New leakage-compensation technique for superior current-to-frequency conversion (10 super(-15) A to 10 super(-8) A)

We present a new technique to be used with ultra-low-level current-to-frequency converters (CFC) to enlarge their dynamic range of measurement (by a factor of ten). This technique also enables one to realize a more sensitive (by a factor of ten) CFC (I sub(min) = 10 super(-15) A) than all previously realized one (I sub(min) = 10 super(14) A). This technique is based on the carrier-heating phenomenon in short-channel MOSFETs. Our experimental work showed that this technique permits efficient compensation of CFC leakage current. Additional circuitry may be introduced to provide automatic leakage-current compensation.