Philips Electronics North America Corporation

Farbod Behbahani

Ali Fotowat-Ahmady

Nasrollah S Navid

Nasrollah Saeed Navid

Dan Linebarger

An RF mixer utilizing frequency and bias compensation for improved performance characteristics. The RF mixer receives bias signals that are dependent on V.sub.CC levels to internally balance the local oscillation received and mix the perfectly bias balanced internally generated oscillation signal with the RF input.

Low voltage temperature and V.sub.cc compensated RF mixer

A method and a circuit for self-calibration and testing QPSK transmitter/receiver IC's is provided. The method and circuit enable variable error parameters such as gain mismatch, offset voltages, and phase errors inherent in the circuit and signals to be measured and taken into account by the digital signal processors for minimum bit error rates during cellular communications.

Method and apparatus for self-calibration and testing of ZPSK

Self-oscillation of a prescalar circuit is avoided by including offset generators on the inputs of the prescalar circuit. This ensures that when the transistors in one differential pair in the prescalar circuit transition from ON to OFF, the other differential pair of transistors will not transition. As a result, spikes are prevented in the differential pair that does not have a transition. A quadrature signal generator constructed with such a prescalar circuit provides an accurate output despite weak or non-existent input signals.

Quadrature signal generator with spike-less prescalar circuit

A comparator has a simple high frequency signal path from input to output formed by two differentially connected transistors with an output transistor connected to each. A current control circuit maintains a constant total current flowing through the differentially connected transistors. The ratio of currents flowing through the differentially connected transistors is initially set by a control circuit, so that the output of the comparator is predictable when powered up. The control circuit then gradually releases control, so that there is a smooth transfer to control by a reference signal input to the comparator.

Growing community of inventors

Inglewood, CA, United States of America

Farbod Behbahani