Various embodiments of the invention relate to attenuators with reduced temperature variation. By coordinating first-order resistance temperature (FORT) coefficients of resistors, embodiments of attenuator or attenuator cells are capable of achieving desired attenuation with reduced or minimized temperature variation. Such achievements in reducing temperature variation may be obtained without relying on resistors with large negative FORT coefficients. Attenuator cells may be configured as T-type attenuator cells, π-type attenuator cells, bridged-T attenuator cells, or shunt attenuators with various FORT coefficient combinations for the resistors incorporated within the attenuator cells. Furthermore, various attenuator cells may be cascaded together into a digital step attenuator with the temperature variation of those cells compensating or offsetting each other for an overall minimum temperature variation.

Various embodiments of the invention relate to attenuators with reduced temperature variation. By coordinating first-order resistance temperature (FORT) coefficients of resistors, embodiments of attenuator or attenuator cells are capable of achieving desired attenuation with reduced or minimized temperature variation. Such achievements in reducing temperature variation may be obtained without relying on resistors with large negative FORT coefficients. Attenuator cells may be configured as T-type attenuator cells, π-type attenuator cells, bridged-T attenuator cells, or shunt attenuators with various FORT coefficient combinations for the resistors incorporated within the attenuator cells. Furthermore, various attenuator cells may be cascaded together into a digital step attenuator with the temperature variation of those cells compensating or offsetting each other for an overall minimum temperature variation.

Digital step attenuator (DSA) and digital phase shifter (DPS) multi-stage circuit architectures that provide for high resolution. Embodiments use a dithering approach to weight bit positions to provide a much finer resolution than the lowest-valued individual stage. Bit position weights for stages are determined so as to enable selection of combinations of n bit positions that provide a desired total attenuation or phase shift range while allowing utilization of the large number of states (2.sup.n) available to produce fractional intermediate steps of attenuation or phase shift. The fractional intermediate steps have a resolution finer than the lowest-valued stage. Bit position weights may be determined using a weighting function, including weightings determined from a linear series, a geometric series, a harmonic series, or alternating variants of such series. In some embodiments, at least one bit position has a fixed value that is not determined by the bit position weighting function.

A radio frequency switch is disclosed. The RF switch uses a combination of transistor technology and a topology to create an RF switch that has a high isolation and a high voltage breakdown at frequencies including those above a gigahertz.

A modulation device includes a substrate, a metal layer, at least one driving element, and a modulation unit. The metal layer is disposed on the substrate and has at least one hole. The at least one driving element is disposed on the substrate and overlapped with the at least one hole. The modulation unit is electrically connected to the at least one driving element.

A digital step attenuator for automatic gain control in a transceiver front-end. The digital step attenuator includes a series path coupled between an input port and an output port, a plurality of series shunt switches coupled in parallel to the series path, and a plurality of parallel paths coupled to the series path in parallel. The series path includes a plurality of series resistors coupled in series. Each series shunt switch is for by-passing a different set of one or more series resistors. Each parallel path includes a parallel resistor and a parallel shunt switch, and each parallel path is coupled to either the input port, the output port, or an internal node between two adjacent series resistors, in parallel. A plurality of different -attenuators with a different topology are formed by selectively controlling the series shunt switches and the parallel shunt switches.

A first switch is connected in parallel with a circuit element. A second switch is connected in series with a parallel circuit constituted by the circuit element and the first switch. The first switch and the second switch alternately perform on-off operation.

A variable gain circuit includes: input/output terminals P1 and P2 configured to input/output a high frequency signal; a transistor having a signal terminal a connected to the input/output terminal P1, a signal terminal b connected to the input/output terminal P2, and a control terminal; bias terminals B1, B2 and B3, and a reference voltage terminal respectively set to a first variable voltage, a second variable voltage, a third variable voltage, and a fixed voltage that are independent of one another; an impedance element connected between the bias terminal B1 and the signal terminal a; an impedance element connected between the bias terminal B2 and the signal terminal b; an impedance element connected between the bias terminal B3 and the control terminal; and a first switch configured to switch between connecting and not connecting the reference voltage terminal and the control terminal.

A radio frequency switch is disclosed. The RF switch uses a combination of transistor technology and a topology to create an RF switch that has a high isolation and a high voltage breakdown at frequencies including those above a gigahertz.

A front end module includes: a first antenna terminal; a second antenna terminal; a switch including a plurality of first side terminals on a first side and a plurality of second side terminals on a side opposite to the first side, each of the first side terminals being connected to one of the first antenna terminal and the second antenna terminal; a first filter connected to the first antenna terminal; a second filter connected to the first antenna terminal; a third filter connected to one of the second side terminals; and a fourth filter connected to one of the second side terminals. The third filter and the fourth filter are connected to one of the first antenna terminal and the second antenna terminal.