Direct conversion wireless receiver with digital phase equalization
View Patent ↗A direct conversion receiver (DCR) with a pair of quadrature conversion paths. Each of the quadrature conversion paths receives an RF input signal and converts the RF input signal to a digital baseband signal. The quadrature conversion paths each include a mixer mixes the RF input signal with a carrier phase signal. Quadrature baseband signals from the mixer pass through an analog filter which provides a filtered baseband signal. An analog to digital converter (ADC) converts the quadrature baseband component to a digital baseband signal. A 5 th order elliptical filter filters the quadrature baseband component. The 5 th order elliptical filter may be before or after the ADC. A digital baseband component from the ADC and filtered by the 5 th order elliptical filter passes to a phase equalizer which compensates for phase distortion from the analog filter. The quadrature digital baseband outputs from the quadrature conversion paths are passed to a baseband processor.
1. A direct conversion receiver (DCR) comprising:
a pair of quadrature conversion paths, each of said quadrature conversion paths receiving an RF input signal and converting said RF input signal to a digital baseband signal, said each quadrature conversion path comprising:
a mixer mixing said RF input signal with a carrier phase signal,
an analog filter receiving a quadrature baseband signal from said multiplier and providing a filtered baseband signal,
an analog-to-digital converter (ADC) converting a quadrature baseband component to a digital baseband signal,
a 5 th order elliptical filter filtering said quadrature baseband component, and
a phase equalizer compensating for phase distortion arising in said analog filter; and
a baseband processor receiving quadrature digital baseband outputs from said pair of quadrature conversion paths and providing digital information therefrom.
2. A DCR as in claim 1 wherein each phase equalizer is a second order all pass digital phase equalizer.
3. A DCR as in claim 2 wherein the phase equalizer has a transfer function defined by
H
eq
(
z
)
=
b
0
+
b
1
z
-
1
+
b
2
z
-
2
a
0
+
a
1
z
-
1
+
a
2
z
-
2
where a0=b2, a1=b1, a2=b0.
4. A DCR as in claim 3 wherein each 5 th order elliptical filter receives the digital output of the ADC and provides said digital baseband component to the phase equalizer.
5. A direct conversion receiver (DCR) comprising:
a pair of quadrature conversion paths, each of said quadrature conversion paths receiving an RF input signal and converting said RF input signal to a digital baseband signal, said each quadrature conversion path comprising:
a mixer mixing said RF input signal with a carrier phase signal,
an analog filter receiving a quadrature baseband signal from said multiplier and providing a filtered baseband signal,
an analog-to-digital converter (ADC) converting a quadrature baseband component to a digital baseband signal,
a 5 th order elliptical digital filter receiving said quadrature baseband component and providing a filtered digital baseband component, and
a phase equalizer compensating said filtered digital baseband component for phase distortion arising in said analog filter, and
a baseband processor receiving quadrature digital baseband outputs from said pair of quadrature conversion paths and providing digital information therefrom.
6. A DCR as in claim 5 wherein each phase equalizer is a second order all pass digital phase equalizer.
7. A DCR as in claim 6 wherein the phase equalizer has a transfer function defined by
H
eq
(
z
)
=
b
0
+
b
1
z
-
1
+
b
2
z
-
2
a
0
+
a
1
z
-
1
+
a
2
z
-
2
where a0=b2, a1=b1, a2=b0.
8. A direct conversion receiver (DCR) comprising:
a pair of quadrature conversion paths, each of said quadrature conversion paths receiving an RF input signal and converting said RF input signal to a digital baseband signal, said each quadrature conversion path comprising:
a mixer mixing said RF input signal with a carrier phase signal,
an analog filter receiving a quadrature baseband signal from said multiplier and providing a filtered baseband signal,
a 5 th order elliptical filter filtering said filtered baseband signal and providing a quadrature baseband component,
an analog-to-digital converter (ADC) converting said quadrature baseband component to a digital baseband signal, and
a phase equalizer compensating said digital baseband signal for phase distortion arising in said analog filter; and
a baseband processor receiving quadrature digital baseband outputs from said pair of quadrature conversion paths and providing digital information therefrom.
9. A DCR as in claim 8 wherein each phase equalizer is a second order all pass digital phase equalizer.
10. A DCR as in claim 9 wherein the phase equalizer has a transfer function defined by
H
eq
(
z
)
=
b
0
+
b
1
z
-
1
+
b
2
z
-
2
a
0
+
a
1
z
-
1
+
a
2
z
-
2
where a0=b2, a1=b1, a2=b0.
11. A DCR as in claim 10 wherein the phase equalizer has a transfer function defined by
H
eq
(
z
)
=
b
0
+
b
1
z
-
1
+
b
2
z
-
2
a
0
+
a
1
z
-
1
+
a
2
z
-
2
where a0=b2, a1=b1, a2=b0.