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FET Device Parameters Compensation Circuit

IP.com Disclosure Number: IPCOM000075936D
Original Publication Date: 1971-Dec-01
Included in the Prior Art Database: 2005-Feb-24
Document File: 2 page(s) / 25K

Publishing Venue

IBM

Related People

Askin, HO: AUTHOR [+3]

Abstract

A given field-effect transistor (FET) circuit can have a wide range of performance and power dissipation because of manufacturing tolerances. Performance and power dissipation are sensitive to device threshold voltage, normalized transconductance, gamma m, and channel width to length ratio, W/L, variations. The present circuit provides compensation for the variations in these parameters due to the manufacturing process.

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FET Device Parameters Compensation Circuit

A given field-effect transistor (FET) circuit can have a wide range of performance and power dissipation because of manufacturing tolerances. Performance and power dissipation are sensitive to device threshold voltage, normalized transconductance, gamma m, and channel width to length ratio, W/L, variations. The present circuit provides compensation for the variations in these parameters due to the manufacturing process.

The compensation circuit consists of several FET diodes 10 in series with a resistor 11, as shown in the figure. If the threshold is low, gamma m and W/L ratio are high, more current will be drawn by the circuit and the output voltage will be lower than the nominal value. If the above three parameters vary in the opposite direction, less current will be drawn by the circuit and the output voltage will be higher than the nominal value. The output of this circuit can be applied to the FET gates of another circuit. The parameters of the two circuits track closely if they are on the same chip. Under low-threshold voltage, high gamma m and high W/L conditions, the FET circuit will tend to dissipate high power. However, the gate supply voltage from the output 12 of the disclosed compensation circuit drops lower under this condition, causing the FET circuit to dissipate less power. The reverse will happen under high threshold, low gamma m and low W/L condition.

The figure shows one application of the compensatio...