Browse Prior Art Database

Single Supply Voltage Divider for Small Signal Loads

IP.com Disclosure Number: IPCOM000081907D
Original Publication Date: 1974-Aug-01
Included in the Prior Art Database: 2005-Feb-28
Document File: 2 page(s) / 36K

Publishing Venue

IBM

Related People

Hanna, RW: AUTHOR [+2]

Abstract

The cascode connected array of field-effect transistor (FET) devices will provide a plurality of voltage levels from a single supply, when the divider current is appropriately chosen and the output load is a DC bias level or relatively small signal load. The divider is stabilized from a temperature change by incorporation into the same semiconductor device as the load circuit.

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Single Supply Voltage Divider for Small Signal Loads

The cascode connected array of field-effect transistor (FET) devices will provide a plurality of voltage levels from a single supply, when the divider current is appropriately chosen and the output load is a DC bias level or relatively small signal load. The divider is stabilized from a temperature change by incorporation into the same semiconductor device as the load circuit.

The figure shows a plurality of FET devices 1, 2, 3...N-1,N connected in a cascode configuration between a supply (E(DD)) and a reference (E(SS)) supply. Output voltages V(1), V(2), ...V(n-2), V(n-1) are at levels depending upon device characteristics and biased regions. A divider current of about ten times expected signal output current is required to overcome loading effects. Output voltage levels are obtained as follows: V(1) = E(DD) - V(GS1) (1) I(d1) = gamma m over 2 W over L(eff) (V(GS1) - V(TH))2 (2) where gamma M = Normalized transconductance. V(TH) = Gate threshold voltage. W over L(eff) = Effective width-to-length ration FET 1. V(GS1) = Voltage across gate-source electrodes of FET 1. I(dl) = Drain current of FET 1. W over L(eff) = 2 Idl over gamma m(V(GS1) - V(TH))2 (3).

The output voltages for devices two and three are similarly calculated based on their drain current, normalized transconductance, threshold voltage, effective width-to-length ratio, and the voltage drop across a device between the drain and source electrodes (V(...