Apparatus and method for breakdown protection of a source follower circuit
AssigneeAgere Systems Inc.
InventorMichael J. Peterson
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Abstract
A breakdown protection circuit for a source follower comprising a field effect transistor (FET). The protection circuit comprises a plurality of PFET's and NFET's that are controlled to exhibit on and off states for advantageously configuring a gate, source, drain and body of the source follower FET, to avoid breakdown of and forward biasing of certain FET junctions.
Claims23
A breakdown protection circuit for a field effect transistor comprising a gate responsive to an input signal supplied to an input terminal, a first source/drain responsive to a power supply voltage, a second source/drain for connecting to an output terminal and a body, the circuit comprising:
- a first switching element for selectably connecting the gate to the input terminal for operation in a source follower mode or to the body for turning the field effect transistor off;
- and
- a second switching element for selectably connecting the gate and body to the power supply when a voltage at the output terminal has a predetermined relation to the power supply voltage or to the output terminal for operation in the source follower mode.
Dependencies are inferred from the claim text.