Abstract: A miniaturised half-wave balun comprises a single-ended I/O port comprising a first signal carrying terminal for connection to a source impedance and a differential I/O port comprising second and third signal carrying terminals for connection to a load impedance. First and second transmission line sections of equal length and characteristic impedance are connected together at a common end and at opposite ends to the second and third terminals. The first signal carrying terminal is coupled to the first transmission line section. The combined length of the first and second transmission line sections is substantially less than one half of the wavelength of an RF signal at the operating frequency. First and second loading shunt capacitors are connected to respective first and second transmission line sections. A shunt capacitive element is connected at the common end of the transmission line sections.

Abstract: A compact RF differential circuit has a first differential I/O port comprising a first pair of signal carrying terminals which is connected to a source termination and a second differential I/O port comprising a second pair of signal carrying terminals which is connected to a load termination. The common mode impedance measured at either the first or second differential I/O port is zero. The differential mode impedance measured at the first differential I/O port is equal to the differential mode impedance of the source termination, and the differential mode impedance measured at the second differential I/O port of the circuit is equal to the differential mode impedance of the load termination.

Abstract: A compact RF differential circuit has a first differential I/O port comprising a first pair of signal carrying terminals which is connected to a source termination and a second differential I/O port comprising a second pair of signal carrying terminals which is connected to a load termination. The common mode impedance measured at either the first or second differential I/O port is zero. The differential mode impedance measured at the first differential I/O port is equal to the differential mode impedance of the source termination, and the differential mode impedance measured at the second differential I/O port of the circuit is equal to the differential mode impedance of the load termination.

Abstract: A miniaturised half-wave balun comprises a single-ended I/O port comprising a first signal carrying terminal for connection to a source impedance and a differential I/O port comprising second and third signal carrying terminals for connection to a load impedance. First and second transmission line sections of equal length and characteristic impedance are connected together at a common end and at opposite ends to the second and third terminals. The first signal carrying terminal is coupled to the first transmission line section. The combined length of the first and second transmission line sections is substantially less than one half of the wavelength of an RF signal at the operating frequency. First and second loading shunt capacitors are connected to respective first and second transmission line sections. A shunt capacitive element is connected at the common end of the transmission line sections.

Abstract: A component for a simulation tool, the component comprising means for defining a model of a circuit element, for example an inductor, capacitor or resistor. The defining means comprises a set of performance parameters, for example S-parameters, that define the performance of the circuit element over a range of frequencies. The parameter set is derived from the performance of the circuit element in a test environment, for example on a test substrate. The defining means further includes means for negating the effect on the parameter set of the test environment. The negating means is conveniently derived from a circuit model having a circuit topology derived from a circuit model of the test environment, but in which component values are negated in comparison with the corresponding component values of the test environment model.