Abstract: A multiplexer, such as a diplexer, is delineated. The multiplexer may be employed in a communications system that may communicate in multiple frequency bands within a predefined range of frequencies, e.g., 2400 MHz-4900 MHz. The communications system may operate in a network, such as a wireless local area network, without significant interference from signals used by a cellular/mobile telephone system. The multiplexer may include multiple channels with bandpass filters that may be formed with lumped inductors and lumped capacitors. In at least one of the channels, the bandpass filter may be formed by combining at least one lowpass filter with at least one highpass filter.

Abstract: A multiplexer, such as a diplexer, is delineated. The multiplexer may be employed in a communications system that may communicate in multiple frequency bands within a predefined range of frequencies, e.g., 2400 MHz-4900 MHz. The communications system may operate in a network, such as a wireless local area network, without significant interference from signals used by a cellular/mobile telephone system. The multiplexer may include multiple channels with bandpass filters that may be formed with lumped inductors and lumped capacitors. In at least one of the channels, the bandpass filter may be formed by combining at least one lowpass filter with at least one highpass filter.

Abstract: A laminated lowpass filter (100) is disclosed. The filter (100) has: a stack of dielectric substrates (301-312) having a ground via (118); a pi network coupled between an input (202) and an output (202'); a first leg comprising a first transmission line (608) and a first capacitance (C1) connected to a top ground plane (GP1); a second leg comprising a second transmission line (608') and a second capacitance (C2) connected to a bottom ground plane (GP2); a middle leg including a transmission line (606) is between the first and second leg; the single point ground plane configuration prevents ground loops and minimizes the passage of stray signals through the laminated lowpass filter (100).

Abstract: A narrow-band overcoupled directional coupler 300 in a multilayer package is provided. The directional coupler 300 has a laminated structure including a stack of dielectric substrates (301-310) with a primary and a secondary transmission line on the layers of the dielectric substrates. The primary transmission line (A) and the secondary transmission line (B) are coupled by a combination of edge type coupling in which the primary and secondary transmission lines are substantially parallel with each other on a major surface of one of the dielectric substrates (307 for example) and broadside type coupled in which at least portions of the primary transmission line and secondary transmission line are substantially vertically aligned through adjacent dielectric substrates (303, 305 for example). The primary and secondary transmission lines are also substantially overcoupled to provide a predetermined off-center frequency which is different from an overcoupled center frequency.