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Temperature and Parameter Dependent Voltage Supply for Charge Buffered Logic Circuits

IP.com Disclosure Number: IPCOM000034813D
Original Publication Date: 1989-Apr-01
Included in the Prior Art Database: 2005-Jan-27
Document File: 4 page(s) / 72K

Publishing Venue

IBM

Related People

Wendel, DF: AUTHOR [+2]

Abstract

A technique is described whereby the internal voltage swing, and therefore the speed of charge buffered logic circuits, is maintained over a large temperature and parameter range through the use of voltage supply reference cells and distribution networks. (Image Omitted) A typical charged buffered logic (CBL) circuit, as shown in Fig. 1, is designed to achieve bipolar speed with CMOS compatible power. In the CBL circuit, the internal (base node) swing depends only on the power supply voltage and the VBE voltages of the NPN and PNP transistors. The uplevel of the internal base node (gate is on) is determined by the VBE1 of the NPN. The downlevel is determined by VB minus the VBE2 of the PNP transistor.

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Temperature and Parameter Dependent Voltage Supply for Charge Buffered Logic Circuits

A technique is described whereby the internal voltage swing, and therefore the speed of charge buffered logic circuits, is maintained over a large temperature and parameter range through the use of voltage supply reference cells and distribution networks.

(Image Omitted)

A typical charged buffered logic (CBL) circuit, as shown in Fig. 1, is designed to achieve bipolar speed with CMOS compatible power. In the CBL circuit, the internal (base node) swing depends only on the power supply voltage and the VBE voltages of the NPN and PNP transistors. The uplevel of the internal base node (gate is on) is determined by the VBE1 of the NPN.

The downlevel is determined by VB minus the VBE2 of the PNP transistor. Since the circuits are normally used in the 10o to 100oC temperature range, the VBE of the switching transistor varies approximately 180 mV (2mV/oC) over the entire temperature range. The internal voltage swing (2VBE-VB11) depends on two VBE voltages. Therefore, the voltage variation can be 360 mV during a temperature change from 10o to 100oC. Consequently, the internal voltage swing must be large enough to tolerate this variation. In addition, the VBE itself can vary, due to process parameter and current tolerences, as well as variations in power supply tolerences. The concept described herein provides a voltage supply reference that will compensate for the temperature and parameter tolerence variations. The concept differs from prior-art voltage supplies, in that the voltage is controlled in such a way that the selected internal swing is kept constant. This provides a means of stabilizing the speed of the circuit. Fig. 2 illustrates the dependence of the delay of the CBL circuit on the internal swing. Without implementing the concept described herein, an internal swing of approximately 500 mV would be necessary. However, by implementing the voltage reference control circuit, the swing can be kept at approxima...