Power Detection and Control For Mobile Handset Applications - Part 3. Power Control Feedback

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  • Author: David Ripley
Direct detection architectures can sample the amplifier output directly but will suffer from similar VSWR inaccuracy that was observed in the indirect architectures. Often a directional coupler is required to sample the RF waveform and provide visibility to the forward power delivered to the load. This coupler can be integrated on the detector die, implemented with discrete components or embedded with the printed circuit board. Figure 1 shows an example embedded coupler used in low cost amplifier modules. Along with the coupler, a complex termination is often required to optimize the coupler
directivity over a narrow bandwidth.