Masafumi Kondou

A 0.3mm 2 90-to-770MHz fractional-N Synthesizer for a digital TV tuner

This paper describes a 0.3mm2 and a 90M-to-770MHz range low spurious fractional-N synthesizer, with which mobile receivers for Japanese terrestrial digital broadcasting are equipped. The synthesizer for DTV tuner needs to cover 90Mto–108MHz which is scheduled for ISDB-Tsb, and 170M-to-222MHz which is scheduled for ISDB-Tmm etc, and 470M-to-770MHz for ISDB-T. And the synthesizer needs a frequency resolution of 1/7MHz to receive each segment. In addition, it is demanded that the synthesizer minimize the macro area to reduce costs while maintaining other performance (phase noise, power consumption, tracking time, etc.) from a previous work [1].

A PVT Tolerant PLL with On-Chip Loop-Transfer-Function Calibration Circuit

A PVT tolerant PLL architecture which uses two on-chip digital calibration circuits to maintain loop transfer function is presented. Test chips with 9 conditions, MOSes, resistors and capacitors, were fabricated in a 90 nm CMOS technology. Experimental results show that the phase noise remains + 2dBc/Hz within 10 MHz offset under any PVT condition.

A 60 mV-3 V input range boost converter with amplitude-regulated and intermittently operating oscillator for energy harvesting

This paper presents an oscillator-assisted boost converter that can extend the input-voltage range of a conventional boost converter and expand its application opportunities in energy harvesting systems. The input range is enlarged by using a transformer-based oscillator that can provide a sufficient amount of voltage to drive a switched inductor boost converter at ultra-low input voltages. Moreover, the oscillator uses an amplitude regulation circuit (ARC) rather than high power-consuming protective devices to suppress the expansion of the oscillation amplitude at high input voltages, which can avoid overvoltage problems without sacrificing the power efficiency. Additionally, a power-down circuit (PDC) that is controlled by an internal negative voltage is implemented to turn off the oscillator when the boost converter can be driven by its own output. Thus, power consumption by the oscillator can be eliminated and the power efficiency can be improved. The experimental results showed that the proposed circuit enabled an input range from 60 mV to 3 V. To the best of our knowledge, this is the first time that a boost converter supporting a wide input range from sub-100 mV to several volts has been achieved. Furthermore, we also achieved an overall efficiency of more than 42% and a peak efficiency of 93% over this wide input range.