Patent ID: 6087873
Filing Date: 2000-07-11
Classification: H03K

Abstract:
A hysteresis circuit for introducing a hysteresis voltage offset into a switched comparator circuit, the comparator circuit having first and second inputs to which input signals are applied and stored during a reset period and which are compared during a following comparison period by the comparator for providing output signals at first and second outputs thereof, the hysteresis circuit comprising:a current generating circuit for sourcing a hysteresis current at an output thereof;a circuit receiving said hysteresis current and having first and second inputs at which is applied a differential hysteresis voltage, the polarity of which depends on the comparator output signals produced during the previous comparison period such that said circuit produces a hysteresis voltage offset in response to said hysteresis current at a selected one of the first and second inputs of the switched comparator depending on the polarity of said differential hysteresis control voltage applied thereto during the current reset period; anda switch circuit for connecting said output of said current generating circuit to said circuit during said current reset period and disconnecting the same therefrom during said following comparison period wherein said hysteresis voltage offset is not canceled during said following comparison period but remains superimposed on the stored input signal applied at said selected input to influence the output of the switched comparator during said following current comparison period based on the output of the switched comparator resulting from said previous comparison period.