Local Oscillator Duty Cycle Calibration for RF Interference Tolerance
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Solution Overview
Problem
RF receivers face challenges in tolerating interfering signals, leading to bit error rate degradation and signal-to-noise ratio degradation due to second-order and third-order distortion effects, which are exacerbated by the duty cycle of the local oscillator signal affecting noise figure and linearity.
Innovation Solution
A local oscillator module with a feedback circuit that adjusts the duty cycle of the local oscillator signal by comparing a voltage signal representing the current duty cycle with a desired voltage signal, using a processor to minimize the difference and adjust the pulse width to maintain optimal performance parameters such as noise figure and linearity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the duty cycle of the local oscillator signal is adjusted to improve linearity and noise figure, then the receiver's ability to tolerate interfering signals improves, but the device complexity increases due to the feedback circuit
Solution Approach 1:
The patent implements a feedback circuit that monitors the duty cycle of the local oscillator signal and adjusts it dynamically to maintain optimal values for linearity and noise figure. The feedback mechanism continuously compares the actual duty cycle with a target value and modifies the oscillator control voltage accordingly, enabling the receiver to adapt to varying interference conditions and maintain high reliability without manual intervention.
2Manufacturing precision
If traditional IP2 calibration is performed by adjusting mixer bias voltage in manufacturing environment, then linearity improvement is achieved, but loss of time occurs due to manual calibration process and external test equipment requirements
Solution Approach 1:
The patent enables the receiver to perform its own IP2 calibration automatically using an integrated feedback circuit that monitors and adjusts the local oscillator duty cycle without requiring external test equipment or manual intervention. The system self-calibrates by detecting duty cycle deviations and automatically adjusting the oscillator control voltage to restore optimal linearity, eliminating the time-consuming manual calibration process and allowing production to proceed without dedicated calibration equipment.
Data Source
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AI summary
A local oscillator (LO) module comprises a local oscillator and a feedback circuit. The local oscillator, biased at a supply voltage, generates a local oscillator signal having a duty cycle. The feedback circuit makes an absolute adjustment of the duty cycle of the local oscillator signal in response to a difference between a first voltage signal, representing a voltage level of the local oscillator signal, and a second voltage signal, representing a voltage level of a portion of the supply voltage corresponding to a desired duty cycle for the local oscillator signal.