Broadband Linearisers (BLIN) Broadband Linearisers for High Capacity Ka-Band Multibeam Payloads

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The funded activity focuses on the development of KA-band MMICs enabling a fully electronic tuning of the LCAMP nonlinearity to the TWT nonlinearity. The viability of the approach is to be shown on three different levels of integration: On lowest level an extensive RF characterization of the MMICs is to be performed. On the second level the new MMICs have to be tested in conjunction with heritage MMICs. For final validation a hardware demonstrator of the nonlinear LCAMP section comprising the developed MMICs and heritage building blocks is to be tuned to a representative variety of TWT data.


The main challenges can be seen in finding a circuit topology providing enough tuning range for gain, phase, gain slope and phase slope. In the ideal case the aforementioned quantities should have minimum interference in order to allow for an easy tuning procedure. Another challenge is to keep the circuit as simple as possible in order to respect restrictions in terms of maximum chip area and insertion loss. Finally operation must be possible with GHz bandwidth.


In the current generation of equipment the tuning procedure to a dedicated TWT involves changes of the hardware e.g. by setting or removal of bond wires. The new chipset enables in orbit predistortion adjustment, but also automation of the up to now manual tuning procedure on ground. In the manufacturing process manual interventions on the hardware are eliminated and manual tuning can be replaced by automatic tuning, which is expected to considerably save time. 


The first type of developed equalizers allows for a broadband control of the gain, phase, gain slope and phase slope of the differential equalizer residing within the linearizer. The second type, which is outside the linearizer, provides a tunable gain slope to compensate inclined frequency responses.

System Architecture

Within the project a demonstrator for the nonlinear LCAMP section is designed, built and characterized using the newly developed MMICs. It comprises all nonlinear elements of the LCAMP such as the linearizer and the limiting amplifier and small signal amplifiers.


The first main step of this project is the survey of the existing literature which results in the design concept of the project and in the preliminary design review. After this first milestone the main focus is switched to the accurate design of the Non Linear Section (NLS). The final NLS design is reviewed in the design readiness review. After procurement, manufacturing and testing of the NLS a test result review is conducted to confirm specified performance. A Final review concludes this activity.

Current status

All project activities, such as literature survey, design, manufacturing and testing, have been completed successfully.

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