Patent ID: 7902894

Claim:
An accurate hysteretic comparator (HYSCP) for comparing an input signal voltage VIN A with an input signal voltage VIN B and producing a 2-level output signal VOT reflecting the relative magnitude between VIN A and VIN B with a hysteresis window V hys , the HYSCP comprises: a differential input stage with current output (DICO) having a number of differentially connected input transistors with transistor transconductance Gm tnx for converting said VIN A and VIN B , with an input stage transconductance Gm in , into corresponding IIN A and IIN B ; a steerable offset current generator (SOCG), controlled by a logic steering control signal, for generating and steering an offset current IOS through either one of its two output offset currents IOS A or IOS B ; and a current-to-voltage summing converter (IVSC) connected to the IIN A , IOS A , IIN B and IOS B for: respectively summing the currents (IIN A , IOS A ) and the currents (IIN B , IOS B ) and converting the summed currents into the 2-level output signal VOT plus the steering control signal having its logic states corresponding to the VOT levels thus causing V hys =IOS/Gm in ; and wherein the input transistors are connected to form negative feedback loops, such that the transistor transconductance Gm tnx are largely negated from the input stage transconductance Gm in and wherein the DICO further comprises a feedback resistance R NF connected to the input transistors such that Gm in becomes dominated by and essentially equal to the feedback conductance G NF =1/R NF independent of the Gm tnx whose large variation over transistor fabrication process and device operating environment would otherwise cause a corresponding inaccuracy of the V hys .