Fairchild Semiconductor Corporation

Ethan A Crain

Etan Shacham

Pravas Pradhan

Karl Rapp

A low read current, low power consumption sense amplifier well suited for low frequency RFID systems is disclosed. An MOS transistor receives the read current from a memory cell, typically an EEPROM, and a current mirror is formed by a parallel MOS transistor. The mirror current is integrated on a capacitor after the charge on the capacitor is cleared via a reset pulse. A time period is defined during which the voltage on the capacitor is compared to a second voltage. The second voltage is formed from a reference voltage or from dummy cells, in either case the reference voltage is at about the logic boundary between a one and zero stored in a memory cell. A comparator, with or without input hysteresis, receives the voltage on the capacitor and a second voltage and within the time period, the output state of the comparator indicates the binary contents of the memory cell.

Current integrating sense amplifier for memory modules in RFID

A folder common cascode circuit with symmetric parallel signal paths from the differential inputs to the differential outputs provides a low skew, low jitter, low power differential amplifier. The signal paths on either side of the differential amplifier are made equal with equal loads along each path. Pairs of complementary NMOS and PMOS transistor pairs with parallel complementary biasing stacks on the output cascode circuitry maintain symmetrical parallel signal paths, amplification and impedance loading from differential input to differential output. Output voltage translating inverters provide a higher voltage level output signal while maintaining low skew and jitter.

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Cambridge, MA, United States of America

Ethan A Crain