Dual-Port RAM Predistortion Parameter Calculation Circuit
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Solution Overview
Problem
Implementing a predistortion circuit in devices with programmable logic is challenging due to the need for accurate calculation of parameters to counteract distortion in power amplifiers, especially in scenarios with varying power levels and pulsed envelopes.
Innovation Solution
A circuit and method utilizing dual-port random access memory and an embedded processor to capture and process input signal data, calculate parameters for a predistortion circuit, and adapt coefficients in response to changing power conditions, ensuring effective distortion reduction across different power levels and signal envelopes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If a predistortion circuit is implemented in a device with programmable logic, then distortion in power amplifier outputs can be reduced, but the complexity of parameter calculation and adaptation increases
Solution Approach 1:
The parameter calculation process is divided into distinct functional blocks: power measurement circuit for capturing signal power, dual-port RAM for storing power samples, processing circuit for calculating statistical parameters, and adaptation circuit for updating predistortion coefficients. Each block performs a specific function, making the overall complex system manageable and implementable in programmable logic devices.
Solution Approach 2:
The system performs preliminary power measurement and statistical parameter calculation before applying predistortion. Power samples are collected and stored in advance in the dual-port RAM, allowing the processing circuit to calculate mean power, variance, and other statistical characteristics before the actual predistortion parameter adaptation occurs.
2Measurement precision
If predistortion parameters are calculated using statistical parameters of power samples, then accurate distortion reduction can be achieved, but the time and computational resources required increase
Solution Approach 1:
The system calculates only the essential statistical parameters (mean power, variance, standard deviation) needed for predistortion adaptation rather than performing complete signal analysis. The dual-port RAM stores a sufficient number of power samples to achieve accurate statistical estimation without requiring excessive storage or computation time.
Solution Approach 2:
The patent replaces complex continuous-time power measurement and analysis with discrete-time digital sampling and statistical processing. The power measurement circuit converts analog power signals to digital samples, which are then processed using digital statistical methods in the processing circuit, enabling efficient computation in programmable logic devices.
3Measurement precision
If power samples are stored over a predetermined period of time, then accurate statistical parameters can be obtained, but the memory requirements increase
Solution Approach 1:
The dual-port RAM stores a predetermined but limited number of power samples sufficient for accurate statistical estimation. The system balances the number of stored samples against memory constraints, using just enough samples to achieve reliable mean power, variance, and standard deviation calculations without requiring excessive storage capacity.
4Adaptability or versatility
If the predistortion circuit adapts to varying power levels, then distortion reduction remains effective across different conditions, but the adaptation mechanism complexity increases
Solution Approach 1:
The adaptation circuit continuously monitors power samples stored in the dual-port RAM, calculates current statistical parameters, compares them with previous values, and updates predistortion coefficients accordingly. This feedback mechanism enables automatic adaptation to varying power levels and signal conditions without requiring complex manual configuration or external control.
Solution Approach 2:
The predistortion circuit transitions from static fixed parameters to dynamic adaptive parameters. The processing circuit calculates statistical parameters in real-time from incoming power samples, and the adaptation circuit dynamically adjusts predistortion coefficients based on current signal conditions, enabling the system to adapt to changing power levels and envelope characteristics.
Data Source
AI summary
A circuit for receiving a sample of an input signal to be used to calculate parameters for a predistortion circuit in an integrated circuit is described. The circuit comprises a power measurement circuit coupled to receive the input signal; a first port of a dual port random access memory for receiving data associated with power of the input signal over a predetermined period of time; and a second port of a dual port random access memory for generating the data associated with the power of the input signal stored over the predetermined period of time. A method of receiving a sample of an input signal to be used to calculate parameters for a predistortion circuit in an integrated circuit is also described.