Apparatus and method for digital control systems
AssigneeMotorola, Inc.
InventorsPatrick Joseph Pratt, Dale G Schwent, Thomas D Nagode
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Abstract
An apparatus and method for controlling an output (50) of a digital system (10) comprising, for example, an output of a power amplifier (24) to minimise or neutralise nonlinearities such as limit cycles. The digital system comprises a nonlinearity means or limit cycle suppressor (16) to counter the limit cycle effect by intentionally introducing a second nonlinearity into the system (10) to suppress the limit cycle effect in the digital system (10).
Claims8
An apparatus for controlling an output of a digital system comprising:
- a limit cycle source element for receiving an input signal of the digital system and introducing a first nonlinearity into the system with an error signal having a first effective gain, and a limit cycle suppressor for introducing a second nonlinearity into the system with limit suppressor signal, said second nonlinearity having a second effective gain which is the inverse of the first effective gain to provide an output signal having a composite gain within a predetermined range, wherein the second nonlinearity is selected from within a predetermined range selected from a range of the inverse gain of the first effective gain.
A method for controlling an output of a digital system comprising the steps of:
- receiving an input signal of the digital system at a limit cycle source element introducing a first nonlinearity into the system with an error signal having a first effective gain;
- and
- introducing a second nonlinearity into the system from a limit cycle suppressor with limit suppressor signal, said second nonlinearity having a second effective gain which is the inverse of the first effective gain to provide an output signal having a composite gain within a predetermined range, wherein the second nonlinearity is selected from within a predetermined range dependant from a range of the inverse gain of the first effective gain.
Dependencies are inferred from the claim text.