Frequency translation and applications of same are described herein, including wireless local area network (WLAN) applications such as IEEE Standard 802.11 WLANs. Such applications include, but are not limited to, frequency down-conversion, frequency up-conversion, enhanced signal reception, unified down-conversion and filtering, and combinations and applications of same.

Wireless local area network (WLAN) technology and applications including techniques of universal frequency translation

Methods for down converting a modulated carrier signal to a demodulated baseband signal are described herein The method requires that a first portion of energy is transferred from the modulated carrier signal, and stored at a first storage device when a first switch is on At least some of the energy stored in the first storage device is discharged when the first switch is off The method further comprises transferring a second portion of energy from the modulated carrier signal, storing at a second storage device the second portion of transferred energy when a second switch is on, and discharging at least some of the energy stored in the second storage device when the second switch is off A down-converted in-phase baseband signal portion is generated from the energy accumulated in the first storage device while both the charging and the discharging occurs, and a down-converted inverted in-phase baseband signal portion is generated from the energy accumulated in the second storage device while both the charging and the discharging occurs, and the two portions are combined with a first differential amplifier circuit to form a down-converted differential in-phase baseband signal

Method and system for down-converting an electromagnetic signal

Methods, systems, and apparatuses, and combinations and sub-combinations thereof, for down-converting and up-converting an electromagnetic (EM) signal are described herein. Briefly stated, in embodiments the invention operates by receiving an EM signal and recursively operating on approximate half cycles (½, 1½, 2½, etc.) of the carrier signal. The recursive operations can be performed at a sub-harmonic rate of the carrier signal. The invention accumulates the results of the recursive operations and uses the accumulated results to form a down-converted signal. In an embodiment, the EM signal is down-converted to an intermediate frequency (IF) signal. In another embodiment, the EM signal is down-converted to a baseband information signal. In another embodiment, the EM signal is a frequency modulated (FM) signal, which is down-converted to a non-FM signal, such as a phase modulated (PM) signal or an amplitude modulated (AM) signal. Up-conversion is accomplished by controlling a switch with an oscillating signal, the frequency of the oscillating signal being selected as a sub-harmonic of the desired output frequency.

Method and system for down-converting and up-converting an electromagnetic signal, and transforms for same

The present invention includes a system and method for ensuring reception of a communications signal. A modulating baseband signal with desired information is accepted, and a plurality of redundant spectrums is generated. Each redundant spectrum comprises the necessary amplitude, phase, and frequency information to substantially reconstruct the modulating baseband signal. It is expected but not required that the redundant spectrums will be generated at a first location and sent to a second location over a communications medium. At the second location, the redundant spectrums are independently processed to recover a demodulating baseband signal for each of the redundant spectrums. In one embodiment, an error detection process is employed at the second location to detect and eliminate those demodulated baseband signals that have been corrupted during transmission. An error-free demodulated baseband signal is selected from the remaining demodulated baseband signals. The error-free demodulated baseband signal is representative of the modulating baseband signal sent over the communications medium.

Method and system for ensuring reception of a communications signal

Methods and apparatuses for reducing DC offsets in a communication system are described. In a first aspect, a feedback loop circuit reduces DC offset in a wireless local area network (WLAN) receiver channel. The frequency response of the feedback loop circuit can be variable. In a second aspect, a circuit provides gain control in a WLAN receiver channel. First and second automatic gain control (AGC) amplifiers are coupled in respective portions of the receiver channel. Circuits for monitoring DC offset, and for providing control signals for controlling the frequency response of the DC offset reducing circuits are also provided.

Method and apparatus for reducing DC offsets in a communication system

The invention relates to an electrical filter circuit operated with a definite sampling and clock frequency fT, such filter being made up of CTD elements, and having at least one bipolar or quadripolar resonator in the form of a self-contained conductor loop (for example, C1, C2) with unidirectional transmission behavior. Differences in the transfer capacitances of such circuits are reduced, as far as possible, in order to thereby simplify integrated manufacture as far as possible, by positioning the frequency band to be filtered out at a frequency position which lies above half the clock frequency (fT /2), or in the range from fT /2 through 3fT /2.

Electrical filter circuit operated with a definite sampling and clock frequency fT which consists of CTD elements

Aus ctd-elementen bestehende, mit einer vorgebbaren abtast- und taktfrequenz f tief t betriebene elektrische filterschaltung.

A resonator circuit formed in MOS technology for scanned analog signals, wherein such circuits are constructed for use with accumulators and information processing is accomplished by means of switched capacitors which are charged or respectively connected to each other by way of clock pulse transistors. In the present invention, the realization of general ladder networks or branching circuits for builders in single layer MOS techniques is accomplished by utilizing a second continuous branch which is switched to a first accumulator stage by clock pulse switches and is connected with a reference potential through a capacitor as well as to a further accumulator input through a series switch. The signal series arms are connected with the outputs of the total accumulator arrangement by way of time delay transit elements. The total accumulator arrangement is expanded to a resonator of the type of a four pole network having two inputs to which one respective transmission and one respective reflection output is assigned by utilizing difference elements and transfer elements. The arrangement of the invention is suitable for use as general branching filter circuits, and an increase of the dynamic range by better suppression of the clock pulse pickup and the harmonic distortion of the second order occurs by utilizing push-pull arrangements.

Resonator formed in integrated MOS technology utilizing switched capacitors

The system transmits speech channels and selector signals, using at least one electric filter circuit, consisting of charge transfer devices (CTD). The filter circuit contains dipole or four-pole resonators with closed conductor loops of unidirectional transmission characteristics. To the resonators are connected at least one CTD supply line and at least one CTD tapping line. The recharge capacity of the enclosed conductor loop is different from that of these two lines. The selector filter consists also of CTD elements and is controlled by a clock pulse frequency, derived from a carrier frequency, already available in the carrier frequency telephone system. Pref., the clock pulse signal is derived from a carrier frequency of 192 kHz. Several filters with a single clock pulse generating circuit can form an integrated circuit.

Carrier frequency telephone system with CTD elements - has CTD selection filter, controlled by clock pulse frequency derived from carrier frequency

The bandpass or bandstop filter circuit has a undirectional closed-loop resonator with charge transfer devices forming input and output lines to and from the loop. The capacitance of the loop is different from that of the input and output lines. The input and/or output lines each consist of at least two sublines (1-1', 2-2') each having a different number of CTD elements. A bridging line (c1) is separated by at least one CTD element e.g.(n2) from the closed loop (c3,c4). An inverting amplifier may be included in the bridging line or in the input or output line. The amplifier lies between the bridging line connection points and the closed loop. Either the bridging line and the bridged line have the same number of CTD elements or the bridged line has a number of CTD elements greater than the bridging line by the number of CTD elements in the closed loop.

Betzl Hermann Dipl Ing

Papers

Electrical filter circuit operated with a definite sampling and clock frequency fT which consists of CTD elements

Aus ctd-elementen bestehende, mit einer vorgebbaren abtast- und taktfrequenz f tief t betriebene elektrische filterschaltung.

Resonator formed in integrated MOS technology utilizing switched capacitors

Carrier frequency telephone system with CTD elements - has CTD selection filter, controlled by clock pulse frequency derived from carrier frequency

Closed-loop resonator filter circuit - has input and output lines of charge transfer devices connected to loop to sharpen response characteristics