Power amplifier protection
AssigneeMarvell International Ltd.
InventorsWayne A. Loeb, Alireza Shirvani-Mahdavi
Life of this patent
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Abstract
A power amplifier protection circuit that includes protection circuitry to variably shunt an input radio frequency (RF) signal to AC ground, turn off bias to an output transistor of a power amplifier, and turn off the output transistor. The power amplifier protection circuit features an asymmetrical control that can quickly shut off a power amplifier, and turn on the power amplifier at a steady, controlled rate when an output transistor exceeds a predetermined threshold voltage.
Claims29
A protection circuit comprising:
- shunt circuitry operable to shunt an RF input signal toward ground, the shunt circuitry including,
- a shunt switch operable to shunt the RF input signal to ground and release the RF input signal from ground, the shunt switch being controlled by control circuitry;
- and
- the control circuitry including ramp circuitry, the ramp circuitry operable to control the shunt switch so that the shunt switch releases the RF signal from ground, the control circuitry including a delay stage so that the shunt circuitry continues to shunt the RF input signal to ground until after an associated circuit has turned back on after a shutdown event;
- and
- bias shutdown circuitry operable to shut off a bias voltage or a bias current being supplied to an output transistor of the associated circuit.
A protection circuit comprising:
- shunting means for shunting an RF input signal to ground and releasing the RF input signal from ground, the shunting means being controlled by control means;
- and
- the control means for controlling the shunting means so that the shunting means releases the RF signal from ground for input to an associated circuit, the control means including a delaying means for delaying a release of the RF input signal until after the associated circuit has turned back on after a shutdown event;
- and
- biasing means for shutting off a bias voltage or a bias current being supplied to an output transistor of the associated circuit.
A method for protecting a circuit from elevated output voltages, the method comprising:
- defining a threshold voltage level for a peak detection;
- detecting an output voltage of a circuit exceeding the threshold voltage level;
- reducing a bias to the circuit when the output voltage exceeds the threshold voltage level;
- and
- separately from reducing the bias circuit, shunting to ground an input of the circuit when the output voltage exceeds the threshold voltage level, until after an output transistor has turned back on.
Dependencies are inferred from the claim text.