Capacitive Signal Conversion for Wide-Range Digital Transmitters
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Solution Overview
Problem
Current digital transmitters in wireless communication systems, such as 3G mobile communication, face a limitation in dynamic power range due to the minimum size of semiconductor processes, with switch-mode power amplifiers only capable of generating power up to −45 dBm, which is insufficient to meet the required −78 dBm range.
Innovation Solution
The implementation of a digital transmitting apparatus that includes a plurality of signal converting devices with capacitive circuits, where the capacitive circuits are used to generate lower power levels, allowing the apparatus to extend its dynamic range by generating output signals down to −78 dBm, overcoming the limitations of semiconductor process sizes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If switch-mode power amplifier with minimum size is used, then device complexity is reduced, but power range is limited to −45 dBm minimum
Solution Approach 1:
The transmitter is divided into multiple independent switch-mode power amplifiers, each handling a specific power range segment. This segmentation allows each amplifier to operate within its optimal power range while collectively covering the full required dynamic range from 0 dBm to −78 dBm, resolving the contradiction between simplified device structure and extended power range.
Solution Approach 2:
Multiple power amplifiers are nested in a hierarchical structure where higher-power amplifiers handle stronger signals and lower-power amplifiers handle weaker signals. This nested architecture enables the system to achieve wide dynamic range coverage without requiring each individual amplifier to cover the entire range, thus maintaining simplicity while extending power capabilities.
2Power
If various components (DAC, low pass filter, programmable gain amplifier, modulator, pre-driver) are used, then power range from 0 dBm to −78 dBm is achieved, but area occupied is large
Solution Approach 1:
The invention extracts and removes unnecessary intermediate components (low pass filter, programmable gain amplifier, modulator, pre-driver) from the traditional transmitter architecture, retaining only the essential digital-to-analog conversion and power amplification functions. This extraction achieves the full power range with significantly reduced transistor count and smaller area occupation.
Solution Approach 2:
Analog components are replaced with digital switch-mode power amplifiers that directly convert digital signals to analog output. This substitution eliminates the need for complex analog filtering and gain control circuits, reducing both the area occupied and the number of components while maintaining the required power range from 0 dBm to −78 dBm.
3Manufacturing precision
If minimum size semiconductor process is used, then manufacturing precision is improved, but dynamic range extension is limited
Solution Approach 1:
The system dynamically selects and activates appropriate power amplifiers based on the required output power level. This dynamic adaptation allows the transmitter to extend its dynamic range beyond what a single minimum-size amplifier can provide, while still benefiting from the manufacturing precision of modern semiconductor processes. The dynamic range is extended to 0 dBm to −78 dBm through coordinated operation of multiple amplifiers.
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 extends the dynamic power range of digital transmitters from 0 dBm to −78 dBm, providing a wider range than conventional systems and making the power level of output signals independent of temperature variations.
Implementation Method 1
a first capacitive circuit, coupled between an output terminal of the first converting circuit and a reference voltage, wherein the first converting circuit is arranged to generate a first converting signal on the output terminal of the first converting circuit according to the first inputting signal
Data Source
AI summary
A signal converting device includes: a first converting circuit arranged to receive a first inputting signal; and a first capacitive circuit coupled between an output terminal of the first converting circuit and a reference voltage; wherein the first converting circuit is arranged to generate a first converting signal on the output terminal of the first converting circuit according to the first inputting signal.