Clockless Signal Processing Circuit for Offset-Accurate Charge Transfer
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Solution Overview
Problem
Switched capacitor circuits require a clock to operate, limiting their functionality and introducing offset voltage errors that need separate compensation phases, which can be time-consuming and inaccurate.
Innovation Solution
A signal processing circuit design that eliminates the need for clocks by using amplifier units, capacitors, and single-throw switches connected to a reset signal, allowing immediate calculation and propagation of input signals without clock-mediated charge transfer, thus avoiding offset voltage issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If switched capacitor circuits use clock-mediated charge transfer, then signal processing functionality is achieved, but offset voltage errors are introduced and circuit complexity increases
Solution Approach 1:
The patent extracts and removes the clock mechanism from the switched capacitor circuit, replacing it with a direct charge transfer mechanism using operational amplifiers and capacitors. This eliminates the clock-mediated synchronization requirement and the associated offset voltage errors, while maintaining the signal processing functionality through direct charge redistribution among capacitors in the network.
Solution Approach 2:
The patent introduces operational amplifiers as intermediary elements that directly manage charge transfer between capacitors without requiring clock signals. The op-amps act as mediators that enforce Kirchhoff's laws and enable precise charge redistribution, replacing the clock's synchronizing role with continuous voltage-based control.
2Productivity
If clock signals are used to synchronize switch positions, then charge transfer is controlled, but offset voltage errors accumulate and require separate compensation phases
Solution Approach 1:
The patent implements continuous charge transfer and processing operations without periodic clock interruptions. The operational amplifiers continuously maintain virtual ground conditions and enable ongoing charge redistribution among capacitors, eliminating the need for separate compensation phases and allowing uninterrupted signal processing with continuous correction of any offset errors.
3Adaptability or versatility
If multiple clock signals control different switch categories, then complex signal processing operations are enabled, but circuit complexity and timing requirements increase
Solution Approach 1:
The patent employs a universal operational amplifier-based control mechanism that handles all charge transfer operations without requiring multiple specialized clock signals. The op-amps provide a unified approach to managing charge redistribution across different capacitor groups, enabling complex signal processing operations including FFT through a single integrated control system rather than multiple independent clocked switch networks.
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 immediate calculation of results without clock mediation, reducing sensitivity to offset voltages and allowing complex operations like fast Fourier transforms with improved accuracy and efficiency.
Implementation Method 1
a first capacitor having a first end connected to the inverting input of the first amplifier and a second end connected to the output of the first amplifier
Implementation Method 2
a first amplifier having a non-inverting input, an inverting input and an output, the non-inverting input connected to a ground
Implementation Method 3
a first single-throw switch connected to a reset signal and configured to be in either an open position or a closed position based upon the reset signal
Data Source
AI summary
A signal processing circuit that achieves functionality similar to that of a switched capacitor circuit without the necessity a clock. The circuit compensates for finite open loop gain and for offset voltages in the components, allowing the circuit to “calculate” the result of a problem represented by the circuit essentially immediately upon the presentation of a new input or set of inputs. After the circuit is initialized to remove gain, an input is applied to the circuit, and propagates through the network and affects the state of amplifier outputs; the propagation from the input through capacitors to the ultimate output(s) of the circuit is the analog calculation taking place. The calculation is not mediated by a clock, but rather the calculation corresponds to the circuit's one-time response to the application of the inputs. Using these techniques complex signal processing circuits and even analog neural networks may be constructed.