PLL Charge Pump Glitch Compensation Without Op-Amp Overhead
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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 techniques 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 a phase compensation capacitor and operational amplifier.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional glitch compensation techniques using operational amplifier and phase compensation capacitor are employed, then glitches are suppressed, but on-die area and production costs increase
Solution Approach 1:
The invention extracts and eliminates the need for the operational amplifier and phase compensation capacitor from the glitch compensation circuit. By using a different approach based on voltage comparison and selective capacitor charging/discharging, the harmful glitches are suppressed without requiring the large on-die area components that conventional techniques demand.
Solution Approach 2:
The invention replaces expensive, large-area components (operational amplifier and phase compensation capacitor) with simpler, smaller components that achieve the same glitch suppression function. The new circuit uses basic voltage comparison and selective capacitor control to achieve glitch-free operation at reduced cost and area.
2Object-affected harmful factors
If conventional glitch compensation techniques using operational amplifier are employed, then glitches are suppressed, but power consumption increases
Solution Approach 1:
The invention removes the operational amplifier from the glitch compensation circuit, eliminating its continuous power consumption. The new approach uses voltage comparators and selective capacitor charging/discharging operations that consume power only when needed, rather than requiring continuous operation of high-power analog components.
Solution Approach 2:
Instead of continuous operation of operational amplifiers, the invention employs periodic or event-driven capacitor charging and discharging based on voltage comparison results. This periodic action ensures glitches are suppressed only when necessary, significantly reducing average power consumption compared to continuously operating analog compensation circuits.
3Object-affected harmful factors
If conventional glitch compensation techniques are employed, then glitches are suppressed, but device complexity increases
Solution Approach 1:
The invention extracts and removes the complex operational amplifier and phase compensation capacitor from the circuit. The simplified approach uses basic voltage comparators, latch circuits, and selective capacitor control to achieve glitch suppression with significantly reduced circuit complexity and fewer interconnections.
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 on-die area and production costs, while minimizing power consumption by selectively performing charging/discharging operations only when necessary, effectively suppressing glitches and improving PLL performance.
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
AI summary
A charge pump circuit (31), and a PLL circuit using the charge pump circuit, has 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) compares potentials and applies a logic output signal to the latch circuit (38), and the latch circuit (38) in response to output of the comparator, instructs 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.