Translinear Circuits

Gilbert, B.

doi:10.1002/047134608x.w2302

Cited by 2 publications

(1 citation statement)

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“…: : : : : : : : : : : 56 3-14 Typical optical ccd responsivity. : : : : : : : : : : : : : : : : : : : : : : : : : : : 58 3-15 Input structures, clocking waveforms, surface potentials, and signal charge, for (a) the standard ll-and-spill approach and (b) for the split-gate ll-and-spill technique. : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 59 3-16 Potentials and charge locations during shifting and sensing for (a) the oating di usion output structure and (b) the oating gate output structure.…”

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An analog VLSI chip for estimating the focus of expansion

McQuirk

Lee²,

Horn³

1997 IEEE International Solids-State Circuits Conference. Digest of Technical Papers

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For applications involving the control of moving vehicles, the recovery of relative motion between a camera and its environment is of high utility. This thesis describes the design and testing of a real-time analog vlsi chip which estimates the focus of expansion (foe) f r o m measured time-varying images. Our approach assumes a camera moving through a xed world with translational velocity the foe is the projection of the translation vector onto the image plane. This location is the point t o wards which the camera is moving, and other points appear to be expanding outward from. By way of the camera imaging parameters, the location of the foe gives the direction of 3-D translation.The algorithm we use for estimating the foe minimizes the sum of squares of the di erences at every pixel between the observed time variation of brightness and the predicted variation given the assumed position of the foe. This minimization is not straightforward, because the relationship between the brightness derivatives depends on the unknown distance to the surface being imaged. However, image points where brightness is instantaneously constant play a critical role. Ideally, the foe would be at the intersection of the tangents to the iso-brightness contours at these \stationary" points. In practice, brightness derivatives are hard to estimate accurately given that the image is quite noisy. Reliable results can nevertheless be obtained if the image contains many stationary points and the point is found that minimizes the sum of squares of the perpendicular distances from the tangents at the stationary points.The foe chip calculates the gradient of this least-squares minimization sum, and the estimation is performed by closing a feedback loop around it. The chip has been implemented using an embedded ccd imager for image acquisition and a row-parallel processing scheme. A 64 64 version was fabricated in a 2 m ccd/bicmos process through mosis with a design goal of 200 mW of on-chip power, a top frame rate of 1000 frames/second, and a basic accuracy of 5%. A complete experimental system which estimates the foe in real time using real motion and image scenes is demonstrated.

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An analog VLSI chip for estimating the focus of expansion

McQuirk

Lee²,

Horn³

1997 IEEE International Solids-State Circuits Conference. Digest of Technical Papers

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Log-domain filtering and the Bernoulli cell

Drakakis

Payne

Toumazou

1999

IEEE Trans. Circuits Syst. I

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In this paper, the dynamic behavior of a nonlinear circuit element termed a Bernoulli cell is described, which is composed of a suitably biased bipolar junction transistor (BJT) and an emitter connected grounded capacitor. This cell has application in the synthesis of log-domain filters, since it facilitates the development of a low-level design approach in which a frequency-domain transfer function is decomposed into timedomain current product equalities that can be implemented by direct use of the translinear principle (TLP). Furthermore, the dynamic of a log-domain structure can be analyzed and its frequency response can be easily derived when the embedded Bernoulli cells are identified. An analysis and a synthesis example are presented.

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Translinear Circuits

Abstract: The sections in this article are Translinear Cells Translinear Amplifiers Translinear Design Principles

Cited by 2 publications

References 20 publications

An analog VLSI chip for estimating the focus of expansion

An analog VLSI chip for estimating the focus of expansion

Log-domain filtering and the Bernoulli cell

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