed by a 1.8 GHz IF amplifier and provides 8 dB noise figure. 20 GHz output power is 4 W by final amplification at 5-W TWTA. C-band transponder provides 4 dB noise figure and 4.3-W output power. Key factors for future high capacity transponder are also presented.

Television Receiver using a Pure Synchronous Detector IC

This paper describes a new excellent video detector IC for color television receivers with phase lock loop ( PLL ) operating at the intermediate frequency of 58.75 MHz generator. The IC includes IF amplifier, AGC circuit, VCO, video processing circuit, video detector, automatic phase control ( APC ) circuit, lock-unlock condition detector and AFC circuit. Using this system, better performance than a traditional diode detector or a quasi synchronous detector has been achieved with no increase of manufacturing cost.

A Two-Stage Monolithic IF Amplifier Utilizing a Ta/sub 2/O/sub 5/ Capacitor

A two-stage monolithic IF amplifier incorporating a sputtered Ta/sub 2/O/sub 5/ capacitor has been fabricated. The monolithic capacitor is based on a composite layer structure consisting of Au, Ta, Ta/sub 2/O/sub 5/, Ta, and Au. This layered structure is sequentially deposited in a single sputtering run, which eliminates particulate contamination. As a result, a thin pinhole-free dielectric layer can be deposited over large areas, and 140-pF capacitors have been fabricated with excellent yields. The large unit area capacitance of 1500 pF/mm/sup 2/ available with the present process has the potential for reducing the size of matching and bias circuits in microwave monolithic circuits and hybrid thin-film circuits. The monolithic amplifiers exhibit a gain of 17.5 +- 1.0 dB from 1.2 to 2.6 GHz and a minimum noise figure of ~2.7 dB, with an associated gain of 17.5 dB at 1.7 GHz.

A two-stage monolithic IF amplifier utilizing a Ta2O5capacitor

A two-stage monolithic IF amplifier incorporating a sputtered Ta 2 O 5 capacitor has been fabricated. The monolithic capacitor is based on a composite layer structure consisting of Au, Ta, Ta 2 O 5 , Ta, and Au. This layered structure is sequentially deposited in a single sputtering run, which eliminates particulate contamination. As a result, a thin pinhole-free dielectric layer can be deposited over large areas, and 140-pF capacitors have been fabricated with excellent yields. The large unit area capacitance of 1500 pF/mm2available with the present process has the potential for reducing the size of matching and bias circuits in microwave monolithic circuits and hybrid thin-film circuits. The monolithic amplifiers exhibit a gain of 17.5 ± 1.0 dB from 1.2 to 2.6 GHz and a minimum noise figure of ∼ 2.7 dB, with an associated gain of 17.5 dB at 1.7 GHz.

An Integrated Video IF Amplifier and PLL Detection System

A second-generation Phase Locked Loop (PLL) synchronous detector has been successfully combined with a high gain IF amplifier and automatic gain and frequency control (AGC and AFC), to form a high performance video IF system on a 105 x 114 mil die in a 28 pin package. Integration of these functions together in the same package required in excess of 80dB of isolation at 45MHz. Research indicated that the dominant coupling mode would be mutual inductance within the package wirebonds and leadframe, and that side-to-side isolation was superior to end-to-end isolation. This experience was applied to the die layout and placement resulting in a system which is able to acquire lock below viewable signal levels.

All Solid-State Low-Noise Receivers for 210-240 GHz

Low-noise all solid-state receiver systems for room temperature and cryogenic operation between 210 and 240 GHz are described. The receivers incorporate a single-ended fixed tuned Schottky barrier diode mixer, a frequency-tripled Gunn source as local oscillator and a GaAsFET IF amplifier. Single sideband receiver noise temperatures are typically 1300 K (7.39-dB noise figure) for a room temperature system and 470 K (4.18-dB noise figure) for a cryogenically cooled receiver operating at 20 K.

A Complete Single Chip AM/FM Radio Integrated Circuit

We have developed a carmlete single chip AM/FM radio integrated circuit embodying all the necessary function for an AM/FM radio system. It includes the AM/FM front end, AM/FM IF amplifiers, AM AGC, AM/FM detector, audio pre and power airplifiers, variable capacitor diode for the FM AFC, tuning indicator circuit, electric volume, as well as a regulated supply. As a result, the application of this IC enables a complete AM/ FM radio system without any use of active ccmponents.

Analysis of Image Recovery Down Converter Made by Planar Circuit Mounted in a Waveguide

This paper presents an analysis of a superhigh frequency (SHF) down converter using a Schottky-barrier mixer diode and a planar circuit mounted in a waveguide. The analysis assumes that the mixer diode consists of a nonlinear conductance g, a junction capacitance C/sub j/, an ohmic spreading resistance R/sub s/, and several parasitic susceptances. The frequency performance of the impedance of external circuits at the signal, image, and intermediate frequency bands is considered. This analysis also includes consideration of the mismatching effect between the converter and the IF amplifier, and the optimum design procedure for the down converter. Using this theoretical method, a SHF down converter was designed and constructed. Its application is low noise receivers for satellite broadcasting. The design used the optimum image condition (the image impedance takes a low value, i.e., nearly a short). The RF band is 11.7 - 12.2 GHz, the IF band is 0.96 - 1.46 GHz, and the total noise figure is 3.3 - 3.7 dB. The noise figure is in good agreement with the (3.2 - 3.6 dB) obtained from this analysis.

A 26-GHz Band Integrated Circuit of a Double-Balanced Mixer and Circulators

Integration of a double-balanced mixer and ferrite-disk type circulators have been successfully achieved in the 26-GHz band. The total single-sideband noise figure of the integrated circuit, composed of a mixer and two circulators, is 8.5 dB, including the noise contribution from an IF amplifier. The double-balanced mixer is composed of microstrip lines, slot lines, coupled slot lines, coplanar lines, Au wires, and four beam lead Schottky-barrier diodes. The minimum conversion loss of the mixer is 5.3 dB at a signal frequency of 25.4 GHz. Isolation between RF and LO ports is greater than 30 dB. The ferrite-disk type circulator is produced by a newly developed precise machining technique. The minimum insertion loss of the circulator is 0.45 dB, and the isolation is greater than 20 dB. The integrated circuit with the ferrite-disk type circulators will be extended to the millimeter-wave band.

A GaAs monolithic low-noise broad-band amplifier

Describes the design, fabrication, and performance of GaAs monolithic low-noise broad-band amplifiers intended for broadcast receiver antenna amplifier, IF amplifier, and instrumentation applications. The process technology includes the use of Czochralski-grown semiinsulating substrates, localized implantation of ohmic and FET channel regions, and silicon nitride for passivation and MIM capacitors. The amplifiers employ shunt feedback to obtain input matching and flat broad-band response. One amplifier provides a gain of 24 dB, bandwidth of 930 Mhz, and noise figure of 5.0 dB. A second amplifier provides a gain of 17 dB, bandwidth of 1400 MHz, and noise figure of 5.6 dB. Input and output VSWR's are typically less than 2:1 and the third-order intercept points are 28 and 32 dB, respectively. Improved noise figure and intercept point can be achieved by the use of external RF chokes.

94-GHz Beam-Lead Balanced Mixer

Using a newly developed GaAs beam-lead diode, we have developed and evaluated a balanced mixer at 94 GHz. The various components of the mixer were separately optimized using carefully designed low-frequency model studies as our primary design aid. These studies included the determination of guide impedance and guide wavelength for suspended stripline, and optimization of a waveguide to suspended stripline transition, low-pass filters, and diode location. This 94-GHz mixer exhibits an average single sideband (SSB) conversion loss of 6.2 dB over a 6-GHz RF bandwidth. Together with a bipolar IF amplifier, the system exhibits a 4.5-5.1-dB double sideband (DSB) noise figure over a 50-700-MHz IF bandpass. LO-to-RF isolation was greater that 27 dB over this range of operating frequencies. Finally, severe environmental test were successfully performed on the mixer between sucessive electrical characterization.

Airborne Imaging System Using a Cryogenic 90-Ghz Receiver

A cryogenic 90-GHz receiver has heen developed with a noise figure of 2.36 dB ((double sideband) (DSB)) and an instantaneous band-width of 1.2 GHz. The cooled front-end consists of a Schottky-barrier mixer followed by a GaAs FET IF amplifier. The radiometer is small in size and weighs only 52 kg, including the refrigerator system. It is part of an airborne imaging system, that has been fight-tested aboard a Dornier Do 28 aircraft. First test results are presented.

Precision Saw Filters For A Large Phased-array Radar System

The electronically steerable radar (ELRA) at the Forschungsinstitut fur Funk und Mathematik is an experimental S-band phased-array radar system consisting of separate transmitting and receiving arrays employing several coherent and incoherent signal-processing and data-handling techniques, incorporating multiple beam and multifunction operation for target search and tracking, adaptive interference suppression, and target resolution. This paper deals with the development and application of two types of SAW filters for the IF amplifier channel of the receiving array. Compared to conventional filters with lumped elements, these filters have some important merits. By making use of a special tuning technique, the center frequencies of all filters were adjusted, resulting in an rms deviation of less than 1 kHz. One type of the SAW filters represents an almost ideal approach of realizing a matched filter for rectangular shaped pulses. The conformity of the frequency responses of several hundred filters improved the noise suppression capability of the system. The use of the filters described represents one of the applications where high-quality mass-produced SAW devices have been applied to improve system reliability and performance.

Development of VHF/FM Radio Front end Integrated Circuit

Recent years have witnessed an wide application of integrated circuits for radio receivers, with use including audio amplifiers, FM/AM IF amplifiers, FM/AM detectors, AM/RF amplifiers, mixers and FM stereo-demodulators. Moreover, a paper (1) describes a single chip AM/FM IC radio in which several of the above-mentioned functions have been integrated into a single chip.

A 1-Bit Digital Autocorrelator

In this paper, we present a 1-bit method of computing autocorrelation functions. The experimental set-up of a 40-channel 1-bit autocorrelator developed at the Physical Research Laboratory, Ahmedabad is presented. Using noise input, the correlator was tested in conjunction with the 70-MHz IF amplifier, which forms a part of an RF spectral line receiver developed for the purpose of detecting OH emissions at 18-cm wavelength from interstellar hydroxyl molecules. Two sets, one of 7 and the other of 50 minutes of integration time, of test observations were analysed to compute autocorrelation functions and power spectra. It is concluded that the highest accuracy of spectral measurements would be achieved provided the latter are made in the flat region of the response of the band-pass filter.

Monolithic Integrated VHF TV Tuner

Using an NSA (Nitride Self-Aligned) bipolar process with 4 GHz fT transistors, a monolithic frequency converter IC was developed, which consisted of a local oscillator, mixer, IF amplifier, UHF-IF amplifier, AGC amplifier and voltage regulator.

Improved Method of Automatic Gain Control for Wideband Low Noise if Amplifier

This paper discusses some of the considerations which are involved in a wideband low-noise transistor IF amplifier when an automatic gain control is used to hold its output constant. The design of a satisfactory pulsed IF gain control amplifier is described and measured performance data is shown by means of curves.This article presents an improved method of applying AGC to the wideband IF amplifier that overcomes, to a great extent, the problems that have plagued previous AGC circuits. It is hoped that this circuit will be of value in application of transistor amplifier for use in superheterodyne receivers.

A novel beam lead GaAs Schottky-barrier diode fabricated by using thick polyimide film

A novel beam lead GaAs Schottky-barrier mixer diode with high performance has been developed for use in super high frequency (SHF) receiving system. The parasitic capacitance of the diode has been reduced to 0.03 pF by using thick polyimide insulating film formed by improved etching techniques. The series resistance has been lowered to 0.5 Ω by a liquid-phase double epitaxial method of growing an n-n++active layer on an n+wafer. The total diode capacitance at zero bias has been lowered to 0.15 pF using a 10-µm junction diameter. An n factor of less than 1.10 was obtained. The calculated cutoff frequency including parasitic capacitance exceeds 2000 GHz. Several reliability tests including temperature cycling in high humidity show good results. In an SHF downconverter consisting of a waveguide which contains a planar circuit, the diode was attached to the planar circuit by means of an intermediate plate, despite the small diode dimensions of 0.75 mm by 0.22 mm. An overall noise figure (NF) as low as 4.3 dB, and conversion loss as low as 3.0 dB were achieved at 12 GHz (IF range of 290-470 MHz and IF amplifier NF of 1.5 dB). These values are shown to be satisfactory for application to a low-noise receiving system for satellite TV broadcasting.