Adaptive Band-Pass Amplifier Tuning for Clock Signal Alignment
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Solution Overview
Problem
Band-pass amplifiers in high-speed serial input-output communication links face challenges in matching the peak response to the center frequency of narrow band clock signals, as this depends on the inductance of the inductor-load and capacitance, requiring adaptive tuning to align with received signals.
Innovation Solution
A control loop comprising a control circuit and finite state machine tunes the band-pass amplifier by adjusting the reactance of the load through switching capacitive circuits in or out, or by changing bias currents, to align the peak frequency with the received clock signal, using a counter to decrement and switch out capacitors to shift the frequency higher.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the peak response of the amplifier is fixed during fabrication, then the manufacturing process is simple, but the amplifier cannot adapt to match the center frequency of received clock signals
Solution Approach 1:
The patent implements dynamic frequency tuning by making the inductor load adjustable through switching networks. The inductance value can be dynamically changed by switching different inductor segments in or out, allowing the amplifier's peak frequency to adapt to match received clock signals while maintaining a relatively simple fabrication process
Solution Approach 2:
The patent changes the electrical parameters of the amplifier by adjusting the effective inductance and capacitance values through switching networks. By changing these parameters, the resonant frequency of the amplifier can be tuned to match the center frequency of received clock signals, achieving frequency adaptability without complex fabrication processes
2Adaptability or versatility
If capacitive circuits are switched in or out to tune the amplifier, then the frequency can be adjusted, but the device complexity increases
Solution Approach 1:
The patent segments the capacitive load into multiple discrete capacitor units that can be independently switched in or out. This segmentation allows for fine-grained frequency tuning by selectively combining different capacitor values, achieving a wide tuning range while keeping each individual switching element relatively simple
Solution Approach 2:
The patent employs a nested switching network structure where smaller capacitor units are combined in hierarchical groups. This nested arrangement allows for efficient frequency tuning by activating only the necessary switching levels, reducing the overall complexity of the switching network while maintaining extensive tuning capability
Data Source
AI summary
An adaptive tuning circuit to maximize the output signal amplitude of a band-pass amplifier, comprising a control circuit to tune the peak frequency of the amplifier by monitoring the change in the output signal amplitude over two successive time sampling intervals. In some embodiments, the control circuit comprises an envelope detector and a switched capacitor circuit to provide voltages indicative of the difference in the output signal amplitude over two successive time intervals. Other embodiments are described and claimed.