Clock Oscillator Circuit With Shared Charge-Discharge Current Path
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Solution Overview
Problem
Existing oscillator circuits require a large number of circuit components, leading to high power consumption and unacceptable silicon overhead in generating clock signals.
Innovation Solution
The proposed oscillator circuit employs a charge current source, voltage reference sources, and multiplexers to control the charging and discharging of capacitors, using a comparator to switch between charge and discharge nodes, thereby reducing the number of components required.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If prior art oscillator circuits use constant current sources and current mirrors to control capacitor charging and discharging, then the clock signal frequency can be controlled, but the number of circuit components increases leading to high power consumption and large silicon overhead
Solution Approach 1:
The patent combines the constant current source and current mirror functions into a single integrated circuit block. The oscillator circuit uses one constant current source that is shared between charging and discharging operations, eliminating the need for separate current mirrors for each operation. This merging reduces the total number of transistors and circuit components while maintaining the ability to control clock signal frequency through capacitor charging and discharging cycles.
Solution Approach 2:
The patent implements a universal constant current source that serves multiple functions: it provides charge current during capacitor charging phases and discharge current during capacitor discharging phases. The circuit uses control signals to switch the current source between different operational modes, allowing a single component to replace what would traditionally require multiple specialized components. This multi-functionality directly reduces silicon overhead and power consumption.
2Manufacturing precision
If prior art oscillator circuits use separate constant current sources and current mirrors for charging and discharging, then precise frequency control is achieved, but silicon overhead becomes unacceptable
Solution Approach 1:
The patent merges separate charging and discharging current control circuits into a single integrated constant current source with switchable modes. This consolidation maintains precise frequency control through controlled capacitor charging and discharging while reducing the silicon area occupied by current mirrors and associated transistors. The unified design eliminates redundant circuitry that would otherwise be required for separate charging and discharging operations.
Solution Approach 2:
The patent changes the operational parameters of a single constant current source dynamically through control signals. The current source switches between different current magnitudes and directions (charging vs. discharging) based on oscillator phase signals, achieving precise frequency control without requiring multiple fixed-parameter current sources. This parameter switching approach maintains control precision while minimizing silicon overhead.
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 configuration allows for the generation of clock signals with reduced power consumption and silicon overhead, achieving efficient operation with fewer circuit components.
Implementation Method 1
detecting when a voltage on an electrode of the capacitor has risen to or dropped to a threshold value
Implementation Method 2
charging and discharging of one or more capacitors primarily determines the frequency of the clock signal provided by an oscillator circuit
Data Source
AI summary
An oscillator circuit includes a charge current source and first and second muxes. The first mux has a common node, a discharge node, a control node and a charge node coupled to the charge current source. The control node couples the common node to either the discharge or charge nodes. The second mux has a shared node, a reference node, a control node and a ground node coupled to ground. The second mux control node couples the shared node to either the reference or ground nodes. A capacitor is coupled between the common node and the shared node. A comparator has a non-inverting input coupled to the common node, an inverting input coupled to the reference node, and an output coupled to the first and second control nodes. A discharge current sink couples the discharge node to ground and an oscillator output is provided by the comparator.