Belgians push linear in CMOS

Belgians push linear in CMOS
Steve Bush Belgian researchers have developed a switched capacitor (SC) op amp which operates at only 0.9V. The development promises to extend the suitability of SC techniques for future low voltage CMOS processes, interfacing external analogue signals to on-chip digital circuitry, for instance. “Switched capacitor [SC] analogue building blocks, used in filters and data converters, are robust and high quality circuits which can be integrated alongside digital circuits using standard CMOS processes,” said Vinceno Peluso, one of the researchers at the University of Leuven: “But thinner gate oxides of future deep-submicron CMOS will not withstand the supply voltages required for their satisfactory operation.” The crux is the series-type analogue switches used in conventional SC designs which need a relatively high supply voltage to operate correctly. Parallel switches (which short the signal path to 0V or Vcc) need less supply voltage, but cannot be used because suitable SC architectures require the outputs of the circuit op amps to be shorted. This can result in damage, high operating current or poor performance. The Leuven op amp is isolated from its local power when its output is shorted, removing the problems associated with parallel switching. So far the amplifier, which has been tested on 0.7?m CMOS, has been used to fabricate a 12-bit 3.3kHz bandwidth sigma-delta A/D converter operating at 1.5V and consuming 100?W.


Leave a Reply

Your email address will not be published. Required fields are marked *

*