Shared Comparator for Charge Pump Stack-Node Voltage Measurement
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Solution Overview
Problem
Conventional charge pump circuits consume valuable IC area due to the need for multiple measurement circuits, especially in high conversion gain and multi-phase designs, which is a challenge in the trend towards smaller integrated circuits with increased circuitry density.
Innovation Solution
The proposed solution involves a power converter circuit architecture that uses a set of series switches, voltage scaling circuits, multiplexors, and shared comparator circuits to measure voltages at stack-nodes, reducing the number of comparator circuits required and conserving IC area while maintaining efficient measurement capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple measurement circuits are used in charge pump circuits, then voltage measurement accuracy is improved, but IC area consumption increases
Solution Approach 1:
The patent merges multiple measurement functions into a single shared comparator circuit. The comparator is time-multiplexed to sequentially measure voltages at different stack nodes (VC1, VC2, VC3) that would traditionally require separate comparators. This consolidation maintains measurement accuracy while significantly reducing the number of comparators needed from multiple to just one.
Solution Approach 2:
The patent introduces dynamic switching to enable a single static comparator to perform multiple measurement functions. By using switches (S1-S5) controlled by clock signals to dynamically connect different stack nodes to the comparator input, the system achieves the functionality of multiple comparators with a single device, thereby reducing IC area while preserving measurement capabilities.
2Adaptability or versatility
If more measurement circuits are added to high conversion gain and multi-phase charge pumps, then measurement capability is improved, but device complexity increases
Solution Approach 1:
The patent makes the single comparator circuit universal by enabling it to measure voltages at multiple different stack nodes through time-multiplexing. The comparator serves multiple functions by sequentially comparing voltages from VC1, VC2, and VC3 against reference voltages, replacing what would traditionally require multiple dedicated comparator circuits for different measurement points.
Solution Approach 2:
The patent employs periodic switching controlled by clock signals to sequentially connect different stack nodes to the comparator. The switches are toggled at regular intervals to present different voltage inputs to the comparator in a periodic sequence, enabling one comparator to perform the work of multiple comparators through time-based multiplexing.
3Area of stationary object
If a shared comparator is used, then IC area is reduced, but measurement speed may be affected
Solution Approach 1:
The patent performs preliminary voltage comparison actions by continuously monitoring stack node voltages through the switched-capacitor network. The periodic switching and sequential measurement approach allows the system to prepare and capture voltage information at optimal moments in the charge pump cycle, maintaining measurement effectiveness despite the single comparator bottleneck.
Data Source
AI summary
Power converter circuits, including DC-DC converter circuits, that conserve IC area by utilizing more area-efficient alternatives for measurement circuitry. Various embodiments include a power converter circuit including a charge pump having a plurality of stack-nodes VCXM and at least one multiplexor for coupling selected stack-nodes VCXM to a corresponding comparator circuit configured to output a signal indicative of a difference between a selected input to the multiplexor and a reference signal. The number of comparator circuits is less than (N−1)×M, where N is the conversion gain of the power converter circuit (i.e., the number of charge pump stages X plus one), and M is the number of parallel charge pump legs. Related methods include measuring voltages at stack-nodes VCXM in a charge pump, wherein the stack-nodes VCXM are selected by means of a multiplexor and an input to a comparator.