Cubic has been granted a patent for a digital phase shifter that can be used in Monolithic Microwave Integrated Circuits (MMIC) and hybrid digital phase shifters. The phase shifter includes input and output ports, with multiple transmission lines arranged in a ring. The transmission lines are divided into two pairs, each arranged in a series path. One of the transmission lines in each pair is a quarter-wave hybrid coupled line. This design allows for low loss, wide bandwidth, and high linearity. GlobalData’s report on Cubic gives a 360-degree view of the company including its patenting strategy. Buy the report here.
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Digital phase shifter with quarter-wave hybrid coupled line
A recently granted patent (Publication Number: US11689189B2) describes a digital phase shifter that can be used to manipulate the phase of signals. The phase shifter includes an input port for receiving signals and an output port for transmitting phase-shifted signals. It also consists of a series of transmission lines arranged in a ring configuration.
In one embodiment, the transmission lines are quarter-wave hybrid coupled lines, which are electrically connected to terminations at opposing ends. These terminations can be configured as shunt inductors or shunt capacitors, allowing for different phase states. The selected transmission line can be a 3-dB hybrid coupled line or a Lange coupler, which includes an RF crossover.
The Lange coupler in the phase shifter comprises coupled-ports and through-ports terminated in short-circuits. These short-circuits reflect signals through the transmission line with a natural 180-degree phase shift at different frequencies, creating a phase inversion. The selected transmission line combines the signals reflected by the short-circuits to create a 270-degree phase shift, with 90 degrees coming from the quarter-wave length and 180 degrees from the natural phase shift.
Another embodiment of the digital phase shifter includes four metal strips arranged in parallel, with a first pair electrically connected to ground by an airbridge structure and a second pair connected to ground by another airbridge structure. This configuration allows for precise control of the phase shifting process.
The phase shifter can also include a pair of FETs (Field-Effect Transistors) that steer signals in different directions around the ring between the input and output ports. Each FET is connected to an inductor that resonates the capacitance of the FET, enhancing the performance of the phase shifter.
In summary, the granted patent describes a digital phase shifter with various configurations and components that enable precise control over the phase of signals. The phase shifter can be used in various applications where phase manipulation is required, such as in communication systems and signal processing.