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A CMOS fully integrated 12th-order bandpass filter for low interemdiate frequency Bluetooth receivers is presented. The design is optimized to meet the selectivity and dynamic range requirements of Bluetooth while consuming relatively low power. The filter is based on unity gain cells and utilizes linearized MOSFET resistors for tuning. It exhibits a bandwidth of 1 MHz and a programmable center frequency range of 2 to 4 MHz. Experimental results obtained from a standard 0.5-[micro]m CMOS chip show that the filter exhibits an in-band dynamic range of 53.3 dB at gain of 0 dB, and 52 dB at gain of 15 dB, while consuming a total current of 1.32 mA. Attenuations of more than 10, 38, and 55 dB, are achieved for blockers one, two, and three, respectively. Index Terms--Bluetooth (BT) receivers, CMOS analog integrated circuits (ICs), current mode circuits, intermediate-frequency (IF) bandpass filters.

This paper presents a spurious-free switching buck converter with enhanced light-load efficiency for use in noise-sensitive portable electronics. The proposed switching buck converter achieves low output noise by using a delta-sigma-modulator (\Delta \Sigma) controller. Its light-load efficiency is enhanced by: 1) scaling the switching frequency of the buck converter (i.e., the sampling frequency of its \Delta \Sigma-modulator controller) with the load current; 2) switching its operation from continuous conduction mode (CCM) to discontinuous conduction mode (DCM) at light loads; and 3) using a new low-power current-sensing circuit. The \Delta \Sigma modulator is designed with an input-feedforward architecture, which enables the switching frequency of the controller to be scaled without disturbing the stability of the feedback loop of the buck converter, and also reduces the controller quiescent current. The proposed switching buck converter was fabricated in 0.13-\mum digital CMOS. Measurements results demonstrate that this buck converter achieves a spurious-free output with a noise floor below -60 dBm and voltage ripples below 70 mV over its full loading range (2 mA to 800 mA). Furthermore, it achieves a power efficiency higher than 70% over this entire range, with a peak efficiency of 95.1%. [ABSTRACT FROM PUBLISHER]