22-08-2013 дата публикации
Номер: US20130214760A1
A latch circuit that uses two interoperating latches. The latch circuit has the beneficial feature that it switches only a single time during a measurement that uses a stair step or ramp function as an input signal in an analog to digital converter. This feature minimizes the amount of power that is consumed in the latch and also minimizes the amount of high frequency noise that is generated by the latch. An application using a plurality of such latch circuits in a parallel decoding ADC for use in an image sensor is given as an example. 1. A minimal power latch circuit , comprising:{'b': 1', '0, 'a first latch and a second latch, said first latch having an input at which to receive a comparator signal C, an input at which to receive a code value signal D, and an input at which to receive a signal Q from said second latch, and having an output at which to provide an output signal Q; and'}{'b': 0', '1, 'said second latch having an input at which to receive said comparator signal C, an input at which to receive said code value signal D, and an input at which to receive said signal Q from said first latch, and having an output at which to provide said output signal Q;'}{'o': [{'@ostyle': 'single', 'b': '0', 'Q′'}, {'@ostyle': 'single', 'b': '0', 'Q'}, {'@ostyle': 'single', 'C'}, {'@ostyle': 'single', 'b': '0', 'Q'}], 'b': 1', '1', '1, 'said first latch and said second latch constructed to operate according to a pair of equations in which a first latch equation is given by =( \ue8a0D)+ +Q and a second latch equation is given by Q′=(Q+D)\ue8a0C\ue8a0 ;'}said comparator signal C representing a comparison as a function of time of a signal to be measured and a monotonically varying reference signal;said code value signal D representing a time increment measured from a start of said monotonically varying reference signal; and{'b': 0', '1, 'a selected one of said signal Q and said signal Q encoded with information indicative of said code value signal D at a time when no more ...
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