Remarks: The data compiled are the basic parameters when the product is selected. The specific working principle is not described in detail. Please refer to the relevant bibliography. PIN diode switch The microwave switch uses the PIN tube to exhibit impedance characteristics of approximately on and off under direct current and reverse bias, and realizes the function of controlling the conversion of the microwave signal channel. The DC volt-ampere characteristics of a PIN diode are the same as those of a PN junction diode, but there is an essential difference in the microwave band. Since the total charge of the PIN diode I layer is mainly generated by the bias current, rather than by the instantaneous value of the microwave current, it exhibits only one linear resistance to the microwave signal. This resistance value is determined by the DC offset. The resistance value is small when the positive bias is biased, close to the short circuit, and the resistance value is large when the reverse bias is applied, which is close to the open circuit. Therefore, the PIN diode does not produce a non-linear rectifying effect on the microwave signal, which is an essential difference from a general diode, and is therefore suitable for use in a microwave control device. Main parameter description Insertion loss and isolation The PIN tube actually has a certain value of reactance and loss resistance. Therefore, the switch is not zero when it is turned on, and becomes a positive insertion loss. When the switch is turned off, its attenuation is not infinite, and it becomes isolation. When measuring the main indicators of the switch, it is generally expected that the insertion loss is small and the isolation is large. Switching time Due to the storage effect of the charge, the PIN tube transitions from the off state to the on state, and from the on state to the off state, a process is required, and the time required for this process becomes the switching time. The "on delay" is the time required to control the pulse by 90% to 10% of the controlled microwave pulse envelope; “Switch on time†is the time required for the controlled microwave pulse envelope to range from 10% to 90%, and also becomes the “rising edgeâ€; The "shutdown delay" is the time required to control the pulse from 10% to 90% of the controlled microwave pulse envelope; The "switch off time" is the time required for the controlled microwave pulse envelope to range from 90% to 10%, which also becomes the "falling edge". The general "on delay" and "off delay" depend on the driver circuit, while the "rising edge" and "falling edge" depend on the choice of PIN tube and bias circuit. Withstand power The maximum input power that a microwave switch can withstand under given operating conditions. It is related to the PIN tube power capacity, circuit type (series or parallel), and operating state (CW and pulse) for heat dissipation conditions. There are two general damage mechanisms: voltage breakdown, which is common in pulse power, and thermal burnout, which is common in CW. Voltage standing wave coefficient The voltage standing wave coefficient only reflects the port input and output matching. The port voltage VSWR is the smallest, and the loss of the switch is not necessarily the smallest; but the switch with the smallest loss has a small voltage standing wave coefficient. harmonic PIN diodes are non-linear and therefore generate harmonics. When applied to a wide range of applications, harmonics may fall into the band and cannot be filtered out, so care should be taken. Structure description Reflection and absorption switches: The reflective switch is isolated by reflecting the input microwave signal when the PIN diode is turned on. Therefore, the standing wave relationship is good in the "on" state, and the standing wave is poor in the "off" state; The switch uses the reflected signal when the load absorbs the PIN diode to turn on, which improves the port standing wave, so the standing wave in the "on" and "off" states is better. In general, reflective switches are more powerful than absorption switches, but at a lower price. The absorption switch reduces the interstage traction of the system in the off state. Titanium Sunglasses,Eyewear Titanium,Titanium Frame Sunglasses,Sunglasses With Titanium Frames Danyang Hengshi Optical Glasses Co., Ltd. , https://www.hengshi-optical.com
Description of switching parameters of microwave radio frequency