Linear Technology Corporation

Edward Lloyd Henderson

David B Bell

Samuel Hodson Nork

Mark Robert Vitunic

Novel circuitry and methodology are provided for correcting the offset associated with a voltage-controlled current source. An offset correction circuit is coupled to the current source to prevent the output current produced by the current source from deviating from a desired level. The current source may include a transconductance amplifier or a chopper amplifier, and may be configured to produce a zero or non-zero value of the output current.

Offset correction circuit for voltage-controlled current source

The present invention provides radio frequency (RF) power controllers that regulate the power output signal of an RF power amplifier using a control signal. The RF power controller includes a power control amplifier that measures the difference between a feedback signal and a power control input signal to supply the control signal to the RF power amplifier. The output power signal is amplitude modulated for a period of time during an enable mode. During the amplitude modulation period, the RF power controller opens the power control loop and maintains a substantially constant output voltage to the RF power amplifier using a second amplifier and a capacitor coupled to power control amplifier. The capacitor is decoupled from the power control amplifier during the amplitude modulation period, and the second amplifier supplies the output voltage of the RF power controller based upon the stored voltage on the capacitor.

Power controllers for amplitude modulation

The invention provides RF power controllers that cancel offset voltages in the power control loop and external offset voltages by coupling the output of the RF power controller to an auto-zero amplifier during STANDBY mode. The auto-zero amplifier controls the output voltage of the RF power controller during each STANDBY mode so as to eliminate the effect of offset voltages. The voltage at the input of the auto-zero amplifier that allows the offset voltages to be canceled is stored during ENABLE mode. The stored voltage is used by the auto-zero amplifier to continue to remove the effect of the offset voltages on the output voltage of the RF power controller during ENABLE mode. Offset drifts due to temperature, power supply changes, etc. are canceled due to frequent offset sampling.

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Atkinson, NH, United States of America

Edward Lloyd Henderson