Low current direct conversion transmitter architecture
First Claim
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1. A method, comprising:
- determining a change in a radio frequency transmitter output power;
varying, with a digital variable gain amplifier, a level of an input base band signal at an input of a digital to analog converter that outputs a signal to a radio frequency transmitter chain that comprises a phase modulator of the radio frequency transmitter, where the varying is according to the determined change in the radio frequency transmitter output power, comprising increasing the level of the signal as the radio frequency transmitter output power increases and decreasing the level of the signal as the radio frequency transmitter output power decreases; and
adjusting a bias current of at least the phase modulator according to the varied level of the signal, comprising decreasing the bias current as the level of the signal is decreased and increasing the bias current as the level of the signal is increased.
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Abstract
Disclosed is a method to operate a RF transmitter, and an RF transmitter constructed to operate in accordance with the method. The method includes determining a transmitter output power and varying a level of a signal at a transmitter phase modulator according to the transmitter output power so as to increase the level of the signal as the transmitter output power increases and to decrease the level of the signal as the transmitter output power decreases. In the preferred embodiment the method further includes adjusting the current consumption of a plurality of components of an RF transmitter chain in accordance with at least one of the level of the signal and the gain of the stage.
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Citations
28 Claims
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1. A method, comprising:
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determining a change in a radio frequency transmitter output power; varying, with a digital variable gain amplifier, a level of an input base band signal at an input of a digital to analog converter that outputs a signal to a radio frequency transmitter chain that comprises a phase modulator of the radio frequency transmitter, where the varying is according to the determined change in the radio frequency transmitter output power, comprising increasing the level of the signal as the radio frequency transmitter output power increases and decreasing the level of the signal as the radio frequency transmitter output power decreases; and adjusting a bias current of at least the phase modulator according to the varied level of the signal, comprising decreasing the bias current as the level of the signal is decreased and increasing the bias current as the level of the signal is increased. - View Dependent Claims (2, 3, 4, 5, 6, 25)
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7. A radio frequency transmitter, comprising:
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circuitry configured to determine a change in the radio frequency transmitter output power; the circuitry configured to vary, with a digital variable gain amplifier, a level of an input baseband signal at an input of a digital to analog converter that outputs a signal to a radio frequency transmitter chain that comprises a quadrature modulator of the radio frequency transmitter, where the varying is according to the determined change in the radio frequency transmitter output power, comprising the circuitry is configured to increase the level of the signal as the transmitter output power increases and to decrease the level of the signal as the transmitter output power decreases; and the circuitry further configured to adjust a bias current of at least the quadrature modulator according to the varied level of the signal, comprising the circuitry is configured to decrease the bias current as the level of the signal is decreased and increase the bias current as the level of the signal is increased. - View Dependent Claims (8, 9, 10, 11, 12, 13, 14, 15, 26)
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16. A mobile station comprising:
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a transmitter; circuitry configured to determine a change in the transmitter output power; circuitry configured to vary, with a digital variable gain amplifier, a level of an input baseband signal at an input of a digital to analog converter that outputs a signal to a radio frequency transmitter chain that comprises a quadrature modulator of the transmitter, where the level of the signal is varied according to the determined change in the transmitter output power, comprising the circuitry is configured to increase the level of the signal as the transmitter output power increases and to decrease the level of the signal as the transmitter output power decreases; and circuitry configured to adjust a bias current of at least the quadrature modulator according to the varied level of the signal, comprising the circuitry is configured to decrease the bias current as the level of the signal is decreased and increase the bias current as the level of the signal is increased. - View Dependent Claims (17, 18, 19, 27)
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20. An apparatus, comprising:
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a transmitter; a circuit configured to determine a change in the transmitter output power; the circuit configured to vary, with a digital variable gain amplifier, a level of an input base band signal at an input of a digital to analog converter that outputs a signal to a radio frequency transmitter chain that comprises a quadrature modulator of the transmitter, where the varying is according to the determined change in the transmitter output power, comprising the circuit is configured to increase the level of the signal as the transmitter output power increases and to decrease the level of the signal as the transmitter output power decreases; and the circuit further configured to adjust a bias current of at least the quadrature modulator according to the varied level of the signal, comprising the circuit is configured to decrease the bias current as the level of the signal is decreased and increase the bias current as the level of the signal is increased. - View Dependent Claims (21, 22, 23, 24, 28)
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Specification