Feedforward FVF Voltage Regulator for Fast Transient Stability
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Solution Overview
Problem
Existing voltage regulators for integrated circuits struggle to maintain stable output voltage in the face of fast voltage transients and electromagnetic interference (EMI) in harsh automotive environments.
Innovation Solution
A voltage regulator design incorporating a feedforward Wilson current mirror and a flipped voltage follower (FVF) with a super source follower (SSF) loop, which generates a compensation current to stabilize the output voltage and suppress transients.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional voltage regulator designs are used, then the circuit complexity is low, but the output voltage becomes unstable in response to fast voltage transients and EMI
Solution Approach 1:
The voltage regulator is divided into functionally independent modules: a flipped voltage follower (FVF) stage for high-speed transient response, a Wilson current mirror for precise current regulation, and a feedforward capacitor for EMI suppression. Each module operates semi-independently to address specific aspects of voltage stability without requiring complete redesign of the entire circuit.
Solution Approach 2:
The feedforward capacitor is pre-charged to anticipate and counteract voltage transients before they affect the output. The FVF stage is configured to respond preemptively to supply voltage variations, moving a pole at the gate of the pass transistor to maintain stability before transients can propagate through the circuit.
2Reliability
If the regulator responds to fast voltage transients, then the output voltage stability improves, but the quiescent current consumption increases
Solution Approach 1:
The regulator employs dynamic circuit elements including the feedforward capacitor that charges and discharges in response to transient conditions, and the FVF stage that adjusts its operation based on supply voltage variations. These dynamic components enable fast transient response only when needed, rather than continuously consuming high current.
Solution Approach 2:
The circuit parameters such as capacitor values and transistor dimensions are optimized to achieve the desired transient response characteristics while minimizing quiescent current. The feedforward capacitor's capacitance and the FVF transistor sizes are specifically chosen to provide adequate transient suppression without excessive static power consumption.
Data Source
AI summary
A voltage regulator for outputting a regulated output voltage to an integrated circuit, the voltage regulator comprising: a voltage supply terminal for receiving a supply voltage; an output terminal for outputting the regulated output voltage; a reference terminal; a feedforward Wilson current mirror comprising: a Wilson current mirror with an input current terminal and an output current terminal; an input current source coupled between the supply voltage terminal and the input current terminal of the Wilson current mirror; a feedforward capacitor arranged in parallel with the input current source; and an output current transistor with a conduction channel coupled between the supply voltage terminal and the output current terminal of the Wilson current mirror; and a flipped voltage follower, FVF, comprising: a pass transistor comprising a conduction channel coupled between the supply voltage terminal and the output terminal; a first FVF transistor with a conduction channel coupled between the output voltage and a FVF node; a second FVF transistor with a conduction channel coupled between a gate of the pass transistor and the FVF node; a third FVF transistor with a conduction channel coupled between the supply voltage terminal and the gate of the pass transistor, wherein a gate of the third FVF transistor is coupled to a gate of the output current transistor; and a FVF current source coupled between the FVF node and the reference terminal.