Back to results
US 2004/0164890 A1Published application
Analog to digital converter selecting reference voltages in accordance with feedback from prior stages
AssigneeOki Electric Industry Co., Ltd.
InventorTakashi Konno
Life of this patent
Estimating the term…
Abstract
An A/D converter includes first to Nth stages of A/D conversion units, which are connected in series, each A/D conversion unit converting an analog input signal into a digital output signal. Each of the A/D conversion units includes a) a sample-and-hold circuit, which holds an analog input signal; b) a selector which selects one from a plurality of reference voltage signals in accordance with a digital output signal outputted from the one stage preceding A/D conversion unit; and c) a comparator which compares an output signal supplied from the sample-and-hold circuit with the reference voltage signal selected by the selector.
Claims24
An A/D converter comprising:
- first to Nth stages of A/D conversion units, which are connected in series, each A/D conversion unit converting an analog input signal into a digital output signal;
- each of the A/D conversion units comprises:
- a) a sample-and-hold circuit, which holds an analog input signal;
- b) a selector which selects one from a plurality of reference voltage signals in accordance with a digital output signal outputted from the one stage preceding A/D conversion unit;
- and
- c) a comparator which compares an output signal supplied from the sample-and-hold circuit with the reference voltage signal selected by the selector.
3 more elements
An A/D converter comprising:
- first to Nth stages of A/D conversion units, which are connected in series, each A/D conversion unit converting an analog input signal into a digital output signal in synchronization with a clock signal, wherein
- each of the A/D conversion units comprises:
- a) a sample-and-hold circuit, which holds an analog input signal;
- b) a selector which selects one from a plurality of reference voltage signals in accordance with a digital output signal outputted from the one stage preceding A/D conversion unit;
- and
- c) a comparator which compares an output signal supplied from the sample-and-hold circuit with the reference voltage signal selected by the selector to generate a digital output signal thereof, wherein,
- an output signal of the comparator for the one stage preceding A/D conversion unit is supplied to the selector therein,
- even-numbered stages of A/D conversion units and odd-numbered stages of A/D conversion units operate in synchronization with clock signals having the opposite phases,
- ith stage of A/D conversion unit further comprises (N−i+1) pieces of flip-flop circuits to which an output signal of the comparator in the one stage preceding A/D conversion unit is supplied, and
- in ith stage of A/D conversion unit, the selector selects one reference voltage signal from 2i-1 pieces of reference voltage signals.
7 more elements
An A/D converter comprising:
- first to Nth stages of A/D conversion units, which are connected in series, each A/D conversion unit converting an analog input signal into a digital output signal in synchronization with a clock signal, wherein
- the first stage of A/D conversion unit is a flash A/D conversion unit of m-bit flash type, where “m” is smaller than “N”, in which the flash A/D conversion unit comprises a m-bit flash A/D conversion circuit;
- a sample and hold circuit which holds an analog input signal;
- and m*(N−m) pieces of flip-flop circuits, in which each of serially connected (N−m) pieces of flip-flop circuits form a line so that “m”lines of (N−m) flip-flop circuits are connected in parallel to output terminals of the m-bit flash A/D conversion circuit,
- each of the second to Nth stages of A/D conversion units comprises:
- a) a sample-and-hold circuit, which holds an analog input signal;
- b) a selector which selects one from a plurality of reference voltage signals in accordance with a digital output signal outputted from the one stage preceding A/D conversion unit;
- and
- c) a comparator which compares an output signal supplied from the sample-and-hold circuit with the reference voltage signal selected by the selector to generate a digital output signal thereof, wherein,
- an output signal of the comparator for the one stage preceding A/D conversion unit is supplied to the selector therein,
- even-numbered stages of A/D conversion units and odd-numbered stages of A/D conversion units operate in synchronization with clock signals having the opposite phases,
- ith stage of A/D conversion unit further comprises (N−i+1) pieces of flip-flop circuits to which an output signal of the comparator in the one stage preceding A/D conversion unit is supplied, and
- in ith stage of A/D conversion unit, the selector selects one reference voltage signal from 2i-1 pieces of reference voltage signals.
10 more elements
Dependencies are inferred from the claim text.