Temperature-Compensated Bias Circuit for Stacked Device Amplifiers
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Solution Overview
Problem
Existing bias circuit designs for stacked device amplifiers face challenges in being both process and temperature independent, with open loop designs lacking temperature independence and closed loop designs potentially being unstable and limiting output power and efficiency.
Innovation Solution
An open loop process and temperature independent bias circuit for stacked device amplifiers is developed, utilizing a voltage divider bias module that generates control voltage biases with voltage references proportional to the power supply voltage and an offset voltage term proportional to temperature and process variation, thereby ensuring even power supply division across each device and maintaining performance across varying temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If simple resistive divider biasing networks are used, then the bias circuit is inherently stable with no feedback, but the performance does not exhibit independence from process and temperature variation
Solution Approach 1:
The patent introduces temperature-dependent resistive cells that change their resistance characteristics with temperature to compensate for process and temperature variations. By using resistive cells with specific temperature coefficients, the bias circuit maintains stable voltage division ratios across different operating conditions, achieving both stability and temperature independence simultaneously
Solution Approach 2:
The bias circuit combines multiple resistive cells with different temperature dependencies in a series configuration. This composite structure of resistive elements with complementary temperature characteristics creates a bias network that is both stable and insensitive to temperature and process variations
2Reliability
If closed loop bias circuits with feedback are used, then temperature stability and voltage supply regulation are provided, but the bias networks can be potentially unstable and output power and efficiency are limited
Solution Approach 1:
The patent extracts the feedback mechanism from the bias circuit, transitioning from a closed-loop design to an open-loop design. By removing the feedback path, the circuit eliminates potential stability issues and oscillation problems while maintaining temperature stability through the inherent temperature compensation properties of the resistive cells
Solution Approach 2:
The bias circuit uses self-compensating resistive cells that automatically adjust their voltage division ratios based on temperature changes without requiring external feedback control. The resistive cells inherently track temperature variations and compensate for them, providing self-regulation without the complexity and instability risks of feedback circuits
3Reliability
If closed loop feedback is used, then voltage supply regulation across stacked devices is achieved, but the current of the amplifier is limited at a fixed bias
Solution Approach 1:
By removing the feedback mechanism, the circuit eliminates the current limiting effect that arises from fixed bias conditions in closed-loop designs. The open-loop configuration with temperature-compensated resistive cells allows the amplifier to operate at higher current levels without the stability constraints that would otherwise limit output power
Data Source
AI summary
An open loop process and temperature independent bias circuit for stacked device amplifiers is disclosed herein. In one or more embodiments, a method for biasing a stacked high-voltage signal amplifier with a voltage divider bias module comprises generating, by the voltage divider bias module from a power supply voltage (VDD), a plurality of control voltage biases, which comprise a plurality of voltage references plus an offset voltage term (Vtemp). In one or more embodiments, the plurality of voltage references are each proportional to a division of the power supply voltage (VDD), and the offset voltage term (Vtemp) is proportional to temperature and is a function of process variation. The method further comprises biasing, a plurality of devices of the stacked high-voltage signal amplifier, with the control voltage biases.