Search results
Results from the WOW.Com Content Network
Negative resistance oscillators are mainly used at high frequencies in the microwave range or above, since feedback oscillators function poorly at these frequencies. [11] [116] Microwave diodes are used in low- to medium-power oscillators for applications such as radar speed guns, and local oscillators for satellite receivers.
The negative-resistance oscillator model is not limited to one-port devices like diodes; feedback oscillator circuits with two-port amplifying devices such as transistors and tubes also have negative resistance. [15] [16] [11] [17] At high frequencies, three terminal devices such as transistors and FETs are also used in negative resistance ...
The negative resistance of the screen grid cancels the positive resistance of the tuned circuit, causing oscillations. As in the dynatron oscillator the control grid can be used to adjust the negative resistance. Since the transitron oscillator didn't depend on secondary emission it was far more reliable than the dynatron.
The negative differential resistance, combined with the timing properties of the intermediate layer, is responsible for the diode's largest use: in electronic oscillators at microwave frequencies and above. A microwave oscillator can be created simply by applying a DC voltage to bias the device into its negative resistance region. In effect ...
Hysteresis is due to the bulb's negative resistance, the fall in voltage with increasing current after breakdown, [7] [14] which is a property of all gas-discharge lamps. Up until the 1960s sawtooth oscillators were also built with thyratrons. [15] [16] These were gas-filled triode electron tubes. These worked somewhat similarly to neon bulbs ...
A "locally active resistor" is a device that has negative resistance and is active (it can amplify), providing the power to generate the oscillating current. The locally active resistor and nonlinearity are combined in the device N R, which is called "Chua's diode". This device is not sold commercially but is implemented in various ways by ...
In 1956 W. T. Read and Ralph L. Johnston of Bell Telephone Laboratories proposed that an avalanche diode that exhibited significant transit time delay might exhibit a negative resistance characteristic. The effect was soon demonstrated in ordinary silicon diodes and by the late 1960s oscillators at 340 GHz had been produced.
One method of oscillator analysis is to determine the input impedance of an input port neglecting any reactive components. If the impedance yields a negative resistance term, oscillation is possible. This method will be used here to determine conditions of oscillation and the frequency of oscillation. An ideal model is shown to the right.