Signal processing devices such as phase shifting devices are known.
Such signal processing devices typically receive a signal to be processed by the signal processing device and provide a signal processed by the signal processing device. The signal processing typically changes the received signal in some way to make it suitable for onwards transmission. Such signal processing devices may be used in telecommunications systems and may be required to operate at high frequencies. For example, signal processing devices such as phase shifters are required to process signals operating in the gigahertz region.
The choice of phase shifter for a particular application is influenced by many factors; for example, the amount of phase shift obtainable from the device, the insertion losses caused by the device and the power handling capability of the device. For lower power handling capabilities, the variation in phase shift is obtained by using a varactor and pin diode arrangement to achieve a variation of insertion phase. Although such phase shifters provide acceptable performance for low power operations, they have their shortfalls and these shortfalls are compounded in a typical telecommunications system where each radio frequency system usually requires a great number of such phase shifters.
Accordingly, it is desired to provide an improved phase shifting device.