IN Brief:
- ATT A-Series attenuators cover DC to 20GHz with standard attenuation values from 0dB to 20dB.
- The 2.03×1.65×0.30mm devices use thin-film resistors on a ceramic substrate with 50Ω matched RF connections.
- Power handling reaches 6.5W CW at 100°C, with operation specified from -55°C to +125°C.
Knowles has introduced its ATT A-Series fixed attenuators for RF and microwave signal chains operating from DC to 20GHz. The surface-mount family combines precision thin-film resistors on a ceramic substrate with a 2.03×1.65×0.30mm package intended for densely populated assemblies where designers need controlled attenuation without adding a large discrete RF component.
Standard attenuation values run from 0dB to 20dB, with 50Ω matched RF inputs and outputs. Knowles also offers customised attenuation values, power ratings, and configurations where the standard range does not suit the application. Continuous-wave power handling reaches 6.5W at 100°C, while the specified operating temperature range extends from -55°C to +125°C.
An attenuator performs a simple function at system level: it reduces signal amplitude by a defined amount. Achieving that consistently over a 20GHz frequency span is less straightforward. The component has to maintain its intended attenuation while controlling reflections and avoiding excessive variation as frequency, temperature, and operating conditions change.
The 50Ω interfaces are intended to maintain compatibility with the characteristic impedance used throughout most RF test and communications hardware. A mismatch at the attenuator can return part of the signal towards the source, altering the behaviour of neighbouring components and making the nominal attenuation value a poor description of what the complete signal path experiences.
Knowles uses a thin-film resistive structure on ceramic to provide the attenuation network. Thin-film processing gives manufacturers close control over resistor geometry and value, while the ceramic substrate provides a stable mechanical and thermal base. For the system designer, the important result is repeatability across devices and operating conditions rather than the fabrication method in isolation.
The company identifies radar, electronically steered arrays, electronic support measures, transmit and receive modules, wireless infrastructure, satellite communications, and RF test equipment among the applications. Fixed attenuation can be used in those systems to align channel amplitudes, protect a sensitive receiver stage, improve return loss, control dynamic range, or set the signal level entering an amplifier, mixer, or measurement instrument.
Multi-channel equipment makes component consistency particularly important. Phased-array systems can contain large numbers of parallel RF paths whose amplitude and phase behaviour have to remain sufficiently close for calibration to work. Variation in a nominally identical passive component can therefore become a system-level error when it is repeated across many channels.
The 6.5W rating also addresses the thermal side of the design. An attenuator turns part of the RF power applied to it into heat, so power capability depends on how effectively that heat can leave the ceramic body and enter the PCB or surrounding assembly. The headline rating is specified at 100°C; actual usable power will depend on board construction, thermal environment, airflow, duty cycle, and the attenuation value selected.
Knowles specifies operation down to -55°C and up to +125°C, supporting equipment exposed to wider environmental conditions than ordinary laboratory RF hardware. That does not by itself qualify the part for every aerospace, defence, or automotive programme, where vibration, materials, lifetime, screening, and formal qualification requirements may also apply, but it gives designers a defined temperature envelope for initial component selection.
The A-Series is pin compatible with established industry-standard chip attenuator footprints, according to Knowles. That can reduce the amount of PCB redesign needed when an existing product requires greater bandwidth, different power handling, or an alternative source. Pin compatibility still requires the surrounding layout to be checked at the intended frequency, particularly towards 20GHz where pad geometry, transmission-line dimensions, and discontinuities become increasingly significant.
The launch therefore addresses an incremental but persistent RF design constraint. Signal chains are carrying wider bandwidths while assemblies are becoming denser, leaving less room for bulky conditioning components. A fixed attenuator that covers DC to 20GHz in a familiar surface-mount footprint allows signal-level control to remain a relatively compact part of the design rather than forcing another mechanical compromise into the RF path.
