US 7,072,626 B2 · Polar modulation transmitter

Abstract

A polar modulation transmitter circuit provides reduced ACPR in its output signal by controlling the relative delay between its envelope and phase modulation operations based on direct or indirect feedback measurement the output signal's ACPR. Such measurement and associated control may be based on a delay controller that includes an ACPR measurement circuit and a delay control circuit. Additionally, or alternatively, the polar modulation transmitter circuit provides a greatly extended transmit power control range by using a staged amplifier circuit that includes a driver amplifier circuit operating in combination with a power amplifier circuit to impart desired envelope modulation. In an exemplary embodiment, the driver amplifier circuit is implemented as differential transistor pairs responsive to tail current modulation. As such, the driver amplifier circuit is suited in particular for economical and space saving integration within a transmitter or transceiver integrated circuit (IC).

Claims29

Dependent claims

A method of generating a radio frequency output signal based on polar modulation, the method comprising:

generating a phase-modulated signal responsive to an input phase-modulation information signal;
generating the output signal by imparting envelope-modulation to the phase-modulated signal responsive to an input envelope-modulation information signal;
measuring an adjacent channel power ratio (ACPR) for the output signal by feeding back a portion of the output signal via a feedback circuit that generates a baseband measurement signal, detecting an envelope of the baseband measurement signal over a first bandwidth to obtain a first detection signal, and detecting an envelope of the baseband measurement signal over a second bandwidth to obtain a second detection signal, and obtaining an ACPR measurement signal by subtracting the second detection signal from the first detection signal;
and
controlling a relative delay between the phase-modulated and envelope-modulated information signals to reduce the measured ACPR.

2 more elements

A method of generating a radio frequency output signal based on polar modulation, the method comprising:

generating a phase-modulated signal responsive to an input phase-modulation information signal;
generating the output signal by imparting envelope modulation to the phase-modulated signal in tandem using a tail-current modulated driver amplifier circuit responsive to a first scaled envelope modulation signal and a supply-modulated power amplifier circuit responsive to a second scaled envelope modulation signal;
and
scaling an input amplitude modulation information signal by one or more scaling factors to generate the first and second scaled modulation signals as a function of the desired transmit power level.

1 more element

A radio frequency polar modulation transmitter to generate a RF output signal at a desired transmit power, the transmitter_comprising:

a transmitter circuit that generates a phase-and-envelope modulated output signal based on separate phase-modulation and envelope-modulation information signals input to the transmitter circuit;
and
a delay controller comprising a feedback circuit to obtain an analog feedback signal associated with the output signal of the transmitter, a measurement circuit, including first and second envelope detectors and an associated differencing amplifier, to generate an ACPR measurement signal based on the analog feedback signal, and a control circuit to generate a delay control signal responsive to the ACPR measurement signal, the delay controller configured to control a relative delay between the phase-modulation and envelope-modulation signals based on performing real-time ACPR measurement for the output signal.

Dependencies are inferred from the claim text.

Polar modulation transmitter

Life of this patent

Polar modulation transmitter

Life of this patent

Abstract

Claims29