Differential Charge Pump Stabilizes Voltage Without Operational Amplifiers
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Solution Overview
Problem
Conventional charge pumps face voltage instability issues due to floating nodes during initialization, requiring additional operational amplifiers for stabilization.
Innovation Solution
A differential charge pump unit with current adjusting devices and a common mode voltage control circuit is introduced, which generates output voltage signals using pump-up and pump-down signals, and provides adjusting currents to maintain stable voltages, reducing the need for additional operational amplifiers and stabilizing common mode voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional charge pump uses operational amplifier to generate feedback control voltage, then voltage control function is achieved, but voltage instability occurs due to floating nodes during initialization
Solution Approach 1:
The charge pump circuit is divided into differential pairs (first and second charge pumps) with separate control paths. Each charge pump has its own control switch and current source, allowing independent control and stabilization of each side, preventing floating node issues while maintaining voltage control functionality.
Solution Approach 2:
Instead of using a single operational amplifier with feedback to control voltage, the invention inverts the approach by using differential current sources that are directly controlled by logic signals. The voltage control is achieved through the differential current balance rather than feedback amplification, eliminating the floating node problem at initialization.
2Reliability
If additional operational amplifier is used to stabilize voltage drop between charge switch and discharge switch, then voltage instability is prevented, but device complexity increases
Solution Approach 1:
The invention extracts the voltage stabilization function from the operational amplifier feedback loop and implements it through the differential current source architecture. By taking out the need for additional operational amplifiers and using purely passive current balancing with differential switches, voltage stability is achieved without adding active stabilization components.
Solution Approach 2:
The differential current sources serve multiple functions: they provide the pump current, establish voltage balance between nodes, and enable initialization without floating conditions. This multi-functionality eliminates the need for separate stabilization operational amplifiers, reducing device complexity while maintaining reliability.
Data Source
AI summary
A differential charge pump includes a differential charge pump unit, current adjusting device, and common mode voltage control circuit. The differential charge pump unit is used for generating a output voltage signal according to a pump-up signal and a pump-down signal. The current adjusting device is coupled to the differential charge pump unit for providing an adjusting current signal to the differential charge pump unit as the pump-up signal and pump-down signal are both enabled or disabled. The control circuit is coupled to the differential charge pump unit for outputting a feedback signal to the differential charge pump unit according to the output voltage signal.