Coherent Receiver Bias Circuit Temperature Compensation
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Solution Overview
Problem
Coherent receivers in wireless communication devices face challenges in maintaining constant gain characteristics over temperature variations, affecting the accuracy of feedback control paths in monitoring and controlling transmitter parameters.
Innovation Solution
A method is introduced where a bias current is generated by subtracting a temperature-dependent current from a bandgap voltage divided by a resistance, and this bias current is provided to a feedback digital-to-analog converter to output a current proportional to the bias current, thereby offsetting temperature-dependent variations in the feedback control path.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional feedback control path is used in a wireless communication device, then the transmitter parameters can be monitored and controlled, but the gain characteristics of the feedback control path vary with temperature, reducing measurement precision
Solution Approach 1:
The patent applies preliminary anti-action by generating a compensation current that is proportional to temperature variations before these variations affect the feedback control path. This compensation current is injected into the feedback DAC to preemptively counteract the temperature-dependent gain variations, thereby maintaining stable measurement precision across temperature changes
Solution Approach 2:
The patent changes the electrical parameters (current) in the feedback control path to compensate for temperature effects. By adjusting the compensation current based on temperature-dependent current measurements, the system dynamically modifies operating parameters to maintain constant gain characteristics despite temperature variations
2Reliability
If temperature compensation circuitry is added to the feedback control path, then temperature dependence is reduced, but device complexity increases
Solution Approach 1:
The patent merges the temperature compensation function with the existing feedback control path by injecting the compensation current directly into the feedback DAC. This integration approach combines multiple functions (temperature sensing, compensation current generation, and feedback control) into a unified circuit architecture, achieving temperature stability without proportionally increasing device complexity
Solution Approach 2:
The patent uses an intermediary compensation current as a mediator between the temperature variations and the feedback control path. This compensation current acts as a buffer that translates temperature changes into corrective electrical signals, indirectly managing temperature effects while maintaining a relatively simple circuit structure
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach effectively reduces or eliminates temperature dependence in the feedback control path, ensuring consistent performance and accurate monitoring and control of transmitter parameters across varying temperatures.
Implementation Method 1
generating a first current equal to a bandgap voltage divided by a resistance selected to approximately match a process resistance integral to a receiver
Implementation Method 2
generating a second current equal to temperature-dependent current multiplied by a predetermined scaling factor
Data Source
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AI summary
To reduce temperature dependence of a coherent receiver in a wireless communication device, a first current is generated equal to a bandgap voltage divided by a resistance selected to approximately match a process resistance integral to a receiver. A second current is generated equal to temperature-dependent current multiplied by a predetermined scaling factor and subtracted from the first current to generate a bias current for supply to a receiver.