Timing skew error correction apparatus and methods
First Claim
1. An analog signal sampling circuit, comprising:
- a first signal capture module to sample a first phase of an analog signal by capturing a magnitude of the first phase upon receipt of a clock transition from a first capture clock;
a first clock delay module coupled to the first signal capture module to delay a common clock by a first delay period to generate the first capture clock;
a second signal capture module to sample a second phase of the analog signal by capturing a magnitude of the second phase upon receipt of a clock transition from a second capture clock; and
a second clock delay module coupled to the common clock and to the second signal capture module to delay the common clock by a second delay period to generate the second capture clock.
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Accused Products
Abstract
Apparatus and methods disclosed herein operate to compensate for skew between inverse phases (e.g., differential phases) of an analog signal appearing at the inputs of an analog signal capture circuit such as a track-and-hold or sample-and-hold circuit associated with an ADC or similar device. Each of two capture clocks is used to capture one of the inverse phases. One or more delay circuits are configured to create a differential delay between clock transitions associated with the two capture clocks. The differential delay is proportional to the input skew between the inverse phases. The phases are consequently sampled at substantially identical points on a phase domain axis. Embodiments operate to create phase sampling synchronicity and to thereby decrease the amplitude of a common-mode signal component that results from the skew. Increased linearity and decreased distortion may result.
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Citations
19 Claims
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1. An analog signal sampling circuit, comprising:
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a first signal capture module to sample a first phase of an analog signal by capturing a magnitude of the first phase upon receipt of a clock transition from a first capture clock; a first clock delay module coupled to the first signal capture module to delay a common clock by a first delay period to generate the first capture clock; a second signal capture module to sample a second phase of the analog signal by capturing a magnitude of the second phase upon receipt of a clock transition from a second capture clock; and a second clock delay module coupled to the common clock and to the second signal capture module to delay the common clock by a second delay period to generate the second capture clock. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A method of analog signal capture, comprising:
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delaying a common clock by a first delay period to produce a first capture clock; sampling a first phase of an analog signal by capturing a magnitude of the first phase upon receipt of a clock transition from the first capture clock; delaying the common clock by a second delay period to produce a second capture clock; and sampling a second phase of the analog signal by capturing a magnitude of the second phase upon receipt of a clock transition from the second capture clock. - View Dependent Claims (14, 15, 16, 17, 18)
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19. An analog signal sampling circuit, comprising:
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a first track-and-hold circuit to capture a magnitude of a first phase of an analog signal upon receipt of a clock transition from a first capture clock; at least one first inverter coupled to the first track-and-hold circuit to provide a first propagation delay to a common clock to produce the first capture clock; a first power supply coupled to the first inverter to provide a first supply voltage to the first inverter to adjust a period of the first propagation delay in proportion to the first supply voltage; a second track-and-hold circuit to capture a magnitude of a second phase of the analog signal upon receipt of a clock transition from a second capture clock; at least one second inverter coupled to the second track-and-hold circuit to provide a second propagation delay to the common clock to produce the second capture clock; a second power supply coupled to the second inverter to provide a second supply voltage to the second inverter to adjust a period of the second propagation delay in proportion to the second supply voltage; a differential phase detector coupled to the first track-and-hold circuit and to the second track-and-hold circuit, the differential phase detector to determine a phase difference between the first phase and the second phase; and a delay control module coupled to the differential phase detector to act upon the first and second power supplies to adjust the first and second supply voltages to the first and second inverters in proportion to the phase difference such that the first phase and the second phase are sampled at substantially identical points on a phase axis associated with the analog signal.
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Specification