Ericsson Gmbh

Alan R Holden

Paul Wilkinson Dent

William O Camp, Jr

Antonio J Montalvo

Richard H Myers

Nikolaus Klemmer

Domenico Arpaia

David K Homol

A signal having a substantially uniform spectral distribution, e.g., a flat noise signal such as a signal ground, is provided at the input of a bandpass filter such as an IF filter of a receiver circuit, to thereby produce an output signal at the output of the bandpass filter. The output signal is processed in a limiter to produce a limited signal. An average frequency of the limited signal is determined, and the bandpass filter is adjusted based on the determined average frequency. According to one embodiment of the present invention, the bandpass filter comprises a Gm-C filter having a transconductance, and the filter is adjusted by adjusting the transconductance of the Gm-C filter based on the determined average frequency. According to another aspect of the present invention, a desired center frequency for the bandpass filter is identified. A resolution and a desired confidence interval are also identified. The number of samples of the limited signal needed to achieve the identified desired resolution and confidence interval is determined based on the identified desired center frequency. An average frequency is determined by sampling the limited signal to obtain a plurality of samples, the number of the plurality of samples being at least as great as the determined number of samples of the limited signal to achieve the identified desired resolution and confidence level, and determining the average frequency from the plurality of samples. The bandpass filter is adjusted based on the determined average frequency to achieve a center frequency for the bandpass filter that is within a predetermined range with respect to the desired center frequency. Related apparatus are also discussed.

Apparatus and methods for tuning bandpass filters

A stream of complex numbers is converted into polar form, including an amplitude-representative part and a phase-representative part. The amplitude-representative part of each of the converted complex numbers is represented as a plurality of digits of decreasing numerical significance. The phase-representative part of each of the converted complex numbers is phase-modulated at the radio carrier frequency to produce a phase-modulated drive signal. The phase-modulated drive signal is amplified in a plurality of power amplifiers. A respective one of the power amplifiers provides a maximum output power level at a respective amplifier output that is related to a respective one of the decreasing numerical significance. The output amplitude of a respective one of the plurality of power amplifiers is controlled by applying a respective one of the plurality of digits of decreasing numerical significance to a respective one of the plurality of power amplifiers. The amplifier outputs of the plurality of power amplifiers are combined to form the modulated radio power signal.

Systems and methods for converting a stream of complex numbers into an amplitude and phase-modulated radio power signal

A signal having a substantially uniform spectral distribution, e.g., a flat noise signal such as a signal ground, is provided at the input of a bandpass filter such as an IF filter of a receiver circuit, to thereby produce an output signal at the output of the bandpass filter. The output signal is processed in a limiter to produce a limited signal. An average frequency of the limited signal is determined, and the bandpass filter is adjusted based on the determined average frequency. According to one embodiment of the present invention, the bandpass filter comprises a Gm-C filter having a transconductance, and the filter is adjusted by adjusting the transconductance of the Gm-C filter based on the determined average frequency. According to another aspect of the present invention, a desired center frequency for the bandpass filter is identified. A resolution and a desired confidence interval are also identified. The number of samples of the limited signal needed to achieve the identified desired resolution and confidence interval is determined based on the identified desired center frequency. An average frequency is determined by sampling the limited signal to obtain a plurality of samples, the number of the plurality of samples being at least as great as the determined number of samples of the limited signal to achieve the identified desired resolution and confidence level, and determining the average frequency from the plurality of samples. The bandpass filter is adjusted based on the determined average frequency to achieve a center frequency for the bandpass filter that is within a predetermined range with respect to the desired center frequency . Related apparatus are also discussed.

Modulation systems and methods can modulate a stream of complex numbers representing a desired modulation of a radio signal by representing a real part of each of the complex numbers in a stream of complex numbers representing a desired modulation of a radio signal, as a plurality of first digits of decreasing numerical significance and representing an imaginary part of each of the complex numbers as a plurality of second digits of decreasing numerical significance. A respective one of the first digits and a respective one of the second digits of like numerical significance are grouped to form a plurality of phase control symbols. A respective phase control symbol is then used to control the phase of an output signal at the radio carrier frequency from a respective one of the plurality of power amplifiers. Each of the power amplifiers provides an output power level that is related to the numerical significance of the first and second digits that form the associated phase control symbol. The output power levels of the plurality of power amplifiers are combined to thereby form the modulated radio power signal.

Systems and methods for converting a stream of complex numbers into a modulated radio power signal

Power IQ modulation systems and methods include first and second power amplifiers, each including a signal input, a supply input and a power input. The first and second power amplifiers are preferably class-C power amplifiers. A source of first, second, third and fourth reference frequency signals is also provided. The first and second reference frequency signals are inverted relative to one another, and the third and fourth reference frequency signals are inverted relative to one another. Preferably, the first, second, third and fourth reference frequency signals are 0&deg;, 180&deg;, 90&deg; and 270&deg; phase shifted reference frequency signals, respectively. A switching system is also provided that selectively applies one of the first and second reference frequency signals to the signal input of the first power amplifier as a function of the polarity of one of the I and Q input signals. The switching system also selectively applies one of the third and fourth reference frequency signals to the signal input of the second power amplifier as a function of the polarity of the other of the I and Q input signals. A third amplifier, preferably a class-D amplifier, is responsive to the one of the I and Q input signals to supply a first variable supply voltage to the supply input of the first amplifier. A fourth amplifier, also preferably a class-D amplifier, is responsive to the other of I and Q input signals to supply a second variable supply voltage to the supply input of the second amplifier. A coupler couples the power outputs of the first and second power amplifiers to a load such as a radiotelephone antenna. Accordingly, power IQ modulation is provided that can use class-C and class-D amplifiers that are highly efficient.

Power IQ modulation systems and methods

A power-on reset circuit for resetting the register values contained on an integrated circuit upon power-up of the integrated circuit. The power-on reset circuit can be implemented either internal or external to the integrated circuit. The power-on reset circuit generates a reset signal as long as the supply voltage is not in the operational range and maintains the reset signal for a certain time after the supply voltage has returned to its nominal value. The power-on reset circuit also provides accurate detection of a serious supply voltage drop and has low power consumption. The power-on reset circuit comprises a battery, a voltage-referenced switching circuit, a current source, a capacitor and a voltage buffer.

Power-on reset circuit

An improved receiver architecture utilizing active filters for frequency conversion, wherein the final IF stage operates at a frequency higher than the previous IF stage, is disclosed to facilitate the processing by a baseband system operating at higher IF of signals from receivers operating at lower IFs and to enable the continued use of existing post-IF devices with multiple-conversion receivers. A low IF signal output is digitally mixed with a divided local oscillator signal to achieve a higher IF which is suited for processing by post-IF components such as a detector. The mixed signal is then filtered by a low dynamic range active filter and limited.

Growing community of inventors

Apex, NC, United States of America

Alan R Holden