Despite decades of research in developing "singlechip" radio transceivers, most commercial designs continue to rely on off-chip components for RF bandpass filtering. Implementing these filters on-chip remains nearly as challenging today as it was ten years ago due to problems in meeting system requirements. Recent advances in silicon-on-insulator IC processes targeted at RF designs, however, offer the possibility of producing commercially-viable on-chip filters in the coming years using Q-enhancement techniques. This paper reviews filter implementation alternatives and dynamic range (DR) requirements, illustrating the fundamental advantages of Q-enhanced LC filters over active, inductorless, Gm-C designs. A 900-MHz Q-enhanced filter with a 20-MHz bandwidth is reported that achieves 78-dB DR in a 1-MHz bandwidth while consuming 39 mW. While still 15-to 20-dB below performance of comparable-power amplifiers and mixers, investigations of noise figure and inductor Q illustrate how future designs can correct this deficiency, bringing DR performance into the commercially acceptable range.

An inherent shortcoming of rectifiers designed using standard CMOS devices is poor low input power performance. It is shown that this can be overcome through the use of intrinsic devices with close to zero-threshold voltage available in a 0.25 silicon-on-sapphire (SOS) CMOS process. A novel complementary bridge rectifier structure based on a combination of cross-connected and diode bridge rectifier topologies is introduced to avoid the excessive leakage current incurred through the use of intrinsic devices. A design strategy which maximizes efficiency and produces an input impedance which will interface well with the inductive coil type antennas used in biomedical implants is presented for this new rectifier type. The fabricated rectifier achieves a 1 DC output power for an input power of 26.5 dBm at 100 MHz. A peak measured power conversion efficiency of 67% is achieved at 100 MHz, but more importantly 30%is attained for a wide output power range which reaches as low as 40 dBm. At the target 1 output power a of 44% was achieved.Index Terms-AC-DC power conversion, CMOS integrated circuits, power conversion efficiency (PCE), power harvesting, radio frequency rectifier, wireless power transmission.

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A UHF RFID rectifier which turns on at near zero input voltage is demonstrated. The rectifier is fabricated in 0.25-μm silicon-on-sapphire (SOS) CMOS technology using intrinsic, near zero threshold devices. A novel improved cross-coupled bridge topology is used to minimize the leakage incurred through the use of intrinsic devices while maintaining their low power turn on characteristics. The fabricated rectifier demonstrates a peak power conversion efficiency (PCE) of 71.5% at 915MHz with a RF input of -4 dBm and a 30 kΩ load. More importantly, a PCE > 30% was measured for all RF input powers between -28 and -4 dBm demonstrating state-of-the-art efficiency across a wide range of input powers.Index Terms -AC-DC power conversion, CMOS integrated circuits, power conversion efficiency (PCE), radio frequency rectifier, RFID, ultra-high frequency (UHF), wireless power transmission.

In this letter, a fully integrated 20-dBm RF power amplifier (PA) is presented using 0.25-m-gate silicon-on-sapphire metal-oxide-semiconductor field-effect transistors (MOSFETs). To overcome the low breakdown voltage limit of MOSFETs, a stacked FET structure is employed, where transistors are connected in series so that each output voltage swing is added in phase. By using triple-stacked FETs, the optimum load impedance for a 20-dBm PA increases to 50 , which is nine times higher than that of parallel FET topology for the same output power. Measurement of a single-stage linear PA shows small-signal gain of 17.1 dB and saturated output power of 21.0 dBm with power added efficiency (PAE) of 44.0% at 1.88 GHz. With an IS-95 code division multiple access modulated signal, the PA shows an average output power of 16.3 dBm and PAE of 18.7% with adjacent channel power ratio below 42 dBc. Index Terms-Metal-oxide-semiconductor field-effect transistor (MOSFET), power amplifier (PA), silicon-on-sapphire (SOS), stacked transistors.