Analog fourier transform channelizer and OFDM receiver
AssigneeVirginia Tech Intellectual Properties, Inc.
InventorsMark Lehne, Sanjay Raman
Life of this patent
Estimating the term…
Abstract
An OFDM receiver having an analog multiplier based I-Q channelizing filter, samples and holds consecutive analog I-Q samples of an I-Q baseband, the I-Q basebands having OFDM sub-channels. A lattice of analog I-Q multipliers and analog I-Q summers concurrently receives the held analog I-Q samples, performs analog I-Q multiplications and analog I-Q additions to concurrently generate a plurality of analog I-Q output signals, representing an N-point discrete Fourier transform of the held analog samples, the I-Q signals having relative phase and magnitude representing bits in the OFDM sub-channels. The phase and magnitude may represent QPSK. Optionally, a phase shift decoder receives the analog transform I-Q output signals and generates a corresponding binary bit data.
Claims12
An analog multiplier based I-Q channelizing filter, comprising:
- a bank of sample-and-hold (S/H) circuits, constructed and arranged to each receive an externally generated input signal, sample and hold N consecutive analog sample pairs, N>3, of the input signal, each sample pair being a sample of an in-phase baseband signal IS and a sample of a quadrature baseband signal QS, and concurrently output the N consecutive analog samples as N held analog sample pairs;
- a clock circuit generating a master clock ck and N phase-shifted divide-by-N clocks ck1, ck2, . . . , ckN, the clocks ck1, ck2, . . . , ckN being applied to and controlling a corresponding one of said bank of S/H circuits;
- and
- an analog-multiplier based Fourier Transform circuit, constructed and arranged to receive said N held analog samples and output a corresponding N analog transform signals representing an N-point discrete Fourier transform of said N held analog samples, wherein said Fourier Transform circuit includes a plurality of analog multipliers and analog summers.
An Orthogonal Frequency Division Multiplex (OFDM) receiver, comprising:
- an RF I-Q receiver constructed and arranged to receive an externally generated signal band, downconvert the received externally generated signal band to an in-phase baseband signal IS and a quadrature baseband signal QS;
- a first sample-and-hold (S/H) circuit including a pair of S/H circuits, one receiving the in-phase baseband signal IS and one receiving the quadrature baseband signal QS;
- an analog multiplier based I-Q channelizing filter, comprising:
- a bank of S/H circuits, constructed and arranged to sample and hold N consecutive analog sample pairs from said first S/H circuit, N>3, each sample pair being a sample of the in-phase baseband signal IS and a sample of the quadrature baseband signal QS, and concurrently output the N consecutive analog sample pairs as N held analog sample pairs,
- a clock circuit generating a master clock ck and N phase-shifted, divide-by-N clocks ck1, ck2, . . . , ckN, the master clock ck being applied to and controlling said first S/H circuit and the clocks ck1, ck2, . . . , ckN being applied to and controlling a corresponding one of said hank of S/H circuits;
- and
- an analog-multiplier based Fourier Transform circuit, having N inputs, N outputs, and a plurality of analog multipliers and analog summers connected between said N inputs and N outputs, constructed and arranged to receive said N held analog sample pairs on said N inputs, and output on said N outputs corresponding N analog transform signals, representing an N-point discrete Fourier transform of said N held analog samples, each of said N analog transform signals having an in-phase component signal and a quadrature component signal having respective magnitudes and polarities representing an I-Q phase and magnitude;
- and
- a bank of Binary Phase Shift Keying (BPSK) comparator/decoders connected to receive corresponding ones of said N analog transform signals and which output N bit streams as binary data, based on said I-Q phase and magnitude.
Dependencies are inferred from the claim text.