Cascode AM Transmitter Bias Synchronization for Wide Modulation Range
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Solution Overview
Problem
Existing amplitude modulators implemented in an analog manner face challenges with large circuit area and high power consumption, and existing amplitude modulation transmission devices struggle to cover the required modulation index range due to fixed operating parameters.
Innovation Solution
A structure that allows for a wide range of modulation indices by transforming transmission data into sinusoidal wave transitions, applying controlled delays, and synchronizing biases of cascode power amplifiers, using a transmission modulation control unit and cascode power amplifiers with differential configurations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If amplitude modulators are implemented in an analog manner using frequency mixers, then amplitude modulation can be achieved, but the area of the integrated circuit becomes large and power consumption becomes high
Solution Approach 1:
The patent replaces the traditional analog frequency mixer mechanism with a digital signal processing approach. The amplitude modulation is achieved through digital techniques including pulse shaping circuits, digital-to-analog converters, and controlled signal combination, eliminating the need for large-area analog mixing components while reducing power consumption.
Solution Approach 2:
The invention changes the operating parameters and signal forms used in amplitude modulation. Instead of using traditional analog carrier waves and modulating signals, the patent employs digitally generated pulse-shaped signals with specific voltage levels and timing characteristics, allowing compact implementation while achieving the desired modulation effect.
2Device complexity
If a cascode power amplifier is used with a fixed bias configuration, then the circuit structure is simplified, but the modulation index range cannot cover the required values for different countries and service providers
Solution Approach 1:
The patent introduces dynamic control of the bias voltage applied to the cascode power amplifier. By dynamically adjusting the bias level based on the desired modulation index, the system can adapt to different country and service provider requirements while maintaining the simplified cascode structure. The bias control circuit responds to control signals that determine the operating point of the amplifier.
Solution Approach 2:
The invention makes the cascode power amplifier multi-functional by adding control mechanisms that allow it to operate with different modulation indices. The same basic amplifier structure can serve multiple purposes by adjusting the bias control signals, eliminating the need for different hardware configurations for different regulatory requirements.
3Device complexity
If the baseband signal waveform is adjusted only through a bias part, then the circuit is simple, but it cannot achieve voltage levels suitable for common gate amplifier across different operating conditions
Solution Approach 1:
The patent introduces an intermediary pulse shaping circuit between the digital signal source and the common gate amplifier. This circuit includes digital-to-analog converters and signal combination logic that generate the appropriate voltage levels and waveforms. The intermediary circuit translates digital control signals into the required analog voltage levels without requiring complex direct adjustment of the amplifier bias.
Data Source
AI summary
A technology related to a transmission device of an amplitude modulation method is disclosed. In the amplitude modulation transmission device, a transmission data signal transformed into a sinusoidal wave transition form is input to a signal input stage of a cascode power amplifier, and a transmission data signal transformed into another sinusoidal wave transition form is input to a bias power stage of the cascode power amplifier. The transmission data signal transformed into the sinusoidal wave transition form has a sinusoidal wave form in a section in which input data transitions and maintain its previous value in a section in which the input data is maintained.