Linear Mixer Research Articles

Piston attenuator as RF signal vernier in the 10-300 MHz range: determination and correction of spurious mode errors

Systematic errors in H11-mode piston attenuators from unwanted mode excitation have been measured for CW, and pulse modulated RF signals as well, up to 300 MHz with a new calibration circuit based on a linear RF-IF mixer. The attenuation deviation by spurious mode influence can be calculated from the determined amplitude ratio of superposed modes and can be corrected. In this way piston attenuators, originally designed for IF application, can also be used as RF verniers with 0.01 dB resolution up to 300 MHz and possibly higher with an accuracy depending on mixer linearity in the calibration circuit.

Universal liquid chromatography methods : IV. Use of 190-mm full gradients by adjustment of eluent ultraviolet absorbance and pH with gases

The full-gradient “universal liquid chromatography” methods are extended to 190 nm detection for even greater sensitivity and detection of more components than shown previously at 210 nm. Universal liquid chromatography offer major time/costs savings by increasing problem solving throughout. Further, at 190 nm, simple molecules such as aliphatic alcohols are detected and 254-nm detectable species are quantified to much lower levels. Universal liquid chromatography “elutes-all” in a first wide-polarity, full gradient run and “detects-all” with low wavelength (less than 214 nm) UV and permits easy resolution changes. A single universl method replaces many different tailored isocractic runs for first-run-problem-solving of most mixtures. These methods eliminate method development for each new problem and also permit unattended runs of totally different separation problems. Universal methods permit rapid product, mix, or raw material comparisons of good vs. bad, new vs. old, or starting vs. purified materials while signaling new components that might not be seen in the narrow polarity window of isocratic runs. “Injection loading” of ion-pairing agent is also extended to 190 nm. This allows rapid run-to-run change in selectivity and exploration of ion-pairing effects plus determination of charges of ionic species. A new “gas baseline adjustment” method allows very simple eluent preparation to fix pH and give flat, ghost-peak-free baselines. A new method is given to calibrate detectors at all wavelengths and a simple “linear mixer” eliminates short-term baseline noise.

Frequency Conversion and Limiter Action for an Angle-Modulated Wave With Amplitude Fluctuation in a Half-Wave Linear Mixer

Signal interaction is analyzed when the composite signal of a simultaneously amplitude- and angle-modulated wave, a nonmodulated sinusoidal wave, and a noise is added to a half-wave linear mixer. If a certain mixing condition is satisfied, a half-wave linear mixer operates like an ideal bandpass limiter with frequency conversion function. The limiter action is also verified by experiment.

Injection-Locked-Oscillator FM Receiver Analysis

The major components of an injection-locked-oscillator FM receiver are a linear mixer and a van der Pol type of negative resistance oscillator in a phase-locked configuration. In this paper the nonlinear differential equation describing the receiver output is solved and explicit expressions obtained for the output signal, noise, and controlling second and third order distortions. The input signal carrier is both amplitude and frequency modulated. Signal-to-distortion ratios have been computed and are presented for the case of a noise modulated FM input signal. The results indicate that excellent performance may be expected of such a receiver.

Molecularized FM Telemetry Encoder

The objective of the Molecularized FM Telemetry Program was to provide more reliable FM subcarrier oscillators that have reduced size, weight, and power consumption. Both conventional circuit functional electronic block oscillators and the more truly molecular drift field oscillator were considered. The molecular drift field oscillator was selected. The final design for the oscillators required only one power supply (+28V). In addition, the design approaches the goal of a single design for all of the oscillators in that a standardized design for the input amplifier, feedback amplifier, output amplifier, and regulator was achieved using only one type of general purpose epitaxial monolith. Using this design, five subcarrier oscillators operating over IRIG band 11, <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">A, C, E</tex> , and <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">H\ast</tex> (7kc/s to 165kc/s) were successfully built and tested. The feasibility of operation over -20°C to +80°C was shown. In addition, the five oscillators were operated together driving a linear mixer with no intermodulation effects. These molecular oscillators have a volume that is one-ninth, weight that is one-fourteenth, and power dissipation that is one-half to one-third that of conventional transistorized FM oscillators.

Hall-effect reinforcement of high-frequency fields in semiconductors

The paper considers a number of high-frequency applications of a technique, described by Midgley, which uses Hall effect in a semiconductor to increase the penetration of an externally applied magnetic field. High-mobility semiconductors, like the intermetallic indium compounds, giving large Hall effects, also have a high conductivity with a correspondingly small skin depth, so that it becomes difficult to utilise the body of the semiconductor effectively. Hall-effect reinforcement of the applied field is therefore particularly valuable at high frequencies, and methods by which this may be exploited to advantage in Hall-effect and magnetoresistance-effect linear mixers, power-measuring devices and mode transducers, are discussed. A new form of electrically controlled attenuator embodying the same principle is also proposed.

High Stability Multiparametric Modular Circuitry used in the Experiments at the Saclay's Cyclotron

Advent of the small semiconductor detector makes easier complex multiparametric experiments which may include a great number of detectors to provide precise information on location and energy of particles. Such complex systems pose special requirements for reliable, flexible and high performance electronics. A set of modular circuits has been designed for use at the Saclay cyclotron which may be assembled easily for either simple or complex experiments. The following modular and sub-modular circuits are described: (1) charge-sensitive preamplifier module, (2) highly stable gain, low noise, 15 nsec minimum rise time charge-sensitive preamplifier submodule, (3) preamplifier-associated discriminator module, (4) 4-input, low noise, stable, low level linear mixer, (5) low level discriminator to be driven directly from the above preamplifiers, (6) precision, semi-fast high level discriminator, (7) 3-input, highly stable gain, gated linear amplifier with precision, continuously adjustable gain, (8) 4-input, high level linear mixer and biased post amplifier, (9) automatic testing system. The modules are described and the application of the modular system is illustrated in connection with nuclear spectroscopy experiments employing /g=a//g=a/'-scattering.

Resistive attenuators and their calibration

The characteristics of metallized-glass-vane attenuators in rectangular waveguide are briefly reviewed. Resetting accuracies of 0.004 and 0.012 dB in 40 dB are achieved at 3 and 10 Gc/s, respectively. The glass vanes are unaffected by extreme climatic conditions, and laboratory attenuators in the 10 Gc/s band have retained their calibration to within 0.03 dB over a five-year period.The attenuators are calibrated with reference to the accurately constructed piston attenuator of a 60 Mc/s signal generator. The microwave signal is amplitude modulated and is converted to 60 Mc/s in a linear mixer. The signal generator output is also amplitude modulated, and the two 60 Mc/s signals are compared in a phase-sensitive detector. Methods are described for the determination of the errors of calibration, and it is concluded that the total inaccuracy does not exceed 0.03 dB in the range 0–50 dB in the 3 and 10 Gc/s bands.