Pulse phase difference encoding circuit

An apparatus for producing an indication indicative of a time difference between first and second indicia, said apparatus comprising:

• a recirculating delay line, receiving said first indicia, formed of multiple delay elements connected together such that a delay element at a second end is connected to a delay element at a first end;
• a counter, connected to said recirculating delay line, counting a number of times that said first indicia recirculates between said delay element at said second end and said delay element at said first end;
• an encoder, coupled to receive outputs from each of said elements of said recirculating delay line and encoding a position of said first indicia within said outputs into a binary representation;
• and
• a latch, receiving said second indicia, latching said binary representation from said encoder and an output indicative of contents of said counter, when said second indicia occurs;
• wherein said encoder forms least significant bits of a digital word indicative of said time difference, and said counter forms most significant bits of said digital word indicative of said time difference.

An apparatus for producing an indication of a time difference between two pulses, said apparatus comprising:

• delay means, adapted to receive a first pulse, for delaying said first pulse in increments between its input and its output, said output of said delay means being connected to said input of said delay means to recirculate the first pulse, and for generating an increment output indicative of an increment status of said delay means, said increment output having a plurality of possible states each of which represents a different increment of said delay line;
• counting means for counting a number of times said delay means recirculates said first pulse;
• and
• receiving means, adapted to receive a second pulse, for producing an output indicative of both a count of said counting means and said delay means increment output, at a time of receiving said second pulse,
• wherein said counting means includes first and second counters counting a number of times said delay means recirculates said first pulse through first and second parts of said delay means, respectively, said first and second parts being different from one another.

An apparatus for determining a time difference between first and second pulses, said apparatus comprising:

• a delay line, receiving the first pulse as an input thereof, and delaying said first pulse by increments from a beginning of the delay line toward one end of the delay line, including a recirculating portion connecting one portion of the delay line to another portion of the delay line, and generating an output indicative of an increment of said delay line, said output having a plurality of possible states each of which represents a different increment of said delay line;
• and
• means, coupled to said recirculating portion, for producing a low resolution output, having a lower resolution than a resolution between said increments, at a time when said second pulse is received;
• and
• a latch, latching the delay line output and the low resolution output upon receipt of the second pulse.

A method of determining a time difference between first and second pulses, comprising the steps of:

• incrementally delaying the first pulse a number of times as it passes downstream toward a first delayed portion;
• connecting the first delayed portion to a second delayed portion, upstream of the first delayed portion;
• counting a number of times that said first pulse recirculates between the first delayed portion and second delayed portion using a digital count;
• detecting when said second pulse occurs and using, at that time, a count of the number of times as a low resolution measure of said time difference;
• determining a position in the first through second delayed portions as a high resolution measure of said time difference;
• latching said low resolution measure;
• combining said latched low resolution measure and said high resolution measure to provide an overall time difference;
• and
• adjusting a number of bits of output by changing a number of bits used in the counting step to change a dynamic range of the method.

A method of determining a time difference between first and second pulses, said method comprising the steps of:

• incrementally delaying the first pulse a number of times as it passes downstream toward a first delayed portion;
• connecting the first delayed portion to a second delayed portion, upstream of the first delayed portion;
• counting a number of times that said first pulse recirculates between the first delayed portion and the second delayed portion using a digital count;
• detecting when said second pulse occurs and using, at that time, a count of the number of times as a low resolution measure of said time difference;
• determining a position in the first through second delayed portions as a digital high resolution measure of said time difference;
• latching said low resolution measure;
• combining said latched low resolution measure and said high resolution measure to provide an overall time difference;
• and
• adjusting a number of bits of output by changing a number of bits in the counting step to change a dynamic range of the system.

A system for measuring a timing of an input signal applied thereto, said system comprising:

• a recirculating delay line, including a plurality of delay elements, propagating a delay pulse sequentially through said plurality of delay elements and generating a plurality of delay outputs each representative of a different position of said delay pulse in said recirculation delay line;
• a plurality of latch elements each having a first input connected to a respective one of said delay outputs of said recirculating delay line and a second input receiving said input signal, each of said plurality of latch elements latching one of its first and second inputs responsive to the other of said first and second inputs, and generating a latch output responsive thereto;
• a plurality of counters, each having an input connected to an output of a preselected one of said delay elements in said recirculating delay line, each of said counters providing an additional timing measurement of said input signal;
• wherein latch outputs of said plurality of latch elements collectively represent a timing measurement of said input signal.

A system for measuring a timing of an input signal applied thereto, said system comprising:

• a delayed pulse generating circuit sequentially generating a plurality of fine timing signals during a fine timing cycle on corresponding ones of a plurality of delayed pulse generating circuit outputs based on a position of a delay pulse within a delay line, said delay line including a plurality of delay elements;
• a signal processing section connected to said delayed pulse generating circuit generating, responsive to said input signal, a fine timing output representative of said plurality of fine timing signals;
• first counter means, connected to said delayed pulse generating circuit, receiving therefrom a first signal corresponding to one of said plurality of fine timing signals as a first clock signal, for generating a first count responsive to said input signal based on said first clock signal;
• second counter means, connected to said delayed pulse generating circuit, for generating a second count responsive to said input signal based on a second signal corresponding to one of said plurality of fine timing signals as a second clock signal;
• a multiplexer receiving said first count and said second count and selectively providing one of said first and second counts as a multiplexer output;
• wherein said multiplexer output is a coarse timing measurement of said input signal and said fine timing output is a fine timing measurement of said input signal.

A method of measuring a timing of an input signal, said method comprising the steps of:

• sequentially generating a plurality of fine timing signals during a fine timing cycle based on a position of a delay pulse within a delay line, said delay line including a plurality of delay elements;
• generating, responsive to said input signal, a fine timing output representative of said plurality of fine timing signals;
• generating a first count responsive to a first clock signal corresponding to one of said plurality of fine timing signals;
• generating a second count responsive to a second clock signal corresponding to one of said plurality of fine timing signals;
• and
• selectively providing one of said first count and said second count as a coarse count output;
• wherein said coarse count output is a coarse timing measurement of said input signal and said fine timing output is a fine timing measurement of said input signal.

A method of measuring a timing of an input signal, said method comprising the steps of:

• sequentially generating, in a delay line including a plurality of delay elements, a plurality of fine timing signals at outputs of said delay elements during a fine timing cycle based on a position of a delay pulse within the delay line;
• generating first timing information, responsive to said input signal, based on at least one delay element output in a first portion of said delay element outputs;
• generating second timing information, responsive to said input signal, based on at least one delay element output in a second portion of said delay element outputs;
• presenting said first timing information and said second timing information to an output latch;
• and
• latching said first timing information and said second timing information with said output latch to provide a timing measurement of said input signal.

A method of measuring a timing of an input signal, said method comprising the steps of:

• sequentially generating, in a delay line including a plurality of delay elements, a plurality of fine timing signals at outputs of said delay elements during a fine timing cycle based on a position of a delay pulse within the delay line, each of said fine timing signals representing a different position of said delay pulse within said delay line;
• generating, responsive to said input signal, fine timing information indicative of a position of said delay pulse in a portion of said delay line, said fine timing information corresponding to a least significant portion of a timing measurement of said input signal;
• generating, responsive to said input signal, coarse timing information corresponding to a most significant portion of said timing measurement based on at least one of said plurality of delay element outputs;
• and
• latching said coarse timing information.

An apparatus for producing an indication of a time difference between two pulses, said apparatus comprising:

• delay means, adapted to receive a first pulse, for delaying said first pulse in increments between its input and its output, said output of said delay means being connected to said input of said delay means to recirculate the first pulse, and for generating an increment output indicative of an increment status of said delay means, said increment output having a plurality of possible states each of which represents a different increment of said delay line;
• counting means for counting a number of times said delay means recirculates said first pulse;
• and
• receiving means, adapted to receive a second pulse, for producing an output indicative of both a count of said counting means and said delay means increment output, at a time of receiving said second pulse,
• wherein said receiving means includes a latch which is clocked by said second pulse to store an increment output of the delay means and a count of the counting means.

A method of measuring a timing of an input signal, said method comprising the steps of:

• sequentially generating, in a delay line including a plurality of delay elements, a plurality of fine timing signals at outputs of said delay elements during a fine timing cycle based on a position of a delay pulse within the delay line, each of said fine timing signals representing a different position of said delay pulse within said delay line;
• generating, responsive to said input signal, a pulse selection output comprising a plurality of outputs having a first value and a single output having a second value different from said first value, said single output being indicative of said position of said delay pulse in said delay line;
• generating, based on said pulse selection output, fine timing information corresponding to a least significant portion of a timing measurement of said input signal;
• and
• generating, responsive to said input signal, coarse timing information corresponding to a most significant portion of said timing measurement based on at least one of said plurality of delay element outputs.