Mitigating Switched Capacitor ADC Load Transient Drift in Integrated References
Mitigating switched-capacitor reference droop requires a low-ESR reservoir capacitor sized to charge-redistribution ratios and Kelvin-connected to analog ground.
Voltage Droop Mitigation
Technique Definition
A corrective design technique in electronic power distribution networks minimizes the amplitude of transient voltage dips during high-current transitions. This voltage droop mitigation ensures that supply lines remain within the specified tolerance of the active components. When digital circuits switch simultaneously, they draw sharp current pulses that can pull down the supply rail.
If left unmanaged, these dips can cause timing errors and data corruption.
Circuit Compensation
Dynamic voltage buffers and active regulators adjust their output impedance to combat sudden current demands. Implementing voltage droop mitigation often involves placing high-speed voltage references and buffers close to the switches. These buffers provide immediate localized current to the switching array.
This localized supply maintains the voltage level before the primary regulator can react.
Decoupling Strategy
Placing a hierarchy of capacitors with varying self-resonant frequencies close to the load provides effective high-frequency decoupling. Small ceramic capacitors handle the fastest transients, while larger tantalum or polymer capacitors sustain the supply voltage during longer load events. This multi-tier approach reduces impedance across a wide frequency spectrum.
Layout Design
Minimizing PCB trace inductance is critical to prevent inductive voltage drops. Wide traces and solid ground planes are used to reduce this impedance.