Programmable MOS Amplifier for Linear dB Gain Control
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Solution Overview
Problem
Conventional MOS amplifiers face complexity in achieving linear adjustment of gain in dB units due to the absence of an exponential characteristic between gate-source voltage and output current, unlike Bipolar-Junction-Transistor (BJT) amplifiers, making it difficult to adjust gain linearly with a controlling signal.
Innovation Solution
A programmable gain MOS amplifier is designed with multiple MOS transistors of varying aspect ratios, where gain providers and tuners adjust the gain by turning on/off MOS transistors, allowing for linear adjustment of gain in dB units through a decoder that translates gain level data into controlling signals for the MOS transistors, enabling precise gain control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If conventional MOS amplifiers use standard MOS transistor characteristics, then the amplifier structure remains simple, but the gain cannot be adjusted linearly in dB units
Solution Approach 1:
The amplifier is divided into multiple parallel MOS transistor branches, each contributing a specific gain component. The total gain is the sum of individual branch gains, allowing linear dB adjustment by selectively activating branches with decoder control signals
Solution Approach 2:
The amplifier transitions from a fixed gain structure to a dynamically adjustable gain structure. MOS transistors are selectively turned on/off based on decoder control signals, enabling real-time gain adjustment in dB units without changing the physical amplifier topology
2Measurement precision
If multiple MOS transistors with different aspect ratios are used to achieve programmable gain, then gain adjustment precision improves, but the number of required components increases
Solution Approach 1:
Multiple MOS transistor branches are merged in parallel configuration, sharing common input and output nodes. This reduces the overall component count compared to cascaded configurations while maintaining precise gain control through selective activation of individual branches
3Adaptability or versatility
If gain is adjusted by changing MOS transistor aspect ratios, then gain control flexibility improves, but manufacturing complexity increases
Solution Approach 1:
The invention changes the operational parameters (on/off state) of existing MOS transistors rather than changing their physical dimensions. This allows gain flexibility through electrical control signals from the decoder, avoiding complex manufacturing processes required for variable aspect ratio transistors
Data Source
AI summary
A programmable gain MOS amplifier is disclosed. The programmable gain MOS amplifier is capable of increasing its programmable gain linearly in dB unit by increasing its gain level data linearly. The programmable gain MOS amplifier includes a plurality of gain providers for providing predetermined gains respectively, and a plurality of gain tuners. Each of the plurality of the gain tuners is disposed for adjusting the predetermined gain from the corresponding gain provider. Each of the gain tuners includes a gain enabling module and a gain decreasing module. The gain enabling module allows the corresponding predetermined gain to add to the programmable gain of the MOS amplifier. The gain decreasing module declines the corresponding predetermined gain added to the programmable gain of the MOS amplifier.