Patent ID: 7009861
Filing Date: 2006-03-07
Classification: G11C

Abstract:
1. A Content Addressable Memory (CAM) cell providing improved speed and enhanced reliability, comprising: a data latch with complementary data terminals, a pair of complementary data lines that provide data connectivity with the data latch during read, write and search operations, a pair of input controlled switches that selectively couple the data latch terminals to the complementary data lines during read or write operations, a pair of output series pass transistors, each having its control terminal connected to a separate terminal of the data latch, one of its main terminals connected to a separate bit line, and the second main terminal connected to the corresponding terminal of the other series pass transistor, a Match Output signal line that identifies a match/no-match at the end of a Search operation, an output controlled switch having its control terminal connected to the common main terminal of the series pass transistors, while one of its main terminals drives the Match Output signal line to provide the result of the search operation, and a Search Enable signal line that enables the output controlled switch only during the search operation, the arrangement being such that during the search operation neither of the output series pass transistors conducts if the complementary bit line data matches the data latch outputs, one of the output series pass transistors conducts maximally providing a minimal voltage drop and a low impedance charging path for the bootstrap capacitance at the enabled output controlled switch when the complementary bit line data does not match the latch data, and one of the series pass transistors conducts to discharge the bootstrap capacitance at the beginning of the precharge period of the complementary bit lines.