Single-Supply Sampling Circuit for Bipolar Input Voltage Range
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Solution Overview
Problem
Conventional integrated sampling circuits require multiple supply voltages and attenuation resistors to sample real-world signals, leading to increased system noise and complexity, which conflicts with the need for smaller chip geometries and reduced manufacturing costs.
Innovation Solution
A single-supply sampling circuit using bootstrap capacitors and a positive feedback mechanism to sample input signal voltages between a positive and negative voltage range without requiring an external negative supply voltage or attenuation resistors, simplifying driver circuitry and reducing power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple supply voltages are used to sample real-world signals, then the sampling voltage range is extended, but the system complexity and manufacturing cost increase
Solution Approach 1:
The patent changes the voltage parameter by using a single supply voltage VDD but achieving the ability to sample signals ranging from -VDD to +VDD through clever circuit design. The bootstrap capacitors and switching mechanism dynamically generate the required negative voltage swing without requiring a negative power supply, thus extending the sampling voltage range while maintaining single-supply simplicity
Solution Approach 2:
The patent introduces bootstrap capacitors as intermediary energy storage elements that mediate between the single positive supply voltage and the required bidirectional signal sampling. These capacitors temporarily store and release energy to create the negative voltage swing needed for sampling signals below ground potential, eliminating the need for complex multiple supply voltage architecture
2Use of energy by moving object
If attenuation resistors are used to reduce signal voltage, then the voltage level is reduced to supported levels, but the transducer current increases and system noise increases
Solution Approach 1:
The patent replaces the passive resistive attenuation mechanism with an active switching mechanism controlled by bootstrap capacitors. Instead of continuously dissipating signal energy through resistors, the circuit uses transient capacitive coupling to transfer signal energy, thereby eliminating the need for high transducer current and reducing the noise floor associated with resistive loading
3Adaptability or versatility
If multiple supply voltages are used, then the input signal voltage range can be sampled, but the driver circuitry complexity increases
Solution Approach 1:
The patent implements a self-service mechanism where the bootstrap capacitors automatically charge during the non-sampling phase and discharge during the sampling phase to generate the required gate drive voltages. The circuit self-regulates the switching timing and voltage levels without requiring external negative supply voltage or complex driver circuitry, thereby simplifying the overall driver architecture while maintaining full bidirectional sampling capability
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
Enables efficient sampling of input voltages across a wide range with a single supply, reducing system noise and complexity, resulting in smaller, more reliable, and cost-effective designs for applications like analog-to-digital converters.
Implementation Method 1
bootstrap capacitors are pre-charged to the single supply voltage. When in the active sampling state, the bootstrap capacitors are used to turn on the input switches
Data Source
AI summary
In embodiments of the present invention a device, circuit, and method are described for sampling input signal voltages, which may include voltages below a negative supply voltage for the device or circuit, without requiring static current from the input. Various embodiments of the invention obviate the requirement of an external negative supply voltage or attenuation resistors to allow sampling between a positive and negative voltage range. These embodiments result in a lower power sampling solution as well as simplifying any driver circuitry required by the sampler. The embodiments of the invention may be applied to sampling processes within analog-to-digital converters and may also be applicable to various other types of circuits in which a sampling input having input voltages that are lower than its negative supply voltage.