Patent ID: 6901339

Claim:
A method of measuring the level of a recurring data signal at selected times relative to a recurring reference associated with the data signal, the method comprising the steps of: (a) comparing the instantaneous voltage of a clock signal associated with the data signal to a clock threshold voltage to produce a logical clock signal; (b) delaying the logical clock signal by a selected first amount to produce a delayed logical clock signal; (c) comparing the instantaneous voltage of the data signal to be measured to a first data threshold voltage to produce a first logical data signal; (d) delaying the first logical data signal by a selected second amount to produce a first delayed logical data signal; (e) delaying the delayed logical clock signal by a selected third amount to produce a doubly delayed logical clock signal; (f) capturing the value of the first delayed logical data signal in response to the delayed logical clock signal; (g) capturing the value of the first delayed logical data signal in response to the doubly delayed logical clock signal; (h) generating the XOR of the value captured in step (f) and the value captured in step (g); (i) comparing the instantaneous voltage of the data signal to be measured to a second data threshold voltage to produce a second logical data signal; (j) delaying the second logical data signal by the selected second amount to produce a second delayed logical data signal; (k) capturing the value of the second delayed logical data signal in response to the delayed logical clock signal; (l) generating the XOR of the value captured in step (f) and the value captured in step (k); (m) generating the OR of the XOR values generated in steps (h) and (l); and (n) capturing the logical value of the OR operation generated in step (m).