Tunable RF N-path filter

Patent metadata

Field	Value
Publication number	US-9407482-B2
Application number	US-201314077072-A
Country	US
Kind code	B2
Filing date	Nov 11, 2013
Priority date	Nov 11, 2013
Publication date	Aug 2, 2016
Grant date	Aug 2, 2016

Abstract

Methods and apparatus, including computer program products, are provided for tunable filters. In one aspect there is provided an apparatus. The apparatus may include a bandpass filter comprising a resistive-capacitive configuration of N-path filters tunable to a first center frequency based on at least a first clock frequency; a notch filter comprising a capacitive-resistive configuration of N-path filters tunable to a second center frequency based on at least a second clock frequency; and a combiner coupled to the bandpass filter and the notch filter to combine a bandpass output signal provided by the bandpass filter and a notch output signal provided by the notch filter, wherein the combiner outputs a combined output. Related apparatus, systems, methods, and articles are also described.

First claim

What is claimed:

1. An apparatus comprising:
a bandpass filter comprising a resistive-capacitive configuration of N-path filters tunable to a first center frequency based on at least a first clock frequency;
a notch filter comprising a capacitive-resistive configuration of N-path filters tunable to a second center frequency based on at least a second clock frequency;
a combiner coupled to the bandpass filter and the notch filter to combine a bandpass output signal provided by the bandpass filter and a notch output signal provided by the notch filter, wherein the combiner outputs a combined output; and
a splitter coupled to the bandpass filter and the notch filter, wherein the splitter provides a differential signal to an input of the notch filter and the bandpass filter.

2. The apparatus of claim 1 , wherein the splitter comprises a balun.

3. The apparatus of claim 1 , wherein the combiner comprises a differential difference amplifier.

4. The apparatus of claim 1 further comprising:
a clock to tune at least one of the first center frequency and the second center frequency by at least varying a frequency of at least one of the first clock and the second clock.

5. The apparatus of claim 1 , wherein the first clock frequency and the second clock frequency are the same frequency.

6. The apparatus of claim 1 , wherein the resistive-capacitive configuration of N-path filters comprises one or more transistors coupled to one or more capacitors.

7. The apparatus of claim 1 , wherein the first center frequency comprises a center of a pass band of the bandpass filter.

8. The apparatus of claim 1 , wherein the second center frequency comprises a center of a notch band of the notch filter.

9. The apparatus of claim 1 , wherein the combined output includes a notch frequency at a frequency offset from the second clock frequency.

10. A method comprising:
receiving, at a bandpass filter, a differential signal, wherein the bandpass filter comprises a resistive-capacitive configuration of N-path filters tunable to a first center frequency based on at least a first clock frequency;
receiving, at a notch filter, the differential signal, wherein the notch filter comprises a capacitive-resistive configuration of N-path filters tunable to a second center frequency based on at least a second clock frequency;
combining, by a combiner coupled to the bandpass filter and the notch filter, a bandpass output signal provided by the bandpass filter and a notch output signal provided by the notch filter, wherein the combiner outputs a combined output; and
splitting, by a balun, a radio frequency signal to generate the differential signal.

11. The method of claim 10 , wherein the combiner comprises a differential difference amplifer.

12. The method of claim 10 , wherein the first clock frequency and the second clock frequency are the same frequency.

13. The method of claim 10 further comprising:
varying a first clock frequency and a second clock frequency to vary at least one of the first center frequency and the second center frequency.

14. An apparatus comprising:
means for receiving, at a bandpass filter, a differential signal, wherein the bandpass filter comprises a resistive-capacitive configuration of N-path filters tunable to a first center frequency based on at least a first clock frequency;
means for receiving, at a notch filter, the differential signal, wherein the notch filter comprises a capacitive-resistive configuration of N-path filters tunable to a second center frequency based on at least a second clock frequency;
means for combining, by a combiner coupled to the bandpass filter and the notch filter, a bandpass output signal provided by the bandpass filter and a notch output signal provided by the notch filter, wherein the combiner outputs a combined output; and
means for splitting a radio frequency signal to generate the differential signal.

15. A non-transitory computer-readable storage medium including computer program code, which when executed by at least one processor circuitry causes operations comprising:
receiving a radio frequency signal;
filtering, by an N-path bandpass filter tunable to a first center frequency having a pass band, a received radio frequency signal into a first output signal;
suppressing, by an N-path notch filter tunable to a second center frequency, the received radio frequency signal into a second output signal;
combining, by a combiner coupled to the N-path bandpass filter and the N-path notch filter, the first output signal provided by the N-path bandpass filter and the second output signal provided by the N-path notch filter; and
splitting, by a balun, a radio frequency signal to generate the differential signal.

Assignees

• Nokia Corp
• Nokia Technologies Oy

Inventors

• Aggarwal Sudhir
• Hasan Md Naimul

Classifications

• H04J3/025

  Filter arrangements (H04J3/08 takes precedence; filters per se H03H7/00, H03H9/00) · CPC title

• H03H19/002 Primary

  N-path filters · CPC title

• H04L27/148 Primary

  using filters, including PLL-type filters · CPC title