We present low-cost millimeter-wave (MMW) photonic techniques for implementing gigabit/s wireless links. A passive mode-locked laser consisting of a Fabry-Perot laser and a single-mode fiber is used to generate 120-GHz optical MMW signals. We modulated these MMW signals by controlling the bias voltage of the photodiode. The MMW generation and modulation methods do not need expensive photonic components or high-power drivers. A link employing these low-cost photonic techniques achieved 1.25-Gbit/s wireless data transmission.

A new low-power feedback structure for a power amplifier (PA) reduces signal distortion while keeping the power efficiency of the PA high. The feedback structure injects the envelope of the third-order harmonics into the input signal. In adopting this method for a class-A amplifier, we obtain over 10% higher efficiency while maintaining the same adjacent channel power ratio (ACPR). The power consumption of additional circuit is 200 µW.

To reduce power consumption of wireless terminals, we have developed ultra-low leakage regulator circuits that control the intermittent terminal operation with very small activity ratio. The regulator circuits supply about 100 mA in the active mode and cut the leakage current to a nanoampere level in the standby mode. The operation of the ultralow-leakage regulator circuits with CMOS/SOI and bulk technologies is described. The leakage-current reduction mechanism in a proposed power switch with bulk technology is explained. Measurement shows that the power switch using reversely biased bulk transistors has a leakage current that is almost as small as that of conventional CMOS/SOI transistor switches.

A fifth-order switched-capacitor (SC) complex filter was implemented in 0.2-µm CMOS technology. A novel SC integrator was developed to reduce the die size and current consumption of the filter. The filter is centered at 24.730.15 kHz (3δ) and has a bandwidth of 20.260.3 kHz (3δ). The image channel is attenuated by more than 42.6 dB. The in-band third-order harmonic input intercept point (IIP3) is 17.3 dBm, and the input referred RMS noise is 34.3 µVrms. The complex filter consumes 350 µA with a 2.0-V power supply. The die size is 0.578 mm2. Owing to the new SC integrator, the filter achieves a 27% reduction in die size without any degradation in its characteristics, including its noise performance, compared with the conventional equivalent.

A micro-power active-RFID LSI with an all-digital RF-transmitting scheme achieves experimental 10-m-distance communication with a 1-Mbps data rate in the 300-MHz frequency band. The IC consists of an RF transmitter and a power supply circuit. The RF transmitter generates wireless signals without a crystal. The power supply circuit controls the energy flow from the battery to the IC and offers intermittent operation of the RF transmitter. The IC draws 1.6 µA from a 3.4-V supply and is implemented in a 0.2-µm CMOS process in an area of 1 mm2. The estimated lifetime of the IC is over ten years with a coin-size battery.

Hot carrier reliability due to residual damage in the gate oxide created by synchrotron X-ray irradiation is investigated for subquarter-micrometer NMOSFETs under a wide irradiation-dose range (103,000 mJ/cm2). Although irradiation-induced interface-traps and positive charges are completely eliminated after 400 post-metalization-annealing, neutral electron traps partially remain. The effects of the residual trapa on hot-carrier degradation can be negligible when gate oxides thinner than about 5 nm are used, and it is found that there is no effect of irradiation damage on interface-trap generation due to injected hot-carriers. It is concluded that the influence of synchrotron radiation X-ray lithography on hot-carrier-induced degradation in subquarter-micrometer NMOSFETs can be negligible.

This paper reports L-band and C-band monolithic low noise amplifiers (LNA) fabricated with MOSFET/SIMOX (Separation by IMplanted OXygen) technology for the first time. The L-band LNA exhibits a Gain/(PdcNF) ratio of 0.7/mW, which demonstrate the potential performance advantage of this technology. The C-band LNA has 0.05/mW at 5.8 GHz. The L-band amplifier had a gain of 8.5 dB at 0.5 V, which is the lowest supply voltage ever reported in Si-based LNAs. These LNAs consist of 0.25-µm nMOSFET/SIMOX, spiral inductors, and capacitors which are fabricated with a conventional digital CMOS LSI process. It demonstrates that L- and C-band RF circuits can be made on a SIMOX wafer together with large-scale digital circuits.

The design and performance of a sub-nanoampere two-stage power management circuit that uses off-chip capacitors for energy accumulation are presented. Focusing on the leakage current and the transition time of the power switch transistor, we estimated the minimum current for accumulating. On the basis of the results, we devised a two-stage power management architecture for sub-nanoampere operation. The simulated and experimental results for the power management circuit describe the accumulating operation with a 1-nA current source.

To reduce the power dissipation of the receiver in accordance with the intensity of the received signal, we developed the first intra-symbol intermittent (ISI) radio-frequency (RF) front end with 0.35-µm CMOS technology. In the demodulation mechanism, the RF output of the low-noise amplifier (LNA) is down-converted to an intermediate frequency (IF) by the mixer, and the LNA and mixer operate synchronously and intermittently within the length of a single symbol. Because the time-averaged power consumption is proportional to the operating time, the demodulation can be performed with low power by making the total operating time short. We experimentally demonstrate that demodulation (BPSK: 9.6 kbps) is properly achieved with the operating-time ratio of 12%. This ISI operation of the RF front end is enabled by a newly devised fast-transition LNA and mixer. A theoretical analysis of aliasing noise reveals that RF ISI operation is more useful than current-control with continuous operation and that an operating-time ratio of 10% is optimal.

A low-voltage 6-GHz-band monolithic LC-tank VCO has been fabricated using 0.2-µm CMOS/SIMOX process technology. The VCO features a tuning-range switching technique to achieve a wide tuning range. The output frequency range is between 5.71 and 6.21 GHz owing to the tuning-range switch. With the tuning-range switch on or off, the phase noise is about -100 dBc/Hz at 1-MHz offset and about -120 dBc/Hz at 10-MHz offset frequency at the supply voltage of 2 V.

Wireless data transmission at 3.0 Gbit/s was achieved by using millimeter-wave photonic techniques, such as optical 120-GHz subcarrier generation, optical modulation, and high-power photonic millimeter-wave emission. We have successfully demonstrated the transmission of optical Gigabit Ethernet signals over this link.