Four-Phase Generation Circuit With Feedback for 90° Phase Accuracy
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Solution Overview
Problem
Existing four-phase generation circuits face deviations from the intended 90° phase difference due to process variations and noise, which affect the accuracy and reliability of the generated quadrature signals.
Innovation Solution
A four-phase generation circuit with a feedback mechanism that adjusts the common mode voltage of the differential signal input to a polyphase filter, using an exclusive NOR or exclusive OR logic circuit and a low-pass filter to control the phase relationship between in-phase and quadrature outputs, ensuring accurate 90° phase separation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a polyphase filter is used to generate four-phase signals from a differential signal, then the circuit can operate at higher frequencies, but process variations cause deviations from the intended 90° phase difference between outputs
Solution Approach 1:
A feedback circuit monitors the actual phase difference between the in-phase and quadrature outputs of the polyphase filter and adjusts the common mode voltage of the differential signal to compensate for process variations. This closed-loop control ensures that the phase separation remains accurate at the desired operating frequency despite manufacturing tolerances.
Solution Approach 2:
The common mode voltage of the differential signal is used as a control parameter to adjust the phase separation. By varying this voltage parameter, the circuit can compensate for process variations and maintain accurate 90° phase difference between outputs while operating at higher frequencies.
2Manufacturing precision
If the common mode voltage of the differential signal is adjusted to compensate for phase deviations, then phase accuracy improves, but additional circuit complexity is introduced
Solution Approach 1:
The feedback circuit measures the phase difference between outputs and automatically adjusts the common mode voltage to maintain accurate phase separation. This automated closed-loop control improves phase accuracy without requiring manual calibration or complex adjustment mechanisms.
Solution Approach 2:
The common mode voltage acts as an intermediary control parameter that links the feedback signal to the phase separation adjustment. By using this intermediate parameter, the circuit achieves precise phase control through a relatively simple adjustment mechanism rather than directly modifying the polyphase filter structure.
Data Source
AI summary
Disclosed is a four-phase generation circuit, comprising a pair of input ports configured to receive a differential signal having a common mode voltage; a polyphase filter having a pair of polyphase filter input ports and first, second, third and fourth output ports; a first circuit configured to provide the differential signal with an adjusted common mode voltage to the pair of polyphase filter input ports; wherein the first, second third and fourth output ports are each configured to output a square-wave signal, with 90° phase separation between consecutive output signals; and a feedback circuit from the first, second, third and fourth outputs ports to the first circuit; wherein the feedback circuit is configured to provide a feedback signal to the first circuit to set the adjusted common mode voltage from the common mode voltage.