A 90-nm MOS-only 3-11GHz transmitter for UWB

This paper presents an upconversion mixer that uses triode devices and dynamic biasing to achieve smooth current steering and very low spur levels, e.g. at 3 times the local oscillator frequency. This eliminates the need for filtering resulting in a low-cost design free of inductors and external filters. The mixer is sized to provide all the required power to the antenna without requiring a separate power amplifier. Eliminating the RF amplification results in a very large RF bandwidth (3-11 GHz) again without any need for inductors for bandwidth extension. The transmitter has been fabricated in a 90nm digital CMOS process and achieves a peak power of 3dBm, while dissipating 36mW from a 1.2V supply. The transmitter supports a baseband bandwidth in excess of 1GHz. This performance is compatible with OFDM-based UWB requirements.