Wireless transmitters
Transmitter circuits for generating baseband signals having low receiver-band noise are disclosed. In one embodiment, the transmitter circuit comprises an active filtering-and-amplifying component comprising a first input configured to receive a first input signal, and a first output configured to output a first output signal. The transmitter circuit further comprises a passive filtering component comprising a second input connected to the first output and configured to receive the first output signal, a passive pole arrangement comprising a number of switchable resistance elements and a capacitance element connected across the plurality of switchable resistance elements, and a second output configured to output a second output signal having reduced noise as compared to the first output signal. The transmitter still further comprises a number of feedback loops connecting the passive filtering component to the first input.
1. A transmitter circuit comprising:
an active filtering-and-amplifying component comprising:
a first input configured to receive a first input signal, and
a first output configured to output a first output signal;
a passive filtering component comprising:
a second input connected to the first output and configured to receive the first output signal,
a passive pole arrangement comprising a number of switchable resistance elements and a capacitance element connected across the switchable resistance elements, and
a second output configured to output a second output signal having reduced noise as compared to the first output signal; and
a number of feedback loops connecting the passive filtering component to the first input.
2. The transmitter circuit of claim 1 , wherein each switchable resistance element comprises a switch element and at least one resistance element.
3. The transmitter circuit of claim 1 , wherein the plurality of switchable resistance elements are connected in parallel.
4. The transmitter circuit of claim 1 , wherein each feedback loop comprises a feedback loop resistance element.
5. The transmitter circuit of claim 4 , wherein the feedback loop resistance element comprises a switch element and at least one resistance element.
6. The transmitter circuit of claim 1 , wherein the number of switchable resistance elements is equal to the number of feedback loops.
7. The transmitter circuit of claim 6 , wherein each feedback loop is connected to a single switchable resistance element.
8. The transmitter circuit of claim 1 , further comprising a control component configured to select a pair of resistive switching elements in the passive pole arrangement.
9. The transmitter circuit of claim 8 , wherein the control component is further configured to close the switches in the selected pair of resistive switching elements.
10. The transmitter circuit of claim 1 , further comprising:
a digital-to-analogue converter; and
a digitally-controlled oscillator, each of which is connected to the first input.
11. The transmitter circuit of claim 1 , wherein:
the first input signal comprises a baseband signal, and
the first output signal comprises a first filtered baseband signal.
12. The transmitter circuit of claim 11 , wherein:
the second output signal comprises a second filtered baseband signal.
13. The transmitter circuit of claim 12 , further comprising a mixer configured to up-convert the second filtered baseband signal to a radio frequency signal.
14. A transceiver comprising:
a number of transmitter circuits, each transmitter circuit comprising:
an active filtering-and-amplifying component comprising:
a first input configured to receive a first input signal, and
a first output configured to output a first output signal;
a passive filtering component comprising:
a second input connected to the first output and configured to receive the first output signal,
a passive pole arrangement comprising a number of switchable resistance elements and a capacitance element connected across the switchable resistance elements, and
a second output configured to output a second output signal having reduced noise as compared to the first output signal; and
a number of feedback loops connecting the passive filtering component to the first input.
15. The transceiver of claim 14 , further comprising a pre-power amplifier connected to each of the transmitter circuits.
16. The transceiver of claim 14 , wherein each transmitter circuit further comprises:
a digital-to-analogue converter; and
a digitally-controlled oscillator, each of which is connected to the first input.
17. The transceiver of claim 14 , wherein:
the first input signal comprises a baseband signal,
the first output signal comprises a first filtered baseband signal, and
the second output signal comprises a second filtered baseband signal.
18. The transceiver of claim 17 , wherein each transmitter circuit further comprises a mixer configured to up-convert the second filtered baseband signal to a radio frequency signal.
19. An integrated circuit comprising:
a transceiver comprising:
a number of transmitter circuits, each transmitter circuit comprising:
an active filtering-and-amplifying component comprising:
a first input configured to receive a first input signal, and
a first output configured to output a first output signal;
a passive filtering component comprising:
a second input connected to the first output and configured to receive the first output signal,
a passive pole arrangement comprising a number of switchable resistance elements and a capacitance element connected across the switchable resistance elements, and
a second output configured to output a second output signal having reduced noise as compared to the first output signal; and
a number of feedback loops connecting the passive filtering component to the first input.
20. The integrated circuit of claim 19 , wherein the transceiver is implemented in complementary metal-oxide-semiconductor technology.