Browse Prior Art Database

BiCMOS Driver With a Clamped Up Level

IP.com Disclosure Number: IPCOM000103333D
Original Publication Date: 1990-Oct-01
Included in the Prior Art Database: 2005-Mar-17
Document File: 1 page(s) / 36K

Publishing Venue

IBM

Related People

Flaker, RC: AUTHOR [+2]

Abstract

By including a bipolar device wired as a diode in bipolar complementary metal oxide silicon (BICMOS) technology, the up level of an off-chip driver (OCD) circuit is clamped. No standby power is required and overshoot is avoided during fast pull-up of output signals with this clamping method.

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BiCMOS Driver With a Clamped Up Level

      By including a bipolar device wired as a diode in bipolar
complementary metal oxide silicon (BICMOS) technology, the up level
of an off-chip driver (OCD) circuit is clamped.  No standby power is
required and overshoot is avoided during fast pull-up of output
signals with this clamping method.

      Referring to the figure, the driver is selected when address
input 2 goes positive from ground and timing input 4 goes negative
from high supply voltage VH.  Output OUT is triggered by the later of
the two transitions.  The driver is restored by a rising timing pulse
edge at input 4.

      Bipolar NPN devices B1 and B2 are added to a standard CMOS
driver circuit.  Device B2 pulls output OUT up to a voltage level V
determined by diode-coupled device B1.  V = VH - Vbe, where Vbe is
the  base to emitter voltage of device B1.  This provides a fast
transition with no overshoot above V.

      Devices included in the standard circuit are P-type MOS
transistor T1 which is used as a bleeder device, N-type MOS
transistor T2 which is gated by address input 2, and inverter I which
gates N-type MOS transistor T3.

      Disclosed anonymously.