Patent ID: 6944099

Claim:
An apparatus to accurately measure time periods, comprising: (a) a time measurement unit to receive an input of a reference clock and a high speed oscillating clock having a time period to be measured; the time measurement unit comprising: (i) an edge-launcher that receives the reference clock and the high speed oscillating clock and in response thereto generates a plurality of signals; (ii) a plurality of fast delay units arranged in a fast delay line, a plurality of slow delay units arranged in a slow delay line, and a plurality of latches; the first of the slow delay unit receiving a start signal generated by the edge-launcher, and the first of the fast delay units receiving a stop signal generated by the edge-launcher; one each slow delay unit interconnected with one each latch to one each fast delay unit, and the first of the slow delay unit to receive a second start signal and the first of the fast delay units to receive a second stop signal to obtain a calibration of the time measurement unit; (iii) a plurality of combinatorial logic, one combinatorial logic receiving the output of one latch; and (iv) a linear-to-binary coder connected to the output of the plurality of combinatorial logic; (b) a cycle counter having a plurality of counters; each counter to count and store the number of the high speed oscillating clock cycles within a time period of alternating reference clock cycles; and (c) a register to store the output of the linear-to-binary coder and the cycle counter.