Capacitive DAC Gain Switching Without Area Growth
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Solution Overview
Problem
Conventional digital-to-analog converters require a large area due to the need for multiple switches corresponding to divided capacitances, hindering miniaturization and increasing the area required for their formation.
Innovation Solution
A digital-to-analog converter design that uses a plurality of capacitances with switches to switch the second terminal of each capacitance between high and low potential sides based on an input control signal, allowing for gain adjustment and offset adjustment without increasing the area by using a subset of capacitances for voltage generation and gain adjustment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple switches are used to control divided capacitances for gain adjustment, then the voltage value range can be switched, but the area required for the digital-to-analog converter increases
Solution Approach 1:
The patent makes the capacitances multi-functional by enabling them to serve both as voltage generation elements and gain adjustment elements. The same capacitance array is used for different purposes depending on the switching state, eliminating the need for separate components for each function and thereby reducing the overall converter area.
Solution Approach 2:
The patent combines the voltage generation function and gain adjustment function into a single capacitance array controlled by switches. Instead of having separate capacitances for voltage generation and separate switches for gain adjustment, the invention merges these functions into one integrated structure where the same hardware serves multiple purposes.
2Measurement precision
If the number of switches is increased to control each divided capacitance, then the resolution and gain adjustment capability are improved, but the device complexity increases
Solution Approach 1:
The switches are designed to perform multiple functions: they control both the selection of capacitance values for voltage generation and the gain adjustment simultaneously. This multi-functionality reduces the number of independent control signals needed and simplifies the overall control architecture while maintaining high resolution capabilities.
Solution Approach 2:
The patent employs dynamic switching control where the same switch configuration can adapt to different operating modes (different voltage ranges, different gain settings) based on input conditions. This dynamic reconfiguration allows the system to maintain high precision across multiple operating points without requiring dedicated hardware for each mode.
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 enables the formation of a digital-to-analog converter that suppresses area increase while outputting analog signals over a range of voltage values, facilitating miniaturization and efficient signal processing.
Implementation Method 1
a plurality of capacitances C0 to C2 and CA1, that is, a total of five capacitances... each of the capacitances C0 to C2 and CA1... binary weighted capacitances
Data Source
AI summary
A digital-to-analog converter comprising: a plurality of capacitances and a plurality of switches. A capacitance among the plurality of capacitances, of which the number corresponds to the resolution of the analog signal to be output, is used as a voltage value generation capacitance, so as to generate a voltage value based on the reference voltage to be added or subtracted, by switching a node to which the second terminal is connected by a corresponding switch. A remaining capacitance, which is not used as the voltage value generation capacitance among the plurality of capacitances, is used as a gain adjustment capacitance, so as to adjust gain of a voltage value based on the reference voltage to be added or subtracted, by holding a node to which the second terminal is connected by a corresponding switch.