Envelope Tracking Signal Bandwidth Control
AssigneeBroadcom Corporation
InventorsSriraman Dakshinamurthy, Robert Gustav Lorenz
Life of this patent
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Abstract
An envelope tracking circuit for a transmit and receive path for a telecommunications device includes a filter to reduce the bandwidth of the transmit signal. The envelope of the filtered signal having the lower bandwidth is used to dynamically modulates the power amplifier voltage supply signal. The filter depends on current instantaneous values and also depends in a nonlinear way on instantaneous past and future values of the envelope tracking signal. The filter may be symmetric about peaks of the transmitted signal.
Claims24
A system comprising:
- an envelope circuit configured to receive a transmit signal and produce an envelope signal representative of an envelope of the transmit signal;
- a power amplifier configured to amplify the transmit signal;
- a filter configured to receive the envelope signal and produce a filtered envelope signal, the filter implementing a nonlinear filter function that depends on a current instantaneous value of the envelope signal and depends nonlinearly on past instantaneous values of the envelope signal and future instantaneous values of the envelope signal;
- an envelope tracking circuit coupled to the filter and responsive to the filter envelope signal and coupled to the power amplifier to provide a power supply signal to power the power amplifier, the envelope tracking circuit producing the power supply signal according to the envelope of the filter output signal.
A method comprising:
- at a communication device, receiving a transmit signal for radio transmission;
- producing an envelope signal of the envelope of the transmit signal;
- amplifying the transmit signal in a power amplifier;
- filtering the envelope signal to reduce bandwidth of the envelope signal and produce a filtered envelope signal;
- and
- applying to the power amplifier a voltage supply signal having a voltage magnitude that tracks the envelope of the filtered envelope signal.
A communication device comprising:
- an antenna;
- system logic to control operation of the communication device;
- a transmit and receive path comprising:
- a baseband controller to produce a transmit signal;
- a power amplifier coupled to the baseband controller and the antenna to amplify the transmit signal and apply the amplified signal to the antenna for transmission from the communication device;
- an envelope tracking circuit coupled to the envelope circuit, the power amplifier and the baseband controller, the envelope tracking circuit comprising:
- an envelope circuit configured to produce an envelope signal representative of an envelope of the transmit signal;
- an envelope tracking power supply coupled to the envelope circuit and the power amplifier to provide a dynamically variable power supply signal to the power amplifier by tracking the envelope signal;
- and
- a filter coupled to the baseband controller to produce a filtered signal as the envelope signal by applying a non-linear filter function to the envelope signal using instantaneous current values, instantaneous past values and instantaneous future values with a non-linear dependency on the instantaneous past values and instantaneous future values.
A method for reducing bandwidth of an envelope tracking power supply in a telecommunication device, the method comprising:
- receiving a transmit signal;
- generating an envelope signal of the transmit signal;
- filtering the envelope signal in a filter which depends non-linearly on future values of the envelope signal.
A method for reducing bandwidth of an envelope tracking power supply in a telecommunication device, the method comprising:
- receiving a transmit signal;
- storing current and future values of the transmit signal;
- generating an envelope signal of the transmit signal;
- filtering the envelope signal in a filter so that the instantaneous value of the envelope amplitude is a function of both amplitude of the current transmit signal value as well as the amplitude of a stored future value of the transmit signal.
Dependencies are inferred from the claim text.