RF Phase Shifter is an RF component that is used to change the phase angle of the transmission input signal. RF phase shifter will shift the phase of the signal without varying the amplitude to the input signal, after considering the insertion loss of the component.
A phase shift module provides a controllable phase shift to the signal passing through it and it is primarily used in phased arrays in Radar systems.
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To understand the RF phase shifter in detail, we recommend you to understand the following RF components.
In this RF and microwave phase shifter article, we will cover,
Phase shifting is an electronic device that shifts the phase of the signal by adding a very small amount of delay to the input signal and then mixing it back with the original signal (By doing so, the certain signal frequencies are in or out of phase with each other). The phase shift value is directly proportional to the amount of time delay to the signal. There are basically 2 types of phase shifters are available, on the base of components used in the design: Active and Passive phase shifter.
Passive phase shifters are made of passive components and have a higher loss in the signal during the phase shifting. The passive phase shifter will have applications in Radar passive electronically scanned array systems.
In an Active phase shifter, the phase shifter amplifies circuits are used for the phase shifting. These phase shifters offer gain in the circuits and will have good noise figure values. These phase shifters are used for the applications like an active electronically scanned array for Radar systems. The feedback amplifier network offers phase shifts by 180 or 360 degrees at the output of the loop.
RF and Microwave phase shifters are basically are of the fixed phase shifter and of variable phase shifter types. In a fixed phase shifter the output signal from it will have a fixed value of phase variation and for the variable phase shifter, any phase value can be set in the phase variation range by a control circuit.
RF variable phase shifters are digital, analog and mechanical based on the shifting mechanism of the phase shifter.
Analog Phase shifters are made of analog control circuits and the phase variation is controlled by external voltage levels. The phase shift of the analog phase shifter will be based on the tuning voltage levels specified for each value. Analog phase shifters are easy to implement and offer stable output phase signals.
In a digital phase shifter, the phase of the signal is shifted by a digitally controlled circuit via a computer or processor interface. Currently, digital phase shifters are available with a USB phase interface, which enables the control from a computer easily. Digital phase shifters are quick in response and able to set the precise phase shifting values.
In Mechanical Phase Shifter the device phase is manually controlled with a knob on the phase shifter. These turning a knob will adjust the phase of the output signal by a specified value. The accuracy of the mechanically tuned phase shifter will be lesser than an analog or digital phase shifter.
RF Phase Shifter is used for many applications in the RF and Microwave systems like phase array antenna in RADAR systems, steerable radio communications link etc.
Analog and digital phase shifters operating in the RF and microwave, or millimetre wave frequency range are used for the below variety of industrial applications.
For the RF phase shifter, the value of the phase variation without the variation in the amplitude is the prime factor need to consider in the selection process. In addition, when selecting an RF and microwave phase shifter it is ideal to check the below listed key parameters for confirming the suitability of the selected component for the design application.
The frequency range of the phase-shifter indicates the range of frequency over which the phase shifter will perform the required phase shifting.
Type indicates the fixed or the variable phase shifting. For the variable type requirement, the control type like digital, analog or mechanical tuning needs to select as per the application. Another parameter that needs to consider is the phase tuning step size of the controller.
The phase Range of the phase shift indicates the range of degrees on which phase shifter can provide a phase shift. Another parameter that needs to consider for the variable phase shifter is the phase resolution.
Output signal flatness indicates the variation of the output signal power level after the phase shifting. The lower value for the flatness indicates better the operation.
Phase accuracy of the RF phase shifter indicates the correctness of the phase variation of the signal to the set value.
Settling time for the variable phase shifter indicate the time required to set to a new phase value once the phase change control signal is applied. Faster the setting time of the phase shifter, the better for the application.
Insertion loss of the phase shifter indicates the loss of the signal when it passes through the phase shifter to the output. It is expressed in dB and for the Ideal RF phase shifter, the insertion loss value will be zero. However, all the devices will have a slight loss, the lower the loss the better the device performance.
The Voltage Standing Wave Ratio of the phase shifter indicates the amount of the energy reflected when the signal is fed into the phase shifter. Lower the VSWR, better the performance of the system.
Input Power of phase shifter indicates the maximum RF power level in Watts can be applied to the input port of the device without damage to it by excessive heating. For the ideal applications, the peak and the average power handling of the device need to consider.
RF phase shifters are available in different packages like SMD modules, Through-hole technology modules, Connectorized devices and Waveguide assemblies. SMD and Through-hole technology modules are suitable for the board level design of the RF systems. The conveyorized and waveguides are suitable for high power system-level applications.
For the analog phase shifter, the phase control voltage interface will be a solder pin and for the digital phase shifter, now it is available with a USB interface.
The phase shifter is one of the prime useful components in the RF and Microwave test and control requirements. A fixed phase shifter will provide a fixed phase shift to the output signal without varying the amplitude of the input signal. For the variable phase shifter, the output signal phase can be set by using external analog, digital or mechanical circuits within the phase shift range.
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