Shared Biasing Circuit for Low-Noise BiCMOS Preamplifiers
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Solution Overview
Problem
The use of CMOS inverter-based preamplifiers in multi-channel integrated circuits for sensor reading introduces noise due to the integrated voltage regulator, leading to increased power dissipation and reduced energy efficiency, making it challenging to maintain a signal-to-noise ratio comparable to conventional preamplifiers.
Innovation Solution
A biasing device with a shared voltage regulator and reference inverter, common to multiple preamplifiers, is used to reduce noise and power dissipation by distributing the bias current across multiple channels, thereby minimizing the impact on the signal-to-noise ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an integrated voltage regulator is used to bias the CMOS inverter-based preamplifier, then the bias current is controlled and transconductance is fixed, but noise is introduced and power dissipation increases
Solution Approach 1:
The patent merges multiple preamplifier biasing requirements into a single shared voltage regulator. Instead of having separate regulators for each preamplifier, the invention combines the biasing function for multiple preamplifiers into one common regulator, thereby reducing the total noise contribution while maintaining proper bias control for each channel.
Solution Approach 2:
The voltage regulator is designed to serve multiple preamplifiers simultaneously, making it a universal biasing device. This multi-functional approach allows the same regulator to provide bias current to several preamplifier stages, reducing overall system complexity and noise while maintaining individual channel performance.
2Object-generated harmful factors
If the bias current of the voltage regulator is increased to reduce its noise, then the noise contribution decreases, but power dissipation increases
Solution Approach 1:
By combining multiple preamplifier biasing functions into a single voltage regulator, the patent enables the regulator to operate at a higher total current level, which reduces its noise contribution. The noise of the regulator is distributed across multiple channels, achieving lower effective noise per channel without requiring each individual regulator to consume excessive power.
3Reliability
If a voltage regulator is added to control the bias current of the inverter, then the transconductance is fixed and noise characteristics are improved, but the device complexity increases
Solution Approach 1:
The patent reduces device complexity by merging the voltage regulator functionality into a shared component that serves multiple preamplifiers. Instead of adding separate regulator circuits to each preamplifier (which would increase complexity), the invention uses one common regulator for multiple channels, thereby maintaining transconductance control while minimizing the increase in overall circuit complexity.
4Adaptability or versatility
If multiple separate voltage regulators are used for multiple preamplifiers, then each preamplifier has independent bias control, but the total noise and power dissipation increase
Solution Approach 1:
The patent combines multiple independent bias control requirements into a single shared voltage regulator that serves all preamplifiers. This merging approach maintains the ability to control bias for each preamplifier while reducing the total noise contribution, as the noise from one regulator is distributed across multiple channels rather than being replicated in each separate regulator.
Data Source
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AI summary
The device (DISP) has pre-amplifiers (AMP-1) with inverters (INV-1) for each acquisition channel. A single polarization device (POL) is shared by two of the pre-amplifiers. The polarization device comprises a voltage regulator and a reference inverter that is identical to the inverters of the preamplifiers. The polarization device is connected in parallel with the pre-amplifiers, and the regulator is connected in series with an assembly comprising the pre-amplifiers. The inverters are produced on basis of bipolar complementary metal-oxide-semiconductor (BiCMOS).