Transmitter Delay Mismatch Compensation via Tunable All-Pass Filter
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Solution Overview
Problem
Existing transmitter devices face challenges in compensating for delay mismatches in their analog parts, which lead to distortion and affect signal quality, particularly in GSM/EDGE systems, where existing solutions either require tight component variations difficult to achieve in mass production or lack compensation for delay mismatches.
Innovation Solution
A transmitter device with a digital and analog part, incorporating a digital modulator, digital-to-analog converters, and filter units that store compensation filter values to adjust for delay mismatches, using a first-order all-pass filter with a tunable pole and zero constellation to compensate for delay mismatches in the analog part.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If tight component variations are designed to fulfill delay mismatch limits, then signal quality is improved, but manufacturing difficulty increases
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing compensation filter values in a table during the design phase. These values are determined based on expected delay mismatches and are readily available during mass production, eliminating the need for complex real-time calculations or tight component tolerances.
Solution Approach 2:
The patent changes the parameter of filter values dynamically based on the determined delay mismatch. By adjusting the filter values selected from pre-stored compensation values, the system compensates for delay mismatches without requiring tight component variations, thus resolving the contradiction between signal quality and manufacturing ease.
2Reliability
If complex compensation methods are used to correct delay mismatch, then signal quality is improved, but device complexity increases
Solution Approach 1:
The patent pre-calculates compensation filter values for various delay mismatch scenarios and stores them in a table. During operation, the system only needs to determine the actual delay mismatch and select the appropriate pre-computed values, avoiding complex real-time compensation calculations and reducing device complexity.
Solution Approach 2:
The patent uses a table to store copies of pre-computed compensation filter values. Instead of performing complex calculations during operation, the system copies the appropriate pre-stored values into the filter units, significantly simplifying the device architecture while maintaining compensation effectiveness.
3Reliability
If delay mismatch compensation is implemented, then image rejection is improved, but filter adjustment complexity increases
Solution Approach 1:
The patent pre-determines and stores compensation filter values for various delay mismatch conditions. The system automatically selects and applies the appropriate pre-stored values based on the measured delay mismatch, eliminating the need for manual filter adjustment and simplifying operation while maintaining image rejection performance.
Data Source
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AI summary
A transmitter device is provided which comprises a digital part (DP) and an analog part (AP). The transmitter device furthermore comprises a digital modulator (DM) in the digital part (DP) for receiving bits (MB) and for digitally modulating the receiving bits (MB). A first (IDAC; RDAC) and second digital-to-analog converter (QDAC; ODAC) are provided. The transmitter device furthermore comprises at least one filter unit (H1; HQ; Hl) which is arranged in the digital part (DP) and which is coupled between the first and/or second digital-to-analog converter (IDAC; QDAC) and the digital modulator (DM). A table unit (TU) is coupled to the at least one filter unit (H1; HQ) and is used to store pre- defined compensation filter values for the at least one filter unit (H1; HQ) which are required to compensate different delay mismatches in the analog part (AP) of the transmit¬ ter device. The filter values of the at least one filter unit (H1; HQ) are set to those compensa¬ tion filter values as stored in the table unit (TU) which correspond to a determined delay mismatch.