Solid state radio-measuring optical-frequency transducer of gas flow rate

Abstract

The paper presents a study of a solid state radio-measuring optical-frequency transducer of gas consumption based on a transistor structure with a negative differential resistance. A mathematical model of a solid state radio-measuring optical-frequency flowmeter was developed, which made it possible to obtain the conversion function and the sensitivity equation. The solid state radio-measuring optical-frequency gas flowmeter is based on a transistor structure with a negative differential resistance, consisting of a HEMT field-effect transistor and a bipolar transistor with a passive inductive element. When replacing the passive inductance with an active inductive element, the transducer can be completely integrated. The operation of a solid state radio-measuring optical-frequency gas flowmeter is based on the interferometric method of refractometry of optically transparent liquids and gases. The negative differential resistance formed by the parallel connection of the impedance with the capacitive component on the collector-drain electrodes of the transistor structure and inductance leads to the occurrence of electrical oscillations in the oscillator circuit. Theoretical and experimental studies have shown that with an increase in gas consumption 0 l/h to 4 l/h, the generation frequency decreases 812.65 MHz to 811.62 MHz at a supply voltage of 3.3 V, and at a supply voltage of 3.8 V 813.00 MHz to 811.80 MHz. It is shown that by choosing a constant voltage power supply mode, it is possible toobtain an almost linear dependence of the generation frequency on the gas flow rate and choose channels for transmitting measurement information. Studies have shown that the sensitivity of the developed device is 262kHz/l/h. The obtained theoretical and experimental studies are in good agreement, the relative error does not exceed 2.5%.