Chengming He

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In this paper, the systematic mismatch error in integrated circuits due to gradient effects is modeled and analyzed. Three layout strategies with improved matching performance are reviewed and summarized. The hexagonal tessellation pattern can cancel quadratic gradient errors with only 3 units for each device and has high area-efficiency when extended. Both(More)
This paper discusses systematic mismatch due to gradient in IC fabrication and presents a generic layout strategy to enhance matching characteristics for passive and active devices in VLSI. Circular symmetry pattern, a new type of layout structure, was proposed and its effect on high order gradient cancellation was discussed. Analytical deviations suggested(More)
Analog and mixed-signal test is identified as one of the most daunting challenges for system-on-a-chip design. The bottleneck of mixed-signal test is the instrumentation of high precision signal generators and response measurement devices. This paper provides a cost-effective solution to the mixed-signal test problem by using lowaccuracy but(More)
The bottleneck of linearity test for high-resolution ADCs lies in the design and manufacturing of fast and stationary signal generators with performance much better than the specification of ADCs under test. Recently a cost-effective approach was proposed for precision ADC linearity test using low-linearity but easy-to-generate ramp signals. This approach(More)
An optimal loop parameter design method of charge pump PLLs for jitter transfer characteristic optimization is proposed. Based on the linear model of charge pump PLLs, the relationship between PLLs’ loop parameters and jitter transfer characteristic is illustrated. Using the proposed optimal design method, a design example is done and the expected(More)
For low-voltage, low-power circuit design, the linear model for operational amplifiers is insufficient to accurately predict the static and dynamic behavior of the circuit. This paper introduces a nonlinear model for operational amplifiers based on amplifiers’ DC transfer characteristic. By using this nonlinear model, the behavior of an operational(More)
High gain operational amplifiers are by far the most fundamental building block in analog and mixed-signal design. In the first few chapters, design of high gain CMOS positive feedback amplifiers (PFAs) is studied. A low-voltage positive feedback amplifier in standard digital CMOS with 3 transistors stacked between VDD and VSS is designed and circuit(More)
In this paper, systematic mismatch due to parameter gradients is modeled and analyzed. A new layout strategy with flexible cell placement is proposed. Theoretical analysis shows its property of canceling the mismatch between two devices due to up to n order gradient effects by using 2 unit cells for each device. Simulation results show that the proposed(More)