Radio receiver and/or transmitter including a programmable equalizer

• US 20060029171A1
• Filed: 08/05/2004
• Published: 02/09/2006
• Est. Priority Date: 08/05/2004
• Status: Active Grant

• Current Assignee: Avago Technologies General IP PTE Limited (Broadcom, Inc.)
• Original Assignee: Broadcom Corporation (Broadcom, Inc.)
• Inventors: Jensen, Henrik T.
• Granted Patent: US 7,394,881 B2
• Time in Patent Office: Days
• US Class Current: 375/350
• CPC Class Codes: H04L 2025/03394 FSK
• CPC Class Codes: H04L 2025/03401 PSK
• CPC Class Codes: H04L 25/03133 with a non-recursive structure H04L25/03127 takes precedence
• CPC Class Codes: H04L 25/03343 Arrangements at the transmitter end
• CPC Class Codes: H04L 27/18 Phase-modulated carrier systems, i.e. using phase-shift keying H04L27/32 takes precedence

Abstract

A radio receiver includes a low noise amplifier, a down conversion module, an analog to digital converter, and a digital demodulator. The low noise amplifier is operably coupled to amplify inbound radio frequency (RF) signals to produce amplified inbound RF signals. The down conversion module is operably coupled to convert the amplified inbound RF signals into low intermediate frequency (IF) signals. The analog to digital converter is operably coupled to convert the low IF signals into digital low IF signals. The digital demodulator is operably coupled to convert the digital low IF signals into inbound digital symbols and includes a baseband conversion module, a filtering module, a programmable equalizer, a CORDIC module, and a demodulation module. The baseband conversion module is operably coupled to convert the digital low IF signals into digital baseband signals. The filtering module is operably coupled to filter the digital baseband signals to produce filtered digital baseband signals. The programmable equalizer is operably coupled to equalize phase and frequency response of the filtered digital baseband signals such that the phase and frequency response of the filtered digital baseband signals approximates phase and frequency response of a square root raised cosine filter to produce adjusted digital baseband signals. The CORDIC module is operably coupled to produce phase and magnitude information from the adjusted digital baseband signals. The demodulation module is operably coupled to produce the inbound digital symbols from the phase and magnitude information.

Claims

1. A radio receiver comprises:

a low noise amplifier operably coupled to amplify inbound radio frequency (RF) signals to produce amplified inbound RF signals;

down conversion module operably coupled to convert the amplified inbound RF signals into low intermediate frequency (IF) signals;

analog to digital converter operably coupled to convert the low IF signals into digital low IF signals; and

a digital demodulator operably coupled to convert the digital low IF signals into inbound digital symbols, wherein the digital demodulator includes;

baseband conversion module operably coupled to convert the digital low IF signals into digital baseband signals;

filtering module operably coupled to filter the digital baseband signals to produce filtered digital baseband signals;

programmable equalizer operably coupled to equalize frequency response of the filtered digital baseband signals such that in-band frequency response of the radio receiver approximates frequency response of a square root raised cosine filter to produce adjusted digital baseband signals;

COordinate Rotation DIgital Computer (CORDIC) module operably coupled to produce phase and magnitude information from the adjusted digital baseband signals; and

demodulation module operably coupled to produce the inbound digital symbols from the phase and magnitude information.

2. The radio receiver of claim 1, wherein the programmable equalizer comprises:

a magnitude equalization stage operably coupled to equalize magnitude of the filtered digital baseband signals to produce magnitude equalized digital baseband signals; and

a group delay equalization stage operably coupled to equalize group delay of the magnitude equalized digital baseband signals to produce the adjusted digital baseband signals.

3. The radio receiver of claim 2, wherein the magnitude equalization stage comprises:

an infinite impulse response (IIR) filter having a transfer function approximating;

$H_{\mathrm{ME}}<br><br>\left(z\right)=\frac{b_0+b_1<br><br>z^{-1}+b_2<br><br>z^{-2}}{1+a_1<br><br>z^{-1}+a_2<br><br>z^{-2}},$

where b₀, b₁, b_{2 , a1} and a₂ are coefficients.

4. The radio receiver of claim 2, wherein the group delay equalization stage comprises:

an infinite impulse response (IIR) filter having a transfer function approximating;

$H_{\mathrm{GE}}<br><br>\left(z\right)=\frac{c_0+c_1<br><br>z^{-1}+z^{-2}}{1+c_1<br><br>z^{-1}+c_0<br><br>z^{-2}},$

where c₀ and c₁ are coefficients.

5. The radio receiver of claim 1, wherein the inbound digital symbols comprises at least one of:

multi-bit phase shift keying data; and

binary frequency shift keying data.

6. A radio transmitter comprises:

a digital modulator operably coupled to convert outbound digital symbols into outbound digital baseband signals, wherein the digital modulator includes;

pulse shaping module operably coupled to square root raised cosine filter the outbound digital symbols to produce filtered digital symbols;

COordinate Rotation DIgital Computer (CORDIC) module operably coupled to convert phase and magnitude information of the filtered digital symbols into outbound signals;

programmable equalizer operably coupled to produced equalized outbound signals by equalizing frequency response of the outbound signals such that in-band frequency response of the radio transmitter approximates frequency response of a square root raised cosine filter;

compensation module operably coupled to compensate at least one of an imbalance and DC offset of the equalized outbound signals to produce compensated outbound signals;

an interpolation filter operably coupled to increase sampling rate of the compensated outbound signals to produce up-sampled outbound signals; and

a re-quantization module operably coupled to quantize the up-sampled outbound signals to produce the outbound digital baseband signals;

digital to analog conversion module operably coupled to convert the outbound digital baseband signals into outbound analog baseband signals;

up-conversion module operably coupled to convert the outbound analog baseband signals into pre-amplified outbound RF signals; and

a power amplifier operably coupled to amplify the pre-amplified outbound RF signals to produce the outbound RF signals.

7. The radio transmitter of claim 6, wherein the programmable equalizer comprises:

a magnitude equalization stage operably coupled to equalize magnitude of the outbound signals to produce magnitude equalized outbound signals; and

a group delay equalization stage operably coupled to equalize group delay of the magnitude equalized outbound signals to produce the equalized outbound signals.

8. The radio transmitter of claim 7, wherein the magnitude equalization stage comprises:

an infinite impulse response (IIR) filter having a transfer function approximating;

$H_{\mathrm{ME}}<br><br>\left(z\right)=\frac{b_0+b_1<br><br>z^{-1}+b_2<br><br>z^{-2}}{1+a_1<br><br>z^{-1}+a_2<br><br>z^{-2}},$

where b₀, b₁, b₂ , a₁ and a₂ are coefficients.

9. The radio transmitter of claim 7, wherein the group delay equalization stage comprises:

an infinite impulse response (IIR) filter having a transfer function approximating;

$H_{\mathrm{GE}}<br><br>\left(z\right)=\frac{c_0+c_1<br><br>z^{-1}+z^{-2}}{1+c_1<br><br>z^{-1}+c_0<br><br>z^{-2}},$

where c₀ and c₁ are coefficients.

10. The radio transmitter of claim 6, wherein the outbound digital symbols comprises at least one of:

multi-bit phase shift keying data; and

binary frequency shift keying data.

11. A radio transceiver comprises:

a receiver section;

a transmitter section; and

a shared programmable equalizer,

wherein the receiver section includes;

a low noise amplifier operably coupled to amplify inbound radio frequency (RF) signals to produce amplified inbound RF signals;

down conversion module operably coupled to convert the amplified inbound RF signals into low intermediate frequency (IF) signals;

analog to digital converter operably coupled to convert the low IF signals into digital low IF signals; and

a digital demodulator operably coupled to convert the digital low IF signals into inbound digital symbols, wherein the digital demodulator includes;

baseband conversion module operably coupled to convert the digital low IF signals into digital baseband signals;

filtering module operably coupled to filter the digital baseband signals to produce filtered digital baseband signals;

the shared programmable equalizer operably coupled to equalize in-band frequency response of the receiver section such that the in-band frequency response of the receiver section approximates the frequency response of a square root raised cosine filter to produce adjusted digital baseband signals;

COordinate Rotation DIgital Computer (CORDIC) module operably coupled to produce phase and magnitude information from the adjusted digital baseband signals; and

demodulation module operably coupled to produce the inbound digital symbols from the phase and magnitude information;

wherein the transmitter section includes;

a digital modulator operably coupled to convert outbound digital symbols into outbound digital baseband signals, wherein the digital modulator includes;

pulse shaping module operably coupled to square root raised cosine filter the outbound digital symbols to produce filtered digital symbols;

COordinate Rotation DIgital Computer (CORDIC) module operably coupled to convert phase and magnitude information of the filtered digital symbols into outbound signals;

the shared programmable equalizer operably coupled to produce equalized outbound signals by equalizing in-band frequency response of the transmitter section such that the in-band frequency response of the transmitter section approximates the frequency response of a square root raised cosine filter;

compensation module operably coupled to compensate at least one of an imbalance and DC offset of the equalized outbound signals to produce compensated outbound signals;

an interpolation filter operably coupled to increase sampling rate of the compensated outbound signals to produce up-sampled outbound signals; and

a re-quantization module operably coupled to quantize the up-sampled outbound signals to produce the outbound digital baseband signals;

digital to analog conversion module operably coupled to convert the outbound digital baseband signals into outbound analog baseband signals;

up-conversion module operably coupled to convert the outbound analog baseband signals into pre-amplified outbound RF signals; and

a power amplifier operably coupled to amplify the pre-amplified outbound RF signals to produce the outbound RF signals.

12. The radio transceiver of claim 11, wherein the shared programmable equalizer comprises:

a magnitude equalization stage operably coupled to;

equalize magnitude of the filtered digital baseband signals to produce magnitude equalized digital baseband signals when the receiver section is active; and

equalize magnitude of the outbound signals to produce magnitude equalized outbound signals when the transmitter section is active; and

a group delay equalization stage operably coupled to;

equalize group delay of the magnitude equalized digital baseband signals to produce the adjusted digital baseband signals when the receiver section is active; and

equalize group delay of the magnitude equalized outbound signals to produce the equalized outbound signals when the transmitter section is active.

13. The radio transceiver of claim 12, wherein the magnitude equalization stage comprises:

an infinite impulse response (IIR) filter having a transfer function approximating;

$H_{\mathrm{ME}}<br><br>\left(z\right)=\frac{b_0+b_1<br><br>z^{-1}+b_2<br><br>z^{-2}}{1+a_1<br><br>z^{-1}+a_2<br><br>z^{-2}},$

where b₀, b₁, b₂, a₁ and a₂ are coefficients.

14. The radio transceiver of claim 12, wherein the group delay equalization stage comprises:

an infinite impulse response (IIR) filter having a transfer function approximating;

$H_{\mathrm{GE}}<br><br>\left(z\right)=\frac{c_0+c_1<br><br>z^{-1}+z^{-2}}{1+c_1<br><br>z^{-1}+c_0<br><br>z^{-2}},$

where c₀ and c₁ are coefficients.

15. The radio transceiver of claim 11, wherein the inbound digital symbols comprises at least one of:

multi-bit phase shift keying data; and

binary frequency shift keying data.

16. The radio transceiver of claim 11, wherein the outbound digital symbols comprises at least one of:

multi-bit phase shift keying data; and

binary frequency shift keying data.