AC-Coupled Transceiver Calibration for DC-AC Swing Matching
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Solution Overview
Problem
AC-coupled transceivers suffer from mismatches between DC and AC voltage swings and duty cycle changes due to process, voltage, and temperature variations, leading to inter-symbol interference (ISI), particularly in high-speed applications, with existing solutions being complex, power-hungry, and inefficient.
Innovation Solution
Employing calibration circuitry with a peak detector to identify minimum and maximum voltages, comparing DC and AC swings, and adjusting resistors and capacitors to minimize mismatches, while also calibrating duty cycles using an ADC and calibration engine to optimize component parameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If AC-coupled transceivers reduce AC voltage swing to lower power consumption, then power efficiency is improved, but mismatch between DC and AC voltage swings increases causing inter-symbol interference
Solution Approach 1:
The patent dynamically adjusts circuit parameters (resistor values, capacitor values, bias voltages) based on detected DC and AC voltage swing characteristics to minimize mismatch and eliminate inter-symbol interference while maintaining reduced power consumption operation
2Reliability
If existing calibration solutions are implemented to reduce mismatch, then signal integrity is improved, but device complexity and power consumption increase
Solution Approach 1:
The calibration circuit automatically detects voltage swing mismatches and performs self-adjustment through feedback control, eliminating the need for external calibration equipment or complex manual adjustment mechanisms while reducing device complexity
Solution Approach 2:
The patent employs feedback mechanisms where the calibration circuit continuously monitors DC and AC voltage swings and adjusts circuit parameters in real-time to maintain optimal signal integrity without increasing overall system complexity
Data Source
AI summary
A circuit includes a receiver coupled to an input node and includes a transimpedance amplifier (TIA). The input node is to be coupled to a transmitter over a channel. Calibration circuitry is coupled to the input node and to modify a resistance of a feedback resistor of the receiver by applying a plurality of control values. The calibration circuitry is to generate, for each applied control value, a first digital code for a direct current (DC) swing and a second digital code for an alternating current (AC) swing at the input node. The calibration circuitry is to determine a final control value of the plurality of control values that minimizes a difference between the first and second digital codes.