The overall linearizer model has been implemented in a system simulator (working with complex signals), also allowing the investigation of second-order distortion effects (not taken into account during the dimensioning of the structure). The power amplifier to be linearized is described by nonlinear functions experimentally derivable from large signal S-parameters the mathematical model is based on the complex power series expansion of these functions and on the definition of a suitable scaling rule illustrated in this paper. A mathematical model for the linearizer is described, which allows an optimum choice of the various design parameters (taking into account several constraints due to the specific implementation environment). This solution is explored for application to weakly nonlinear receiver amplifiers and easy-to-use relationships are presented to enable designers to assess the frequency limits of the technique for particular devices and processes.Ī linearizer architecture, based on predistortion and well suited for monolithic-microwave integrated-circuit (MMIC) implementation is presented in this paper. A possible solution to this problem, that has recently been advocated, relies on a process termed 'augmentation'. Consequently a method of amplifier linearisation is required that has minimal impact on the power consumption, size and noise figure of the receiver system. In military aircraft, where weight and space are at a premium, these effects are difficult to accommodate. Conventional methods that are used to improve linearity, such as increasing device size, bias current or supply voltage, inevitably result in enhanced thermal noise, higher power consumption and heat dissipation. The extremely wide dynamic range of the target returns in such systems leads to challenging receiver design compromises between amplifiers exhibiting low distortion or low thermal noise.

In airborne military phased array radar systems, detection capability is influenced as much by receiver linearity as it is by system noise performance.

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