Abstract: A non-linear active device (32), such as a FET, multiplies multiplicand signals to generate a product signal. A combining circuit (24) combines multiplicand signals into a combined signal. An input matching and conditioning network (28) couples the combined signal to an input of the active device (32). This network (28) matches impedances between sources for the multiplicand signals and the active device (32) at the frequencies of the multiplicand signals, and desirably shorts the product signal's frequencies. A feedback resistor (36) couples between the output and input of the active device (32) to lower impedance at the output and to stabilize the active device (32). An output matching and conditioning network (40) couples a mixed signal from the output of the active device to an output circuit (42). This network (40) matches impedances between the output circuit (42) and the active device (32) at the frequencies of the product signal, and desirably shorts the multiplicand signals' frequencies.

Abstract: A method for providing local matching elements for adjusting the characteristic impedance of local transmission line segments to more closely match the input or output impedance of the particular devices to which they couple. The method includes the step of providing a conductive bridge over the active lead of the transmission line, thereby lowering its characteristic impedance. The method can be applied to narrow transmission line segments needed to make contact to small active devices and/or MMIC's and which otherwise exhibit a substantial impedance mismatch with the small elements.

Abstract: The performance of microwave coplanar and other circuit boards is improved by providing local matching elements for adjusting the characteristic impedance of local transmission line segments to better match the input or output impedance of the particular devices to which they couple. This is accomplished by providing a conductive bridge over the active lead of the transmission line, thereby lowering its characteristic impedance. This is very useful for narrow transmission line segments needed to make contact to small active device and/or MMIC's and which otherwise exhibit a substantial impedance mismatch with such small elements.

Abstract: A broadband high frequency active MMIC circulator which includes low parasitic devices (MESFETs or HEMTs) and shunt feedback for impedance contouring in conjunction with a cascode/cascade isolation/gain network. To achieve circulation, a common series feedback node is required for each active element. While conventional active circulator topologies require the use of a resistive element for operation with a deleterious effect on noise performance, this broadband high frequency active MMIC circulator functions with either resistive or reactive common series feedback. When reactive feedback is selected, major improvements in noise performance can be realized.

Abstract: A distributed amplifier which increases gain by increasing transconductance comprises a plurality of amplifying elements. Each element includes a darlington amplifier connected in cascade with a FET (field effect transistor) amplifier. The darlington amplifier includes an RC (resistance/capacitance) feedback loop from the drain to the gate. Each of the amplifying elements are coupled in parallel between an input transmission line and an output transmission line. The output transmission line operates as a recombining network as the input signals pass through the amplifying elements. To further increase gain and power output, a time delay line is coupled to each end of the output transmission line. The time delay line simulates the terminating elements normally associated with distributed amplifiers, and collects unguided signals from the output transmission line to recombine them with guided signals at the output.

Abstract: Inductorless bias networks include a bias circuit having a bias return path which is coupled to and biases a variable impedance device in a relatively nonconductive state. Another bias circuit including a FET renders the variable impedance device relatively conductive in response to control signals so that one port is coupled to another port, for instance.