Nxp B.v.

St-Ericsson Sa

Timothy John Ridgers

Yann Le Guillou

Petrus Gerardus Maria Baltus

Louis Praamsma

Fernand Courtois

Maja Vidojkovic

Renaud Comte

A bias circuit for a transistor amplifier, the bias circuit comprising a low-pass filter block, a reference transistor, a sum node, a reference current source, and a current difference block, wherein

Bias circuit for a transistor amplifier

A method for applying a modulation signal to a phase locked loop comprises filtering the modulation signal to provide a low frequency component and a high frequency for application to respectively the feedback and feedforward paths of a phase locked loop. The high frequency component is scaled by a gain factor before being applied to the feedforward path. The low frequency component is also scaled by a gain factor and applied to the feedforward path. The energy in a common low frequency range of the modulation signal and of the loop error signal is estimated, and the gain factors are modified dependent on the measured energy.

PLL calibration

A radio receiver comprises an input () for a modulated radio frequency signal, a frequency down converter () coupled to the input, the frequency down converter including quadrature mixers () for demodulating a received modulated radio frequency signal using a local oscillator signal. An analogue-to-digital converter () is coupled to receive demodulated signals from the mixing means. The analogue-to-digital converter, which may comprise a continuous time sigma delta converter, has an input for a sampling clock frequency (f s). A voltage controlled oscillator () provides the local oscillator signal and supplies a frequency divider () used to provide the sampling clock frequency. The dividing ratio (1/A) of the frequency divider is variable in response to variations in the strength of an 15 output signal from the digital-to-frequency converter and the variations in the frequency of the sampling clock frequency vary the gain of the analogue-to-frequency converter thereby providing automatic gain control.

Radio receivers

The system and method of the present invention provide a single mixer (-) with significantly reduced noise performance at a low cost by adding a current control circuit () that reduces the current in at least the switching stage () during polarity changes of the local oscillator (LO) signal (). Alternative embodiments (-) are provided for a single mixer having significantly reduced noise wherein the low-noise characteristic is enhanced by a further modification to the switching stage (-).

Low-noise mixer

A conversion device (CD) is dedicated to conversion of baseband analog I/Q input signals into RF signals in a transmitting path of a wireless communication equipment. This device (CD) comprises i) first (PP) and second (PP) processing paths each comprising i) an input node (IN, IN) receiving an input signal (I/Q), i) an input path (IP, IP) connected to the input node and delivering an input current representative of the input signal (I/Q), i) an amplification means (A, A) having first and second inputs fed with the input current and a common-mode current and outputting an amplified signal, and i) a transconductor (T, T) delivering first and second currents from the amplified signal, the first current feeding a negative feedback path connected to the first input of the amplification means and being essentially equal to the input current, and the second current being a chosen scaled copy of the first current and representative of a voltage difference between the input signals (I/Q), H) a common-mode input path (CIP) connected to the input nodes (IN, IN) and delivering the common-mode current from the input signals (I/Q) to feed the second input of each amplification means (A, A), and iii) a switch core (SC) for mixing the second current delivered by a chosen one of the transconductors (T, T) with a local oscillator RF carrier to deliver output RF signals representative of the input signals (I/Q).

Growing community of inventors

Bayeux, France

Timothy John Ridgers