Programmable TX-CTF Current Control for Linearity and Battery Drain
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Solution Overview
Problem
Designing a transmit continuous-time filter (TX-CTF) for multi-mode cellular handsets that meets performance criteria such as high current drive capability, high linearity, low input referred noise, and low bandpass ripple while minimizing current consumption to extend battery life and reduce battery size is challenging, as increasing current consumption leads to high battery drain.
Innovation Solution
A programmable-current TX-CTF system that includes amplifier and passive circuitry with programmable bias current control logic, adjusting bias current based on transmitter control signals like modulation mode, band, and power signals to optimize performance according to operating conditions, using passive upconversion mixers to reduce power consumption and maintain linearity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If TX-CTF current is increased to meet performance requirements (high current drive capability, high linearity, low input referred noise), then performance is improved, but battery current drain increases
Solution Approach 1:
The patent implements dynamic current control by making the bias current programmable and adjustable based on operating conditions. The TX-CTF transitions from a static high-current design to a dynamic system where current is optimized in real-time according to modulation mode, frequency band, and power level requirements, resolving the contradiction between maintaining high performance and reducing power consumption.
Solution Approach 2:
The patent changes the key parameter of bias current from a fixed high value to a programmable variable parameter. By adjusting the bias current based on specific operating conditions (different modulation modes, frequency bands, and power levels), the system achieves optimal performance only when required while minimizing power consumption during normal operation, thus resolving the technical contradiction.
2Use of energy by moving object
If TX-CTF current is minimized to extend battery life, then battery drain is reduced, but performance requirements (high current drive capability, high linearity) cannot be met
Solution Approach 1:
The system dynamically adjusts bias current based on real-time operating conditions. During normal operation with lower performance requirements, the system operates at minimal current to extend battery life. When specific conditions are detected (certain modulation modes, frequency bands, or power levels), the system automatically increases current to meet performance requirements, thus resolving the contradiction between power minimization and performance maintenance.
Solution Approach 2:
The patent incorporates feedback mechanisms where control logic monitors operating conditions (modulation mode, frequency band, power level) and adjusts bias current accordingly. This closed-loop control ensures that performance requirements are met only when necessary, while minimizing power consumption during normal operation, resolving the contradiction between battery life extension and performance maintenance.
3Use of energy by moving object
If programmable bias current control is implemented to optimize performance, then power consumption is minimized, but device complexity increases
Solution Approach 1:
The control logic is designed to handle multiple functions through a single integrated unit that responds to different input conditions (modulation mode, frequency band, power level) and adjusts bias current accordingly. This universal control mechanism manages various operating scenarios without requiring separate control circuits for each function, thus minimizing the increase in device complexity while achieving power optimization.
Data Source
AI summary
A programmable-current transmit continuous-time filter (TX-CTF) system can be included in a radio frequency (RF) transmitter. The input of the TX-CTF can receive a baseband transmission signal, and the output of the TX-CTF can be provided to an upconversion mixer for conversion to RF for transmission. The TX-CTF includes amplifier circuitry and passive circuitry that together define the filter parameters. The TX-CTF further includes programmable current circuitry that provides a programmable bias current to the amplifier circuitry. The TX-CTF system also includes control logic that receives one or more transmitter control signals and, in response, generates signals that control the bias current provided to the TX-CTF.