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Spectrum measurement results of a CMOS ring oscillator are presented that show a 10 dB decrease in l/f noise induced phase noise at a 2 dB increase in carrier power. Simple ring oscillator theory predicts that the l/f noise induced phase noilse is independent of carrier power. It is shown that an increase in the amplitude of oscillation is accompanied by a reduction of the intrinsic l/f noise of the periodically switched MOS transistors in the ring. A net reduction of the l/f noise of a periodically switched NMOS transistor of more than 12 dB is measured in baseband.Recently we found that the effect has been observed before in a weaker form with an alternative experimental setup [4]. However, to our knowledge, we are the first to explore the impact of the effect in a practical application.The results presented here are relevant for the study of the l/f noise induced phase noise in CMOS oscillators. The contribution of l/f noise to the phase noise in CMOS oscillator topologies can be lowered significantly by increasing the amplitude of oscillation as this can result in a reduction of the intrinsic l/f noise of MOS transistors in baseband.

In this work we present a new device: the boost transistor. The boost transistor is an LDMOS transistor that is controlled by a separate field plate boost electrode that reduces the specific on-resistance R on A. By applying a positive voltage V boost , this electrode creates an accumulation layer in the drain extension of the device. Compared to the single gate device, the boost transistor results in a specific on-resistance R on A reduction of 15% without requiring any process modification, as is demonstrated by measurements and TCAD simulations. The on-state efficiency with respect to standard LDMOS designs is enhanced and a driving circuit is proposed mantaining the breakdown voltage at 70 V.