Millimeter wave switch

Abstract

A switch selectively provides one of a first input signal at a first frequency and a second input signal at a second frequency to an output terminal with low insertion loss and high isolation between the first and second input signals. The first input signal is received at a first input terminal and the second input signal is received at a second input terminal. A switching element electrically connects the first input terminal and the output terminal to provide the first input signal to the output terminal in a first state and isolates the first input terminal from the output terminal in a second state. A bias line is electrically connected to provide a control signal to the switching element to select between the first state and the second state. An AC coupled transmission line is electrically connected to the second input terminal and electrically connected between the switching element and the output terminal. The control signal is provided through the AC coupled transmission line when the switching element is in the first state to isolate the second input terminal from the output terminal and provide the first input signal to the output terminal. The second input signal is provided DC coupled to the output terminal through the AC coupled transmission line when the switching element is in the second state.

Description

BACKGROUND OF THE INVENTION [0001] Switches have long been used in electrical circuit designs to isolate a portion of an electrical circuit. In its simplest form, a switch operates to allow a signal to pass from an input terminal to an output terminal in a “closed” position and to prevent the signal from passing from the input terminal to the output terminal in an “open” position. [0002] In the microwave and mm-wave frequency range, switches are used in instrumentation, communications, radar, fiber optic and many other systems that require high-frequency switching. For example, a switch can be used for pulse modulation, port isolation, transfer switching, high-speed switching, replacement of mechanical parts and other switch applications. [0003] There a number of commercially available high-frequency switches on the market today. However, these switches have all failed to simultaneously obtain high switch isolation greater than 15 dBm, high power handling above 24 dBm and low insert...

AI Technical Summary

Benefits of technology

The present invention provides a switch that can selectively provide two input signals to an output terminal. The switch uses a series switching element and a shunt switching element connected to an AC coupled transmission line. The control signal is provided through the AC coupled transmission line when the series switching element is in the first state to isolate the second input terminal from the output terminal and provide the first input signal to the output terminal. The second input signal is provided DC coupled to the output terminal through the AC coupled transmission line when the series switching element is in the second state. The switch has improved power handling and low insertion loss and high isolation by placing the shunt switching elements as close as possible to the AC coupled transmission line and using two shunt switching elements on either side of the AC coupled transmission line. The invention also provides other features and advantages such as simplistic biasing scheme and improved isolation.

Problems solved by technology

However, these switches have all failed to simultaneously obtain high switch isolation greater than 15 dBm, high power handling above 24 dBm and low insertion loss of a fraction of a dB from DC to mm-wave frequencies.

For example, high-frequency switches employing field-effect transistors (FETs) typically are unable to handle high frequencies in the mm-wave range and / or high power above 24 dBm.

In the alternative, FET-based solutions may have high insertion loss.

In addition, waveguide-based switches are difficult to integrate and lack the required bandwidth coverage to DC.

Furthermore, coupling-based diplexers typically have poor isolation and high insertion loss at the cross-over frequency.

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