High speed peak amplitude comparator
First Claim
1. A peak amplitude comparator comprising:
- an input circuit having an input terminal coupled to receive an input signal, and configured to store a first signal with an amplitude that is substantially equal to a peak amplitude of the input signal minus a predetermined voltage drop and to generate the stored first signal at an output terminal;
a reference circuit having an input terminal coupled to receive a reference voltage and configured to generate at an output terminal a second signal with an amplitude that is substantially equal to the reference voltage minus the predetermined voltage drop; and
a comparator having a first terminal coupled to receive the first signal and a second terminal coupled to receive the second signal.
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Abstract
Various methods and circuits for implementing high speed peak amplitude comparison. The invention achieves higher speed of operation by eliminating the slow feedback loop commonly employed in peak detection. In one embodiment, the invention directly compares a signal that represents the peak amplitude of the input signal minus a small voltage drop, to a modified reference voltage. The modified reference voltage corresponds to the reference voltage that is adjusted to compensate for the small voltage drop in the maximum input voltage. In another embodiment, the invention implements a differential version of the peak amplitude comparator to obtain better noise rejection and reduced effective offset among other advantages.
22 Citations
14 Claims
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1. A peak amplitude comparator comprising:
- an input circuit having an input terminal coupled to receive an input signal, and configured to store a first signal with an amplitude that is substantially equal to a peak amplitude of the input signal minus a predetermined voltage drop and to generate the stored first signal at an output terminal;
a reference circuit having an input terminal coupled to receive a reference voltage and configured to generate at an output terminal a second signal with an amplitude that is substantially equal to the reference voltage minus the predetermined voltage drop; and
a comparator having a first terminal coupled to receive the first signal and a second terminal coupled to receive the second signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
- an input circuit having an input terminal coupled to receive an input signal, and configured to store a first signal with an amplitude that is substantially equal to a peak amplitude of the input signal minus a predetermined voltage drop and to generate the stored first signal at an output terminal;
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9. A differential peak amplitude comparator comprising:
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an input circuit having first and second input terminals coupled to respectively receive differential first and second input signals, and configured to generate at an output terminal a first signal with an amplitude that is substantially equal to a peak amplitude of either of the first and second input signals minus a predetermined voltage drop;
a reference circuit having an input terminal coupled to receive a reference voltage and configured to generate at an output terminal a second signal with an amplitude that is substantially equal to the reference voltage minus the predetermined voltage drop; and
a comparator having a first terminal coupled to receive the first signal and a second terminal coupled to receive the second signal. - View Dependent Claims (10, 11)
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12. A method for comparing a peak amplitude of an input signal to a reference voltage, comprising:
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storing, on a first node, a first signal having an amplitude that is substantially equal to a peak amplitude of the input signal minus a predetermined voltage drop;
generating a second signal having an amplitude that is substantially equal to the reference voltage minus the predetermined voltage drop; and
comparing a magnitude of the first signal to a magnitude of the second signal. - View Dependent Claims (13, 14)
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Specification