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  • 1
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    Basic formulas find oscillator power gain (1990)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: Traditional circuit analysis defines the power gain of an oscillator to be finite, since there is an output without an input. By defining power gain as the ratio of output power to input power, however, finite power gain can be characterized. Several simple circuit equations which can be used to find power gain in an oscillator circuit are presented and discussed.
    Keywords: ELECTRONICS AND ELECTRICAL ENGINEERING
    Type: Microwaves & RF (ISSN 0745-2993); 29; 127-129
    Format: text
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    NASA TECHNICAL REPORTS
  • 2
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    Programmable electronic synthesized capacitance (1987)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A predetermined and variable synthesized capacitance which may be incorporated into the resonant portion of an electronic oscillator for the purpose of tuning the oscillator comprises a programmable operational amplifier circuit. The operational amplifier circuit has its output connected to its inverting input, in a follower configuration, by a network which is low impedance at the operational frequency of the circuit. The output of the operational amplifier is also connected to the noninverting input by a capacitor. The noninverting input appears as a synthesized capacitance which may be varied with a variation in gain-bandwidth product of the operational amplifier circuit. The gain-bandwidth product may, in turn, be varied with a variation in input set current with a digital to analog converter whose output is varied with a command word. The output impedance of the circuit may also be varied by the output set current. This circuit may provide very small ranges in oscillator frequency with relatively large control voltages unaffected by noise.
    Keywords: ELECTRONICS AND ELECTRICAL ENGINEERING
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    NASA TECHNICAL REPORTS
  • 3
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    Low phase noise oscillator using two parallel connected amplifiers (1987)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A high frequency oscillator is provided by connecting two amplifier circuits in parallel where each amplifier circuit provides the other amplifier circuit with the conditions necessary for oscillation. The inherent noise present in both amplifier circuits causes the quiescent current, and in turn, the generated frequency, to change. The changes in quiescent current cause the transconductance and the load impedance of each amplifier circuit to vary, and this in turn results in opposing changes in the input susceptance of each amplifier circuit. Because the changes in input susceptance oppose each other, the changes in quiescent current also oppose each other. The net result is that frequency stability is enhanced.
    Keywords: ELECTRONICS AND ELECTRICAL ENGINEERING
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    NASA TECHNICAL REPORTS
  • 4
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    Reflection oscillators employing series resonant crystals' (1989)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A reflection oscillator is provided which employs an active device operated in its roll-off region and two resonant circuits. For an oscillator employing a bipolar transistor, the emitter is connected to a series resonant capacitor-crystal network and the base is connected to an L-C tank circuit with the transistor being operated in the roll-off region of its gain versus frequency curve. This will provide a very high frequency of operation with a relatively inexpensive, low frequency, active device. These oscillators are easily tuned, stable, and require little dc power.
    Keywords: ELECTRONICS AND ELECTRICAL ENGINEERING
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    NASA TECHNICAL REPORTS
  • 5
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    High input impedance amplifier (1995)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: High input impedance amplifiers are provided which reduce the input impedance solely to a capacitive reactance, or, in a somewhat more complex design, provide an extremely high essentially infinite, capacitive reactance. In one embodiment, where the input impedance is reduced in essence, to solely a capacitive reactance, an operational amplifier in a follower configuration is driven at its non-inverting input and a resistor with a predetermined magnitude is connected between the inverting and non-inverting inputs. A second embodiment eliminates the capacitance from the input by adding a second stage to the first embodiment. The second stage is a second operational amplifier in a non-inverting gain-stage configuration where the output of the first follower stage drives the non-inverting input of the second stage and the output of the second stage is fed back to the non-inverting input of the first stage through a capacitor of a predetermined magnitude. These amplifiers, while generally useful, are very useful as sensor buffer amplifiers that may eliminate significant sources of error.
    Keywords: ELECTRONICS AND ELECTRICAL ENGINEERING
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  • 6
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    Temperature responsive transmitter (1987)
    In:  CASI
    Details
    Publication Date: 2019-08-28
    Description: A temperature responsive transmitter is provided in which frequency varies linearly with temperature. The transmitter includes two identically biased transistors connected in parallel. A capacitor, which reflects into the common bases to generate negative resistance effectively in parallel with the capacitor, is connected to the common emitters. A crystal is effectively in parallel with the capacitor and the negative resistance. Oscillations occur if the magnitude of the absolute value of the negative resistance is less than the positive resistive impedance of the capacitor and the inductance of the crystal. The crystal has a large linear temperature coefficient and a resonant frequency which is substantially less than the gain-bandwidth product of the transistors to ensure that the crystal primarily determines the frequency of oscillation. A high-Q tank circuit having an inductor and a capacitor is connected to the common collectors to increase the collector current flow which in turn enhances the radiation of the oscillator frequency by the inductor.
    Keywords: Electronics and Electrical Engineering
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    NASA TECHNICAL REPORTS
  • 7
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    Crystal oscillators using negative voltage gain, single pole response amplifiers (1989)
    In:  CASI
    Details
    Publication Date: 2019-08-28
    Description: A simple and inexpensive crystal oscillator is provided which employs negative voltage gain, single pole response amplifiers. The amplifiers may include such configurations as gate inverters, operational amplifiers and conventional bipolar transistor amplifiers, all of which operate at a frequency which is on the roll-off portion of their gain versus frequency curve. Several amplifier feedback circuit variations are employed to set desired bias levels and to allow the oscillator to operate at the crystal's fundamental frequency or at an overtone of the fundamental frequency. The oscillator is made less expensive than comparable oscillators by employing relatively low frequency amplifiers and operating them at roll-off, at frequencies beyond which they are customarily used. Simplicity is provided because operation at roll-off eliminates components ordinarily required in similar circuits to provide sufficient phase-shift in the feedback circuitry for oscillation to occur.
    Keywords: Electronics and Electrical Engineering
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  • 8
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    Wideband, High-Input-Impedance Buffer Amplifier (1996)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: Improved buffer amplifier offers high input impedance to signal source. Input impedance remains high, relatively constant, and essentially resistive over wide range of frequencies.
    Keywords: ELECTRONIC COMPONENTS AND CIRCUITS
    Type: GSC-13571 , NASA Tech Briefs (ISSN 0145-319X); 20; 4; P. 38
    Format: text
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    NASA TECHNICAL REPORTS
  • 9
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    Crystal Oscillators Operate Beyond Rated Frequencies (1990)
    In:  Other Sources
    Details
    Publication Date: 2019-07-12
    Description: Amplifiers with single-pole frequency responses used in their "roll-off" regions. Class of crystal oscillators based on use of negative-voltage-gain amplifiers at frequencies well into "roll-off" frequency regions of their gain-versus-frequency curves. Defining characteristic helps keep costs of oscillators low; not necessary to use more expensive amplifiers that have flat frequency responses out to desired operating frequencies. Enables amplifier to produce phase shift necessary for oscillation, reducing cost further by eliminating need for some of passive components in oscillators of more conventional design.
    Keywords: ELECTRONIC COMPONENTS AND CIRCUITS
    Type: GSC-13171 , NASA Tech Briefs (ISSN 0145-319X); 14; 4; P. 30
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  • 10
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    Reflection Oscillators Containing Series-Resonant Crystals (1989)
    In:  Other Sources
    Details
    Publication Date: 2019-07-12
    Description: Crystal-controlled transistor reflection oscillator easily tunable and stable, consumes little power, and costs less than other types of oscillators operating at same frequencies. Made possible by design concept that includes operation of transistor well beyond 3-dB frequency of current-versus-frequency curve. Concept takes advantage of newly available crystals resonating at frequencies up to about 1 GHz. Useful in determining approximate frequency of oscillation and major elements determining frequency.
    Keywords: ELECTRONIC COMPONENTS AND CIRCUITS
    Type: GSC-13173 , NASA Tech Briefs (ISSN 0145-319X); 13; 8; P. 20
    Format: text
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