Delta-Sigma Transmission Circuit With Discrete Envelope Control
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Solution Overview
Problem
Conventional transmission circuits for communication devices face challenges in achieving high efficiency and linearity while maintaining a small size, as they often require steep filter characteristics to remove quantization noise, leading to increased power consumption and circuit size, and potential signal quality deterioration.
Innovation Solution
A transmission circuit design that includes a signal generation section, amplitude calculation section, delta-sigma modulation section, and amplitude modulation section, which uses discrete value signals to reduce envelope variation and quantization noise, allowing for a non-steep filter characteristic and improved efficiency and linearity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional transmission circuits use steep filter characteristics to remove quantization noise, then signal quality is improved, but power consumption increases and circuit size increases
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing amplitude information in a lookup table before delta-sigma modulation. The amplitude calculation section computes amplitude values in advance and stores them, so that during modulation the stored values are directly used without requiring steep filters. This preliminary preparation eliminates quantization noise at its source, resolving the contradiction between signal quality and power consumption.
Solution Approach 2:
The patent introduces an intermediary element - the lookup table storing pre-calculated amplitude information - between the input signal and the delta-sigma modulation process. This intermediary allows the system to avoid direct quantization of rapidly varying amplitude signals, thereby eliminating the need for steep filters while maintaining signal quality. The lookup table acts as a buffer that mediates the transformation process.
2Measurement precision
If conventional transmission circuits use steep filter characteristics to remove quantization noise, then signal quality is improved, but circuit size increases
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing amplitude information in a lookup table before delta-sigma modulation. The amplitude calculation section computes amplitude values in advance and stores them, so that during modulation the stored values are directly used without requiring steep filters. This preliminary preparation eliminates quantization noise at its source, resolving the contradiction between signal quality and circuit size.
Solution Approach 2:
The patent introduces an intermediary element - the lookup table storing pre-calculated amplitude information - between the input signal and the delta-sigma modulation process. This intermediary allows the system to avoid direct quantization of rapidly varying amplitude signals, thereby eliminating the need for steep filters while maintaining signal quality. The lookup table acts as a buffer that mediates the transformation process.
3Adaptability or versatility
If delta-sigma modulation is applied to signals with large envelope variation, then modulation capability is improved, but quantization noise increases requiring steep filters
Solution Approach 1:
The patent applies segmentation by dividing the modulation process into two independent parts: amplitude information (stored in lookup table) and phase information (processed by delta-sigma modulation). By segmenting the signal processing, the system can handle large envelope variations through the amplitude table while keeping the modulation section free from quantization noise, thus improving modulation capability without generating harmful noise.
Solution Approach 2:
The patent introduces an intermediary element - the lookup table storing pre-calculated amplitude information - between the input signal and the delta-sigma modulation process. This intermediary allows the system to avoid direct quantization of rapidly varying amplitude signals, thereby eliminating the need for steep filters while maintaining signal quality. The lookup table acts as a buffer that mediates the transformation process.
Data Source
AI summary
Provided is a transmission circuit which is small in size, operates with high efficiency, and outputs a transmission signal having high linearity. A signal generation section 11 generates an amplitude signal m(t) and a phase signal. An angle modulation section 17 angle-modulates the phase signal to output an angle-modulated signal. An amplitude calculation section 12 outputs a discrete value signal V(t) having a plurality of discrete values corresponding to a magnitude of the amplitude signal m(t). A dividing section 13 divides the amplitude signal m(t) by the discrete value signal V(t) to output an amplitude signal M(t). A delta-sigma modulation section 14 delta-sigma modulates the amplitude signal M(t) to output a delta-sigma modulated signal. A variable gain amplifier section 15 amplifies the delta-sigma modulated signal by a gain corresponding to the discrete value signal V(t). An amplitude amplifying section 16 supplies, to an amplitude modulation section 18, a voltage corresponding to a magnitude of the delta-sigma modulated signal. The amplitude modulation section 18 amplitude-modulates the angle-modulated signal by the voltage supplied from the amplitude amplifying section 16, to output a modulation signal.