Chengming He

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—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 th order gradient effects by using 2 n unit cells for each device. Simulation results show that the(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)
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)
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 low-accuracy but(More)
An infinite DC gain CMOS positive feedback amplifier with 90° phase margin was designed and its nonlinear dynamics was studied using level 1 MOS models. Analytical derivations were utilized to investigate its equilibrium point, turning point, stability and branching properties. Analysis suggested this amplifier would show parameter-dependent supercritical(More)
—A CMOS differential positive feedback amplifier (PFA) and its inherent nonlinearity were analyzed. Based on nonlinear dynamical systems and bifurcation theory, we predicted bifurcation and hysteresis phenomena in the PFA. An algorithm, which can be implemented using simple digital logic, was developed to measure the PFA's open-loop stability as the(More)
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