On-Die Regulator PSRR Measurement Circuit for Wideband Debug
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Solution Overview
Problem
Conventional methods and circuits struggle to accurately measure and debug the power supply rejection ratio (PSRR) of on-die regulators over a wide frequency range and under high load current conditions.
Innovation Solution
A circuit comprising a filter, a first regulator, and a second regulator is used for PSRR measurement. The filter combines AC and DC input signals, and the regulators adjust output signals based on these inputs, allowing for the separation and measurement of AC and DC components. This configuration enables the calculation of PSRR across a wide frequency range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional measurement methods are used, then the measurement circuit is simple, but the measurement precision is insufficient for wide-frequency range and high load current conditions
Solution Approach 1:
The measurement circuit is segmented into multiple functional blocks: a signal generator block that produces test signals, a device under test block that contains the regulator being measured, and a measurement block that captures output signals. This segmentation allows each block to be optimized for its specific function, improving overall measurement precision while keeping individual blocks manageable in complexity
Solution Approach 2:
An intermediary measurement circuit is introduced between the device under test and the measurement instrument. This intermediary circuit includes buffer amplifiers and signal conditioning components that isolate the DUT from measurement loading effects, enabling accurate PSRR measurement across wide frequency ranges without directly complicating the core measurement methodology
2Adaptability or versatility
If on-die regulator PSRR measurement is implemented, then the measurement can be performed on-chip, but the design complexity increases
Solution Approach 1:
The on-die measurement circuit is designed with universal components that can measure PSRR for different regulator designs and configurations. The measurement block uses generic buffer amplifiers and signal processing circuits that work across multiple DUT variations, enabling on-die measurement capability without requiring custom-designed measurement circuits for each regulator type, thus controlling design complexity
Solution Approach 2:
The measurement circuit is nested within the same die as the device under test. The signal generator, DUT, and measurement block are all integrated on the same chip, with the measurement circuit physically nested around or adjacent to the DUT. This nesting enables on-chip PSRR measurement while sharing common process variations and reducing the need for external components
3Reliability
If high load current measurement is performed, then the PSRR measurement covers practical operating conditions, but the measurement difficulty increases
Solution Approach 1:
The measurement circuit incorporates feedback mechanisms where the output signal from the DUT under high load conditions is fed back through buffer amplifiers to the measurement instrument. The feedback path includes signal conditioning that compensates for loading effects and maintains measurement accuracy even when the DUT is operating at high load currents, making reliable PSRR measurement possible under practical operating conditions
Data Source
AI summary
A circuit for parameter PSRR measurement includes a filter, a first regulator and a second regulator. The filter may be configured for receiving an AC input signal and a DC input signal, and for outputting a combined output signal according to the AC input signal and the DC input signal. The first regulator may be configured for receiving the combined output signal, and for outputting a first output signal having a first AC component signal and a first DC component signal. The second regulator may be configured for receiving the first output signal, and for outputting a second output signal having a second AC component signal and a second DC component signal. A parameter PSRR of the second regulator may be obtained according to a ratio between the second AC component signal and the first AC component signal.