Patent ID: 7911237
Filing Date: 2011-03-22
Classification: H03K

Abstract:
1. A comparator, comprising: a differential amplifier having differential inputs forming comparator inputs, and a first and a second amplifier output forming comparator outputs of a first comparator stage, wherein the differential amplifier has first and second parallel branches; a first current source circuit, defining a current to be driven through the differential amplifier; a second current source circuit, comprising a load driven by the first branch; a third current source circuit, comprising a load driven by the second branch; and circuitry for defining the voltage difference between the first and second amplifier outputs when the differential amplifier is in a stable state providing a differential output comprising a first holding transistor between the second amplifier output and the second current source, and a second holding transistor between the first amplifier output and the third current source, wherein the holding transistors hold the voltage difference between the amplifier outputs at their threshold voltage and the first branch comprising a first drive transistor in series with a first switching transistor, the second amplifier output being defined at the junction between the first drive transistor and the first switching transistor, the second branch comprising a second drive transistor in series with a second switching transistor, the first amplifier output being defined at the junction between the second drive transistor and the second switching transistor.