Capacitive Coupled Input Transfer Gates for Precision Amplifiers
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Solution Overview
Problem
Precision operational amplifiers face challenges in shifting clock signals from a low voltage reference level to a higher common mode input voltage level without altering the attributes such as amplitude, frequency, and edge characteristics, which is crucial for proper operation in chopper or auto-zero architectures, especially when the power supply voltage is significantly lower than the input voltage.
Innovation Solution
The solution involves using shift circuits with capacitors and Schottky diodes to generate output clocks that maintain the frequency and rise time of the input clock, while adjusting the voltage levels to match the common mode input voltage, using a first shift circuit to produce a clock with a low state corresponding to the input voltage and a second shift circuit to produce a clock with a high state corresponding to the sum or difference of the input and power supply voltages, thereby enabling control of input transfer gates effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional voltage shifting methods are used to shift clock signals from low voltage to high common mode input voltage level, then voltage level shifting is achieved, but signal attributes such as amplitude, frequency, and edge characteristics are altered
Solution Approach 1:
The patent uses capacitors as intermediary elements to transfer clock signals between different voltage domains. The capacitors couple the low-voltage clock signal to the high-voltage domain without direct electrical connection, preserving signal attributes while enabling voltage level shifting. This intermediary approach avoids the signal degradation associated with conventional direct shifting methods.
Solution Approach 2:
The voltage shifting function is divided into separate stages: first, capacitors perform the actual signal coupling and voltage domain translation; second, level shifters adjust the voltage levels of the clock signals to appropriate ranges for controlling input transfer gates. This segmentation allows each component to optimize its function while preserving overall signal integrity.
2Ease of operation
If level shifters are used to adjust clock signal voltage levels to match common mode input voltage, then proper gate control is enabled, but current consumption increases
Solution Approach 1:
The level shifters are activated periodically rather than continuously, operating only during specific phases of the chopper or auto-zero architecture cycle. This periodic activation reduces average current consumption while still providing the necessary voltage level adjustment for gate control during critical operation windows.
Solution Approach 2:
The level shifters dynamically adjust their output voltage parameters based on the operating phase and requirements. By changing voltage levels adaptively rather than maintaining fixed high levels, the circuit achieves proper gate control capability while minimizing energy consumption during non-critical periods.
3Device complexity
If simple voltage shifting is implemented without preserving signal attributes, then circuit complexity is reduced, but operational amplifier precision and reliability deteriorate
Solution Approach 1:
Capacitors serve as intermediary coupling elements that transfer clock signals between voltage domains while preserving signal waveform characteristics. This approach maintains signal attributes such as frequency and edge characteristics without requiring complex active compensation circuits, achieving a balance between simplicity and precision.
Solution Approach 2:
The patent replaces complex active voltage shifting circuits with passive capacitor-based coupling mechanisms. This substitution simplifies the circuit architecture while maintaining signal integrity, as the passive capacitors naturally preserve signal attributes without requiring complex control logic or active compensation elements.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach allows for precise shifting of clock signals to control input transfer gates without significant changes in attributes, enabling reliable operation across different voltage domains and minimizing current consumption, thus improving the reliability and efficiency of precision amplifiers in high-voltage applications.
Implementation Method 1
a first shift circuit coupled to the first input and the third input, and configured to output a first output clock, the first output clock having a low state corresponding to the input voltage
Implementation Method 2
The solution involves using shift circuits with capacitors and Schottky diodes to generate output clocks that maintain the frequency and rise time of the input clock
Data Source
AI summary
According to one embodiment, an apparatus is for use with a remote circuit. The apparatus has a first input for receiving an input voltage, a second input for receiving a power supply voltage, and a third input for receiving an input clock having a high state corresponding to the power supply voltage and a low state corresponding to a return for the power supply voltage. The apparatus includes a first shift circuit coupled to the first input and the third input, and configured to output a first output clock, the first output clock having a low state corresponding to the input voltage. The apparatus further includes a second shift circuit coupled to the first input and the first shift circuit, and configured to output a second output clock, the second output clock having a high state corresponding to the input voltage.