Transmission system control circuit including comparator apparatus
AssigneeLucent Technologies Inc.
InventorRalph Urbansky
Life of this patent
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Abstract
The invention relates to a transmission system comprising a control circuit which circuit includes a comparator (18, 19, 20; 25 to 29; 46; 50 to 52, 57 to 60) for comparing a first input signal and a second input signal. For reducing the low-frequency phase error, the comparator (18, 19, 20; 25 to 29; 46; 50 to 52, 57 to 60) is provided for changing the state of a first comparing signal derived from the first input signal and/or the state of a second comparing signal derived from the second input signal, or the state of the output signal resulting from a combination of the two comparing signals at instants denoted by an auxiliary signal whose frequency deviates from the frequency of the signal to be changed.
Claims9
A control circuit for use in a transmission system including a comparator having a first input, a second input and an output for comparing input signals supplied to the first and second inputs and yielding a result of the comparing at the output, the comparator further comprising:
- a first converter circuit supplied with a first input signal at a first frequency and an auxiliary signal for generating a changed-state first comparing signal;
- a second converter circuit supplied with a second input signal at a second frequency and the auxiliary signal for generating a changed-state second comparing signal;
- and
- a comparative counter having an enable input, a clock input and an output, the changed-state first comparing signal being supplied to the enable input and the changed-state second comparing signal being supplied to the clock input, the comparative counter being responsive to the changed-state first and second comparing signals to count clocks in the changed-state second comparing signal for an interval defined by the changed-state first signal being in a predetermined state and to supply its count at its output, wherein the auxiliary signal has a frequency that deviates from the frequency of the first input signal.
A control circuit for use in a transmission system including a comparator having a first input, a second input and an output for comparing input signals supplied to the first and second inputs and yielding a result of the comparing at the output, the comparator further comprising:
- a first counter having an input and an output, which is responsive to a first input signal having a first frequency supplied to its input for generating a first comparing signal having at least first and second states at its output;
- a second counter having an input and an output, which is responsive to a second input signal supplied to its input for generating a second comparing signal having at least first and second states at its output;
- first adapting circuit having a first input, a second input and an output, the first comparing signal being supplied to the first input of the first adapting circuit and being responsive to an auxiliary signal being supplied to the second input of the first adapting circuit and having a frequency that deviates from the first frequency of the first input signal being supplied to the input of the first counter for changing the state of the first comparing signal to yield the changed state first comparing signal at its output;
- a second adapting circuit having a first input, a second input and an output, the second comparing signal being supplied to the first input of the second adapting circuit and being responsive to the auxiliary signal being supplied to the second input of the second adapting circuit for changing the state of the first comparing signal to yield the changed state second comparing signal at its output;
- and
- a subtracter having a first input, a second input and an output, the output of the first adapting circuit and the output of the second adapting circuit being in circuit with the first input and second input, respectively, of the subtracter for subtracting the changed state first comparing signal and the changed state second comparing signal and for yielding a value representative of the subtraction result at its output.
Dependencies are inferred from the claim text.