A linear capacitor structure using fractal geometries is described. This capacitor exploits both lateral and vertical electric fields to increase the capacitance per unit area. Compared to standard parallel-plate capacitors, the parasitic bottomplate capacitance is reduced. Unlike conventional metal-to-metal capacitors, the capacitance density increases with technology scaling. A classic fractal structure is implemented with 0.6-m metal spacing, and a factor of 2.3 increase in the capacitance per unit area is observed. It is shown that capacitance boost factors in excess of ten may be possible as technology continues to scale. A computer-aided-design tool to automatically generate and analyze custom fractal layouts has been developed.

Abstract-This paper presents a 115-mW Global Positioning System radio receiver that is implemented in a 0.5-m CMOS technology. The receiver includes the complete analog signal path, comprising a low-noise amplifier, I-Q mixers, on-chip active filters, and 1-bit analog-digital converters. In addition, it includes a low-power phase-locked loop that synthesizes the first local oscillator. The receiver achieves a 2.8-dB noise figure (prelimiter), a 56-dB spurious-free dynamic range, and a 17-dB signal-to-noise ratio for a noncoherent digital back-end implementation when detecting a signal power of 0130 dBm at the radio-frequency input.

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A phase-locked-loop (PLL)-based frequency synthesizer incorporating a phase detector that operates on a windowing technique eliminates the need for a frequency divider. This new loop architecture is applied to generate the 1.573-GHz local oscillator (LO) for a Global Positioning System receiver. The LO circuits in the locked mode consume only 36 mW of the total 115-mW receiver power, as a result of the power saved by eliminating the divider. The PLL's loop bandwidth is measured to be 6 MHz, with a reference spurious level of 047 dBc. The front-end receiver, including the synthesizer, is fabricated in a 0.5-m, triple-metal, single-poly CMOS process and operates on a 2.5-V supply.

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