ADC Input Stage Using Transistor Capacitance for Buffer-Free Conversion
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Solution Overview
Problem
Conventional analog-to-digital converter circuits require a pre-amplification buffer to convert single-ended signals into differential signals, consuming power and area, especially in integrated circuits.
Innovation Solution
A single-ended analog-to-digital converter input stage using transistor-based capacitance, such as CMOS transistors, passively converts single-ended signals into differential signals without additional power, operating in the charge domain and reducing capacitance to minimize noise sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a pre-amplification buffer is used to convert single-ended signals into differential signals, then the signal conversion is achieved, but power consumption and circuit area increase
Solution Approach 1:
The patent extracts and eliminates the pre-amplification buffer from the conventional ADC input stage, directly connecting the single-ended signal source to the differential input stage. This removal of the unnecessary component reduces power consumption and circuit area while the differential input stage inherently handles the signal conversion function through its cross-coupled transistor architecture
Solution Approach 2:
The differential input stage is designed to perform multiple functions simultaneously: it directly accepts single-ended signals, performs differential signal generation, and provides the required voltage level shifting. This multi-functional design eliminates the need for separate pre-amplification buffers, reducing overall power consumption and circuit complexity
2Ease of operation
If a pre-amplification buffer is used to convert single-ended signals into differential signals, then the signal conversion is achieved, but circuit area increases
Solution Approach 1:
The patent removes the pre-amplification buffer component from the circuit architecture, eliminating the area it would occupy. The differential input stage is designed to directly handle single-ended to differential signal conversion without requiring additional buffer circuitry, thus reducing overall circuit area
Solution Approach 2:
The patent merges the signal conversion function with the differential input stage itself. The cross-coupled transistor pair in the differential input stage performs both the differential signal generation and the initial signal conditioning, combining multiple functions into a single integrated structure that occupies less area than separate buffer and input stage components
3Object-affected harmful factors
If the input stage operates in the charge domain with reduced capacitance, then noise sensitivity is reduced, but the circuit requires precise charge management
Solution Approach 1:
The patent changes the operating domain from voltage to charge, and dynamically adjusts capacitance values during the conversion process. By reducing capacitance during the conversion phase, the circuit achieves lower noise sensitivity while the successive approximation mechanism manages charge distribution through a series of controlled switching operations
Solution Approach 2:
The patent employs periodic switching actions through the successive approximation process. The conversion occurs in discrete steps with controlled switching of capacitors and transistors at specific time intervals, allowing precise charge management through rhythmic, predictable operations rather than continuous complex control
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
The solution achieves low-power, high-speed conversion with reduced noise sensitivity by eliminating the need for pre-amplifiers, thus optimizing power and area usage.
Implementation Method 1
analog-to-digital converter circuitry described herein is configured with an input stage that has various advantages over these conventional designs. First, the input stage of various analog-to-digital converter circuits described herein may be configured to passively (without using additional power) and quickly convert a single-ended input signal into a differential signal
Implementation Method 2
the input stage operates in the charge domain (such that charge, rather than voltage, is the quantity conserved and analyzed) and reduces the capacitance during the conversion procedure so as to provide a voltage boost that helps make the circuit less sensitive to noise
Data Source
AI summary
An illustrative input stage for an analog-to-digital converter circuit is described herein. The input stage may include a first transistor of a first conductivity type connected between a first node and a second node; a second transistor of a second conductivity type connected between the first node and a third node; and a set of switches. The set of switches may be configured, when manipulated by a controller, to connect the first node to either an input node or a first output node, the second node to either a first reference node or a second output node, and the third node to either a second reference node or the second output node. Corresponding analog-to-digital conversion circuits and procedures making use of this input stage, as well as corresponding systems, circuitry, and methods, are also disclosed.