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Inductively Balanced Power Distribution

IP.com Disclosure Number: IPCOM000050575D
Original Publication Date: 1982-Nov-01
Included in the Prior Art Database: 2005-Feb-10
Document File: 3 page(s) / 58K

Publishing Venue

IBM

Related People

Feder, J: AUTHOR [+2]

Abstract

Adding high inductance structures to balance the inductance of the unregulated inputs provides dispersed regulators with acceptable regulation of power frequencies in the 100 MHz range.

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Inductively Balanced Power Distribution

Adding high inductance structures to balance the inductance of the unregulated inputs provides dispersed regulators with acceptable regulation of power frequencies in the 100 MHz range.

In Josephson junction technology, power frequencies also serve as the master clock, and require careful regulation. The power waveform must be delivered with acceptably small timing skew as well as with satisfactory regulation and duty factor. Regulators are dispersed at the branch ends of a folded tree power distribution network so as to limit the path lengths of the regulated logic circuits; at the power frequencies required, the inductance distribution of the unregulated network affects the currents delivered to the individual regulators.

A "tree" followed by a "string bus" is shown in Fig. 1. The sinusoidal (unregulated) current waveform in introduced at the base of a folded tree, which splits n times, giving 2 electrically equivalent sites at the branch ends. The regulator junctions, which clip the input waveform, are located at these sites. The logic devices connect to the regulators in series strings which run perpendicular to a Long narrow power stripe on the chip. The string arrangement introduces an acceptably small timing skew (tens of ps) due to differences in path lengths to different logic devices.

The unregulated (pre-regulator) distribution network must be inductively balanced. That is, if the regulators were replaced by shorts to ground and DC current were applied to the input of the (now zero-resistance) network, the distribution of inductance in the network must be such that each of the shorting elements would carry the same current. Inductive balance is necessary because the regulator junctions, during the regulated portion of the power cycle, are in a low (typically about 0.01 ohm) dynamic resistance state. At power frequencies in the 100 MHz range, the inductive reactance of even a short (10-20 mil) length of transmission line in the unregulated distribution network is comparable to the regulator resistance. Hence, the inductance distribution of the unregulated network is a major factor in determining the current delivered to the regulators. Balanced current levels requ...