Devices and methods for a detection system and heterodyne mixer having a local oscillator (LO) input, a radio frequency (RF) input, an intermediate frequency (IF) output, and a suspended waveguide structure that has a quartz substrate and patterned metal transmission line with a plurality of suppression slots.

Devices and methods for a detection system and heterodyne mixer having a local oscillator (LO) input, a radio frequency (RF) input, an intermediate frequency (IF) output, and a suspended waveguide structure that has a quartz substrate and patterned metal transmission line with a plurality of suppression slots.

A FET based double balanced mixer (DBM) that exhibits good conversion gain and IIP3 values and provides improved linearity and wide bandwidth. In one embodiment, a first balun is configured to receive a local oscillator (LO) signal and generate two balanced LO signals that are coupled to two corresponding opposing nodes of a four-node FET ring. A second balun is configured to pass an RF signal on the unbalanced side. The FET ring includes at least four FETs connected as branches of a ring, with the source of each FET connected to the drain of a next FET in the ring. Each FET is preferably fabricated as, or configured as, a low threshold voltage device having its gate connected to its drain, which causes the FET to operate as a diode, but with the unique characteristic of having close to a zero turn-on voltage.

A FET based double balanced mixer (DBM) that exhibits good conversion gain and IIP3 values and provides improved linearity and wide bandwidth. In one embodiment, a first balun is configured to receive a local oscillator (LO) signal and generate two balanced LO signals that are coupled to two corresponding opposing nodes of a four-node FET ring. A second balun is configured to pass an RF signal on the unbalanced side. The FET ring includes at least four FETs connected as branches of a ring, with the source of each FET connected to the drain of a next FET in the ring. Each FET is preferably fabricated as, or configured as, a low threshold voltage device having its gate connected to its drain, which causes the FET to operate as a diode, but with the unique characteristic of having close to a zero turn-on voltage.

A first phase shift circuit (2) converts impedance to achieve impedance matching between a third terminal (1c) of a 90-degree hybrid circuit (1) and a first terminal (4a) of a first nonlinear element (4), and shifts a phase of a radio wave by 180 degrees, and a second phase shift circuit (3) converts impedance to achieve impedance matching between a fourth terminal (1d) of the 90-degree hybrid circuit (1) and a first terminal (5a) of a second nonlinear element (5), and shifts a phase of a radio wave by 90 degrees. As a result of this configuration, a conversion loss of radio waves can be reduced.

A first phase shift circuit (2) converts impedance to achieve impedance matching between a third terminal (1c) of a 90-degree hybrid circuit (1) and a first terminal (4a) of a first nonlinear element (4), and shifts a phase of a radio wave by 180 degrees, and a second phase shift circuit (3) converts impedance to achieve impedance matching between a fourth terminal (1d) of the 90-degree hybrid circuit (1) and a first terminal (5a) of a second nonlinear element (5), and shifts a phase of a radio wave by 90 degrees. As a result of this configuration, a conversion loss of radio waves can be reduced.

An apparatus includes a first circuit and a second circuit. The first circuit may have a first diode and a second diode connected as anti-parallel diodes and physically adjacent to each other in a substrate. The second circuit may have a third diode and a fourth diode connected as anti-parallel diodes and physically adjacent to each other in the substrate. The first circuit and the second circuit may be configured to mix two input signals to generate an output signal. A polarity of every other physically neighboring diode may be reversed.

The invention discloses a passive wideband mixer, including a local oscillator balun, a radio frequency balun, a first diode D1, a second diode D2, a third diode D3, a fourth diode D4, an inductive compensation unit, and a lossy inductive grounding network. The invention can realize a mixer with a bandwidth ratio of not less than 1:7, and can effectively suppress points with isolation deterioration without affecting the conversion loss over the entire frequency band. In the entire frequency band of this design, the isolation indicator between the local oscillator and radio frequency ports is optimized, which can well satisfy the application of the wideband mixer in a communication system.

The invention discloses a passive wideband mixer, including a local oscillator balun, a radio frequency balun, a first diode D1, a second diode D2, a third diode D3, a fourth diode D4, an inductive compensation unit, and a lossy inductive grounding network. The invention can realize a mixer with a bandwidth ratio of not less than 1:7, and can effectively suppress points with isolation deterioration without affecting the conversion loss over the entire frequency band. In the entire frequency band of this design, the isolation indicator between the local oscillator and radio frequency ports is optimized, which can well satisfy the application of the wideband mixer in a communication system.

A microstrip mixer of a microwave-doppler detecting module has a shared port, a local oscillator signal input port and a mixing output port and includes two mixer tubes. The local oscillator signal input port is electrically connected with the shared port and is electrically connected with an end of one of the mixer tubes through the shared port. The local oscillator signal input port is also electrically connected with the mixing output port and is electrically connected with an end of the other mixer tube through the mixing output port. The other ends of the two mixer tubes are respectively grounded. Accordingly, the microstrip mixer is configured to have an open structure having three ports, which is more flexible and enhances the applicability thereof while reducing the size of the microwave-doppler detecting module utilizing the microstrip mixer.