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SummaryA systematic method to design high power and high efficiency mm‐wave fundamental oscillators is presented. By using a linear time variant method, we first obtain the optimum conditions and show that these conditions can be significantly different for high power and high efficiency fundamental oscillation. Next, we propose a modified multistage ring oscillator with interstage passive networks to exploit the full capacity of the transistors in terms of output power or efficiency. Analytical expressions are also derived to determine the value of passive elements used in the oscillator. To verify the validity of the method, a 77‐GHz two‐stage (differential) VCO is designed in a 65‐nm CMOS process. Careful electromagnetic and circuit simulations demonstrate that the designed VCO has 2‐GHz tuning range, maximum output power of 10.5 dBm and maximum DC to RF efficiency of 24.1%. The designed VCO shows 54.8% and 108.7% improvement in terms of maximum output power and efficiency compared with a conventional cross‐coupled VCO with the same tuning range.

A new ultra wideband (UWB) pulse shape is proposed to mitigate coexistence issues of IEEE802.11.a WLAN and impulse radio UWB (IR-UWB) systems. The proposed method is applicable to the reduction of mutual interference of UWB and any given narrowband (NB) systems. This pulse shape is based on frequency up-converting of the first derivative of the Gaussian pulse which has an adjustable null in power spectral density (PSD) depending on the up-converting frequency. Analytical and simulation results show that both UWB and WLAN systems have noticeable improved performance when using the proposed pulse in comparison with using conventional modulated Gaussian (MG) pulse in UWB system. The new pulse does not reduce the throughput of the UWB system and does not require modification of the NB system. The proposed transmitter circuit block diagram has been presented at the conclusion.