| Patent Number |
Title Of Patent |
Date Issued |
| 7532873 |
DC offset cancellation in a zero IF receiver |
May 12, 2009 |
| This invention describes how to quickly cancel DC offsets that are present in the two quadrature paths of a zero intermediate frequency transceiver. Previously known techniques are not suitable for the 5 GHz WLAN standards because of the very short transmit to receive turn around times a |
| 7502603 |
DC cancellation in zero-IF receivers |
March 10, 2009 |
| Improved DC cancellation in zero-IF receivers for eliminating the DC offset that otherwise would be caused by the AC voltage on a coupling capacitor at the time of switching from AC coupling to DC coupling. The coupling capacitor normally is connected first as a high pass filter to b |
| 7319716 |
Transmitter image suppression in TDD transceivers |
January 15, 2008 |
| In a transceiver comprising a time-division-duplex (TDD) of transmit and receive functions, the characteristics of unwanted image signal energy being transmitted from the transceiver are determined, and thereafter feedback is provided to the transmitter to reduce this unwanted image |
| 7130595 |
Transmitter power amplifier ramping method |
October 31, 2006 |
| A method for reducing frequency glitches in a digital transceiver due to power amplifier input impedance variations. According to the method, the power amplifier is switched on after the end of a prior packet reception period and before a new packet transmission begins. Instead of rampin |
| 7110734 |
DC offset cancellation in a zero if receiver |
September 19, 2006 |
| This invention describes how to quickly cancel DC offsets that are present in the two quadrature paths of a zero intermediate frequency transceiver. Previously known techniques are not suitable for the 5 GHz WLAN standards because of the very short transmit to receive turn around times a |
| 7035341 |
Quadrature gain and phase imbalance correction in a receiver |
April 25, 2006 |
| The present invention utilizes circuitry, already present in receivers, to calibrate and correct for gain and phase errors in a transceiver device. The present invention employs a digital signal processor along with multiple phase shifters and all pass networks to ensure proper levels of |
| 6922555 |
Phase interpolation receiver for angle modulated RF signals |
July 26, 2005 |
| A phase interpolation receiver for receiving angle modulated radio frequency signals. The receiver comprises mixers for down-converting the received angle modulated signal to lower frequency signals, limiters, interpolation filters, and a demodulator. The mixers down-convert the rece |
| 6766148 |
Switched sideband frequency low-IF transmitter |
July 20, 2004 |
| A transmitter for transmitting a high frequency transmit signal generates a low intermediate frequency quadrature signal, and up-converts the low intermediate frequency quadrature signal to the high frequency transmit signal. The frequency spectrum of the high frequency transmit signal h |
| 6744829 |
Calibration of a quadrature receiver |
June 1, 2004 |
| A receiver is calibrated. First, it is ensured that an input of the receiver does not receive useful signals. Thereafter, quadrature output signals of the receiver are correlated and a relative phase of quadrature local oscillators signals, which are used to down-convert received sig |
| 6721548 |
High dynamic range low ripple RSSI for zero-IF or low-IF receivers |
April 13, 2004 |
| A received signal strength indicator operating at low intermediate of zero intermediate frequency is provided. The received signal strength indicator forms absolute values from an in-phase signal component and a quadrature signal component of a low or zero intermediate frequency signal t |
| 6717981 |
Transmitter image suppression in TDD transceivers |
April 6, 2004 |
| In a transceiver comprising a time-division-duplex (TDD) of transmit and receive functions, the characteristics of unwanted image signal energy being transmitted from the transceiver are determined, and thereafter feedback is provided to the transmitter to reduce this unwanted image |
| 6678312 |
Method for extending digital receiver sensitivity using analog correlation |
January 13, 2004 |
| Analog correlation techniques are used in a digital receiver portion of a spread spectrum transceiver to determine when to turn ON given digital receiver components. According to a particular embodiment, an analog correlator receives the down-converted in-phase and quadrature-phase o |
| 6625424 |
Autocalibration of a transceiver through nulling of a DC-voltage in a receiver and injecting of |
September 23, 2003 |
| A quadrature tranceiver has a transmitter, a receiver, and a common local oscillator. With the transmitter switched off and the receiver switched on, a DC-error in the receiver is nulled in servo loops in in-phase and a quadrature receiver paths. After settling, the servo loops provide o |
| 6621879 |
Digital radio system, a digital radio device, and a quadrature demodulator |
September 16, 2003 |
| A digital radio device having a quadrature demodulator that does not suffer from substantial amplitude roll-off at the relevant operating range. Such a device is obtained by a phase shifting network in a quadrature branch of the demodulator having a series arrangement of a resistor and a |
| 6442380 |
Automatic gain control in a zero intermediate frequency radio device |
August 27, 2002 |
| A zero intermediate frequency radio device has an antenna for receiving a radio frequency signal, and a frequency down converter for down converting the received radio frequency signal to a zero intermediate frequency signal. The radio device further has controllable amplifier stages, |
| 6366604 |
Compensation for phase errors caused by clock jitter in a CDMA communication system |
April 2, 2002 |
| A CDMA reverse link has a system for providing compensation for phase errors caused by clock jitter in a CDMA reverse link. After filtering, data spread by a pilot PN sequence is supplied to a shift register that produces several data samples for sequential cycles of an internal clock. |
| 6317067 |
Pulse density modulation based digital-to-analog conversion |
November 13, 2001 |
| An approach for converting an M-bit digital input value into an analog output signal involves separately processing the (M-N) number of most significant bits and the N number of least significant bits of the M-bit digital input value. The N number of least significant bits are converted |
| 6314279 |
Frequency offset image rejection |
November 6, 2001 |
| An approach for providing image rejection during signal down conversion involves phase shifting quadrature signals at a frequency other than the down converted center frequency. One or more phase shifters coupled to a summer/subtractor provide forty five (45) degrees and one hundred thir |
| 6169463 |
Quadrature modulator with set-and-forget carrier leakage compensation |
January 2, 2001 |
| A quadrature modulator with set-and-forget carrier leakage compensation. The quadrature modulator comprises an in-phase and a quadrature branch. In the in-phase and quadrature branches, real-time digital signals are converted to analog signals, the analog signals are filtered, and the |
| 6148047 |
DC offset compensation for zero if quadrature demodulator |
November 14, 2000 |
| The present invention provides dc offset compensation circuit (800) for a zero IF FM quadrature demodulator in an AMPS cellular mobile telephone system. A frequency offset is introduced to remove modulation inherent dc components from supervisory audio tones and Manchester codes from a |
| 6137353 |
Linearized integrated FM demodulator using a plurality of cascaded all-pass filters or a bessel |
October 24, 2000 |
| An approach for demodulating a frequency-modulated signal involves processing a frequency-modulated signal with a phase shifter network to provide a demodulated signal that has a relatively constant amplitude around the center frequency of the frequency-modulated signal and that exhi |
