Charge Pump Glitch Compensation Using Comparator-Latch Control
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Solution Overview
Problem
Conventional charge pump circuits in PLL synthesizers suffer from glitches in current pulses, leading to phase noise deterioration, and existing glitch compensation methods increase production costs and energy consumption.
Innovation Solution
A charge pump circuit with a glitch compensation circuit comprising a comparator, latch circuit, capacitor, and charge/discharge device, which compares potentials and adjusts the capacitor's charge/discharge to minimize potential differences and reduce glitches, thereby eliminating the need for phase compensation capacitors and operational amplifiers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If conventional glitch compensation methods using operational amplifiers and phase compensation capacitors are employed, then glitches in current pulses are reduced, but production costs increase and on-die area expands
Solution Approach 1:
The patent extracts and eliminates the need for operational amplifiers and phase compensation capacitors from the charge pump circuit. By removing these conventional glitch compensation components, the circuit achieves glitch reduction without requiring additional on-die area for these elements, thus resolving the contradiction between glitch reduction and area minimization
Solution Approach 2:
The patent uses a simplified glitch compensation approach that copies only the essential functionality needed for glitch reduction, rather than implementing the full conventional operational amplifier-based compensation circuit. This selective copying achieves the necessary glitch suppression while minimizing the area occupied by compensation components
2Object-generated harmful factors
If conventional glitch compensation methods using operational amplifiers are employed, then glitches in current pulses are reduced, but energy consumption increases
Solution Approach 1:
The patent removes operational amplifiers from the glitch compensation circuitry. Since operational amplifiers are high-power consuming components, their elimination directly reduces the energy consumption of the charge pump circuit while still achieving glitch reduction through the simplified compensation mechanism using basic switches and capacitors
Solution Approach 2:
The patent employs simple, low-power components such as switches and small capacitors for glitch compensation instead of expensive, high-power operational amplifiers. These simpler components consume significantly less energy while providing adequate glitch suppression for the application
3Object-generated harmful factors
If conventional glitch compensation methods are employed, then glitches in current pulses are reduced, but device complexity increases
Solution Approach 1:
The patent extracts and removes the complex operational amplifier-based compensation circuitry from the charge pump design. By eliminating these complex components and replacing them with simple switches and capacitors, the overall circuit complexity is reduced while maintaining glitch suppression functionality
Solution Approach 2:
Instead of adding complex operational amplifiers to compensate for glitches, the patent inverts the approach by using simple switches and capacitors in a novel configuration that achieves glitch reduction without increasing complexity. This inverted approach simplifies the overall circuit architecture
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 reduces glitches in current pulses, decreases production costs by minimizing on-die area, and lowers energy consumption by reducing unnecessary charging/discharging operations, especially in the locked state.
Implementation Method 1
a comparator (37) operable to compare a potential at the first output terminal or a potential at a designated node in a loop filter (4) connected to the first output terminal, with a potential at the second output terminal
Implementation Method 2
a capacitor (C1) connected between the second output terminal and a ground point; and a charge/discharge device operable, in response to an output of the latch circuit, to selectively charge and discharge the capacitor
Data Source
Figure 1
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AI summary
A charge pump circuit 31, and a PLL circuit using the charge pump circuit, according to the present invention, comprises a glitch compensation circuit 36 to compensate for a slow glitch which occurs along charging/discharging of electric charges in a parasitic capacitance. The glitch compensation circuit 36 includes a comparator 37, a latch circuit 38, a capacitor C1 and transistors Q9, Q10 serving as a charge/discharge device. The comparator 37 is operable to compare between given potentials and apply a logic output signal to the latch circuit 38, and the latch circuit 38 is operable, in response to an output of the comparator at a given timing, to instruct the charge/discharge device to perform a charge or discharge operation to charge or discharge the capacitor so as to allow a potential at a second output terminal to come close to a potential at a first output terminal or a potential at a designated node in a loop filter of the PLL circuit.