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BICMOS Emitter-Coupled Logic Converter for Extended Voltage operation

IP.com Disclosure Number: IPCOM000120123D
Original Publication Date: 1991-Mar-01
Included in the Prior Art Database: 2005-Apr-02
Document File: 2 page(s) / 53K

Publishing Venue

IBM

Related People

Wissel, L: AUTHOR

Abstract

This emitter-coupled logic (ECL) converter, constructed in bipolar complementary metal oxide silicon (BICMOS) technology, is functional with supply voltage VH at a normal operation level and under product burn-in conditions, e.g., with VDD at a higher level.

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BICMOS Emitter-Coupled Logic Converter for Extended Voltage operation

      This emitter-coupled logic (ECL) converter, constructed
in bipolar complementary metal oxide silicon (BICMOS) technology, is
functional with supply voltage VH at a normal operation level and
under product burn-in conditions, e.g., with VDD at a higher level.

      Referring to the figure, mode select signal NT is high for
normal operation and low for burn-in operation.

      In normal operation, emitter follower transistor Q1 having
N-type load transistor T5 provides input signal (Vin - Vbe) to
differential transistor pair Q2 and Q3 through pass gate transistor
pair T1 and T2.  A similar pass gate transistor pair (not shown)
provides an ECL reference signal to Q2 and Q3.  Transistor T0
conducts, effectively shorting out resistor R2, such that transistor
Q3 amplifies the input signal through resistor R1.  Output signal OUT
at collector node C is amplified with respect to ECL levels and is
suitable for a CMOS circuit.

      In extended, or higher voltage, operation, the input signal
retains its level relative to VDD.  The voltage signal on node C from
the circuit, as described in the previous paragraph, is not suitable
for a CMOS circuit because it is too small relative to the greater
VDD of extended operation.  To overcome this limitation, pass gate
transistor pair T3 and T4 supplies the input ECL signal, reduced by
an additional Vbe by diode D1, to differential transistor pai...