Abstract: The present invention relates to an apparatus and methods for performing chemical reactions. In particular, the present invention relates to an apparatus for heating chemical reaction mixtures. The apparatus applies one or more semiconductor based microwave generators making the apparatus suitable for parallel processing of chemical reaction mixtures. The invention further relates to methods for performing chemical reactions, e.g. methods for heating a plurality of samples simultaneously or sequentially, methods for monitoring a microwave heated chemical reaction, and methods where the optimum conditions with respect to parameters, such frequency and applied power can be determined for the system consisting of apparatus plus sample.

Abstract: A technique capable of improving speed of a set operation, which controls writing rate in a semiconductor device including a memory cell using a phase-change material. The technique uses means for setting a set-pulse voltage to be applied to the phase-change material to have two steps: the first-step voltage sets a temperature of the phase-change memory to a temperature at which the fastest nucleation is obtained; and the second pulse sets the temperature to a temperature at which the fastest crystal growth is obtained, thereby obtaining solid-phase growth of the phase-change material without melting. Moreover, the technique uses means for controlling the two-step voltage applied to the phase-change memory by a two-step voltage applied to a word line capable of reducing the drain current variation.

Abstract: A batteryless, portable frequency divider, such as used in presence detection systems for article surveillance or as used for article-location determination, includes a series LC resonant circuit connected directed across a parallel LC resonant circuit. One circuit is resonant at a first frequency and the other circuit is resonant at a second frequency that is a plural-integer-divided quotient of the first frequency. In one class of embodiments, either or both of the series and parallel resonant circuits includes a variable capacitance element, such as a varactor, in which the capacitance varies in accordance with the voltage across the variable capacitance element. The variation of the capacitance of the variable capacitance element in response to variations in energy in the higher-frequency resonant circuit resulting from receipt electromagnetic radiation at the first frequency causes the lower-frequency resonant circuit to transmit electromagnetic radiation at the second frequency.

Abstract: An integrated varactor diode frequency multiplier assembly including a first varactor diode frequency multiplier circuit having a non-stepped waveguide output, a second varactor diode frequency multiplier circuit having a non-stepped waveguide input and a non-stepped waveguide for integrally connecting the output of the first circuit to the input of the second circuit, wherein the impedance level of the input of the second circuit is similar to the impedance level of the output of the first circuit.

Abstract: A frequency multiplier which employs a step recovery diode operated in a double pulse mode for each period of the cycle of the input frequency signal provides efficient and high order harmonic generation. The bias circuitry for the diode and impedance characteristics of the input and output bandpass filters are selected to provide stable operation.

Abstract: The invention relates to a broad bandwidth frequency divider which converts a band of input frequencies into a band of output frequencies such that each output frequency is one half the corresponding input frequency. The frequency divider has a first rectangular waveguide which propagates the band of input frequencies and a second larger rectangular waveguide which propagates the band of output frequencies. The two waveguides are orthogonally disposed with respect to one another and are interconnected by a slot provided in a common wall. Two nonlinear capacitive reactances are mounted in the first waveguide, one on each side of the slot, forming a transverse resonator. When the two nonlinear reactances are pumped in phase at the input frequency, parametric subharmonic resonance can be excited transversely at one half the input frequency such that the nonlinear reactance voltages are 180.degree. out of phase at the output frequency.

Abstract: A broad band frequency divider in which microstrip or stripline transmission lines and more than one microwave varactor diodes are interconnected to form a circuit which is resonant at a frequency of one-half of the input signal frequency and whose output consists substantially of odd order harmonics of one-half of the input frequency, the even order harmonics being virtually eliminated. An unbalanced output signal is achieved through the use of a coplanar balun. An optional DC external bias may be applied to the varactor diodes.

Abstract: A harmonic mixer utilizing an anti-parallel configuration of two diodes which, when excited by a voltage waveform V.sub.LO sin .omega..sub.LO t + V.sub.s sin .omega..sub.s t where V.sub.LO is much greater than V.sub.s, yields a terminal current having angular frequency components m .omega..sub.LO .+-. n .omega..sub.s with the restriction that m + n is an odd integer. The diode configuration results in low conversion loss mixing when the local oscillator frequency is a subharmonic of the usually required local oscillator frequency, suppression of local oscillator noise sideband effects without the use of filters or hybrid junctions, and suppression of direct video detection.

Abstract: A varactor multiplier circuit is driven by a pulsed source of radio frequency and self-biased such that it operates in its snap condition to generate harmonic frequencies. The output pulse has essentially the same configuration and length as the input pulse. These pulse envelopes may have a relatively slow voltage build-up with time. A separate bias drive circuit is directly connected to the varactor and provides a negative-going pulse of sufficient voltage to bias the varactor to its off condition. This gating bias pulse is variable as to pulse width and is very steeply rising and serves to either turn on or cut off the varactor sharply to thus provide a shaped envelope of the output wave form. An isolating capacitor and a band stop filter operate to prevent loading of the multiplier circuit by the bias drive circuit and to prevent radio frequency leakage into the drive circuit.

Abstract: A precisely controlled bandpass/bandstop filter is fabricated by coupling open circuit stubs to a transmission line. The first and second stubs are designed to resonate with the third stub at the center frequency of the passband. Both the first and third stubs are one quarter wavelength long at the center frequency of the stopband, thereby attenuating transmission line signals within this band. The second stub is of a predetermined dimension to attenuate signals at a flyback frequency which occurs within the stopband as a result of interreaction between the stubs.In a particular application, the filter may be used to significantly enhance the signal to noise characteristic of the mixer portion of a radio receiver.

Abstract: In the present invention, the conditions necessary for the change from the reducing-pressure mode to the holding pressure mode are changed based on the length of the period of instability from the beginning of wheel slippage to the stopping of this slippage, and the length of the period of continued severe locking in which the slip ratio of the wheel exceeds a certain fixed value. Therefore, even when there is a disturbance in the form of roughnesses in the road surface or the like, this is determined to be a temporary phenomenon and the switching of the setting from the reducing-pressure mode to the holding pressure mode can take place in a reliable manner, and the usual, stable braking power can be achieved in correspondence with the relationship between the road surface and the tires.