RF Receiver Gain and Phase Compensation for Switched LNA Transients
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Solution Overview
Problem
RF receivers experience abrupt gain and phase discontinuities due to the dynamic changes in switched Low Noise Amplifier (LNA) stages, leading to gain transients and phase discontinuities, which are undesirable in wireless communication devices.
Innovation Solution
A digital gain normalization loop and digital phase compensation block are implemented to dynamically adjust the signal, normalizing the gain and compensating for phase shifts caused by LNA state changes, thereby avoiding abrupt steps and transients in the received signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If switched LNA stages are dynamically changed to control signal amplification, then receiver sensitivity is improved under weak signal conditions, but abrupt gain and phase discontinuities occur in the received signal
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing compensation values for gain and phase discontinuities in a lookup table before they occur. When LNA switching is detected, the corresponding compensation values are immediately retrieved and applied to the ADC output, preventing the discontinuities from affecting the received signal quality.
Solution Approach 2:
The patent implements feedback by monitoring the state of switched LNA stages and using this information to dynamically adjust compensation parameters. The system continuously detects LNA switching events and applies real-time compensation to maintain signal continuity, creating a closed-loop control mechanism that stabilizes gain and phase.
2Adaptability or versatility
If AGC unit dynamically changes the state of switched LNA stages to adapt to varying signal conditions, then receiver adaptability is improved, but gain transients and phase discontinuities are introduced
Solution Approach 1:
The patent introduces an intermediary compensation mechanism between the switched LNA stages and the signal processing chain. This intermediary layer includes compensation logic that calculates and applies correction values for gain and phase discontinuities, acting as a mediator that allows LNA switching while maintaining signal stability.
Solution Approach 2:
The patent applies parameter changes by dynamically adjusting compensation parameters (gain and phase correction values) based on the detected LNA state. When LNA switching occurs, the system changes the compensation parameters to counteract the expected discontinuities, thereby maintaining reliable signal output despite the adaptive LNA configuration changes.
Data Source
AI summary
Dynamic gain and phase compensation is provided in a radio frequency (RF) receiver (106) including at least one switched Low Noise Amplifier (LNA) (212) coupled to an RF gain control unit (226) providing a gain control signal to the at least one switched LNA (212) for control thereof. The RF receiver also includes an analog-to-digital (A/D) converter (222) for digitizing the RF signal and outputting an N-bit digital signal to the RF gain control unit (226). The method for gain compensation includes dynamically adjusting the N-bit digital signal to compensate for the at least one switched LNA (212) in response to the gain control signal. The method for phase compensation includes dynamically normalizing the N-bit digital signal into an M-bit signal range to derive an M-bit digital signal, where M≦N and dynamically phase adjusting the M-bit digital signal to compensate for the at least one switched LNA (212) in response to the gain control signal.