GSM baseband receiver arrangement using digital signal processing
AssigneeNEC Corporation
InventorDavid Andrew Wheeler
Life of this patent
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Abstract
GSM baseband receiver arrangement using digital signal processing is disclosed. The baseband receiver arrangement comprises two channel for inphase (Iin) and quadrature (Qin) components of the received signal. The DC offset of each channel is separately estimated by accumulating samples from the outputs of the second filter stages M1 and M2 and dividing the result by 64. The result is then negated and applied to the digital DC offset controls I1 and I2. This two stage process ensures that the majority DC offset is removed prior to variable gain, and the residual DC offset is removed before digital frequency shifting. Applying DC offset correction before the digital frequency shifting ensures that DC is annulled for any subsequent shift.
Claims8
A baseband receiver arrangement for a GSM phone comprising in each of two channels for inphase and quadrature components of the received signals:
- a Sigma-Delta modulator for providing a high frequency single-bit data stream;
- a first digital filter for converting said data stream to a multi-bit signal at a multiple of the symbol rate;
- and
- a second digital filter for converting said multi-bit signal to a multi-bit output signal at the symbol rate.
A baseband receiver arrangement for a GSM phone comprising in each of two channels for inphase and quadrature components of the received signals:
- a Sigma-Delta mondulator for providing a high frequency single-bit data stream;
- a first digital filter for converting said data stream to a multi-bit signal at a multiple of the symbol rate;
- a second digital filter for converting said multi-bit signal to a multi-bit output signal at the symbol rate;
- and
- the baseband receiver arrangement further comprising a complex digital frequency shifter operating on the signals from the two channels and occurring between the first and second digital filter stages.
A baseband receiver arrangement for a GSM phone comprising in each of two channels for inphase and quadrature components of the received signals:
- a Sigma-Delta mondulator for providing a high frequency single-bit data stream;
- a first digital filter for converting said data stream to a multi-bit signal at a multiple of the symbol rate;
- a second digital filter for converting said multi-bit signal to a multi-bit output signal at the symbol rate;
- and
- the baseband receiver arrangement further comprising a split DC offset cancellation arrangement comprising a coarse analog DC offset cancellation section in each channel and a digital DC offset cancellation section in each channel operating on the output of the first digital filter stage.
A baseband receiver arrangement for a GSM phone comprising in each of two channels for inphase and quadrature components of the received signals:
- a Sigma-Delta mondulator for providing a high frequency single-bit data stream;
- a first digital filter for converting said data stream to a multi-bit signal at a multiple of the symbol rate;
- a second digital filter for converting said multi-bit signal to a multi-bit output signal at the symbol rate;
- and
- a digitally controlled analog gain control circuit in each channel, controlled by a common RMS signal level calculator deriving its inputs from the output of the first digital filter stages.
Dependencies are inferred from the claim text.