Browse Prior Art Database

Precharge for DC Restore Loop Capacitor in Arm Electronics Chip

IP.com Disclosure Number: IPCOM000119317D
Original Publication Date: 1991-Jan-01
Included in the Prior Art Database: 2005-Apr-01
Document File: 2 page(s) / 56K

Publishing Venue

IBM

Related People

Swart, DP: AUTHOR

Abstract

This article describes use of a resistor divider to precharge the DC restore's loop capacitor before the preamplifier circuit is activated. When the circuit is activated, the divider is disconnected from the loop capacitor by FET switch devices. With this precharge invention, the DC restore loop is ready for operation within a few micro-seconds after the the circuit is activated.

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This is the abbreviated version, containing approximately 68% of the total text.

Precharge for DC Restore Loop Capacitor in Arm Electronics Chip

      This article describes use of a resistor divider to
precharge the DC restore's loop capacitor before the preamplifier
circuit is activated.  When the circuit is activated, the divider is
disconnected from the loop capacitor by FET switch devices.  With
this precharge invention, the DC restore loop is ready for operation
within a few micro-seconds after the the circuit is activated.

      The figure shows the preamplifier with its DC restore loop.
Only the precharge network consisting of resistors 1, 2, 3 and 4, and
FETs 5, 6 and 7 are claimed in this disclosure.

      The DC restore loop consists of Operational Transconductance
Amplifier (OTA) 10, capacitor 11, and the preamplifier front end 14.
Capacitor 11 is the loop's compensation and holding capacitor.

      BEFORE CHIP IS ACTIVATED.  The voltage divider consisting of
resistors 1, 2, 3 and 4 are connected to capacitor 11 before the chip
is activated.  (FETs 5, 6 and 7 are turned on, and have essentially
0.0 volts drop across them.) The voltage drop across resistor 2 is
designed to apply the nominal operating voltage across capacitor 11.

      NFET 21 in current source 20 is off, so current source
transistor 22 is also off, and preamplifier front end 14 is inactive.

      Assuming a long time delay (several seconds) exists between
power-on and circuit activation, the precharge network has ample time
to settle before th...