Dual-Output Charge Pump for MEMS Biasing
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Solution Overview
Problem
High area costs are associated with implementing two separate high voltage charge pumps for biasing double backplate or double membrane micro-electro-mechanical systems (MEMS) devices to achieve a sufficient signal-to-noise ratio.
Innovation Solution
A flexible high voltage charge pump design that includes an input charge pump section and two output charge pump sections, where the input charge pump cells generate both output voltages, reducing area costs and allowing for adjustable voltage amplitudes through programmable switches and clock signals, and avoiding leakage current with non-overlapping clock signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If two separate high voltage charge pumps are used to bias each plate individually, then the signal-to-noise ratio is sufficient, but the area costs are high
Solution Approach 1:
The patent combines two separate charge pump functions into a single integrated charge pump device that generates both first and second output voltages. The input charge pump section shares common input nodes and generates multiple output voltages through coupled output charge pump sections, thereby reducing the total area required while maintaining the capability to individually bias both plates for sufficient signal-to-noise ratio
Solution Approach 2:
The single charge pump device is designed to perform multiple functions by generating different output voltages (first output voltage and second output voltage) from a common input. The charge pump can individually bias different plates or membranes, providing universal biasing capability that replaces what would traditionally require two separate charge pump devices
2Adaptability or versatility
If the number of active charge pump cells is increased to adjust output voltage amplitude, then the voltage adjustment flexibility is improved, but the device complexity increases
Solution Approach 1:
The charge pump incorporates a controllable number of active charge pump cells that can be dynamically adjusted to change the output voltage amplitude. This dynamic configuration allows the same charge pump structure to adapt to different voltage requirements without requiring multiple fixed-configuration charge pumps, thereby improving versatility while managing complexity through a unified controllable architecture
Solution Approach 2:
The output voltage amplitude is adjusted by changing the number of active charge pump cells in the charging path. By varying this parameter (number of active cells), the charge pump can provide different voltage levels without altering the fundamental device structure, achieving flexibility through parameter modulation rather than structural multiplication
Data Source
AI summary
A charge pump having an input section, and first and second output charge pump sections. The input section includes an input and output node and N input charge pump cells arranged between the input and output nodes. The first output charge pump section includes a first input and output node and M first charge pump cells arranged between the first input and output nodes. The second output charge pump section includes a second input and output node and K second charge pump cells arranged between the second input and output nodes (M, N, K: any integer≥1). The output node of the input charge pump section is coupled with the first input node of the first output charge pump section and with the second input node of the second output charge pump section. The charge pump is configured to provide a first output voltage on the first output node and a second output voltage on the second output node.