Tunable filters, cancellers, and duplexers based on passive mixers

• US 9,800,278 B2
• Filed: 09/06/2016
• Issued: 10/24/2017
• Est. Priority Date: 09/04/2015
• Status: Active Grant

• Current Assignee: Archaius LLC
• Original Assignee: Physical Devices, LLC, North Carolina State University (University of North Carolina System)
• Inventors: Floyd, Brian Allan, Wilson, III, Charley Theodore, Bonner-Stewart, Jeffrey Franklin, Vosburgh, Frederick
• Primary Examiner(s): Trinh, Sonny
• Application Number:
  US15/257,354
• Publication Number:
  US 20170070251A1
• Time in Patent Office: 413 Days
• Field of Search: 455296, 455 78
• CPC Class Codes: H03D 2200/0074 using a resistive mixer or a passive mixer
• CPC Class Codes: H03D 7/165 at least two frequency changers being located in different paths, e.g. in two paths with carriers in quadrature combined with amplitude demodulation H03D1/2245, combined with angle demodulation H03D3/007; N-path filters H03H19/002
• CPC Class Codes: H03H 7/20 Two-port phase shifters providing an adjustable phase shift
• CPC Class Codes: H03H 7/463 Duplexers
• CPC Class Codes: H04B 1/1036 with automatic suppression of narrow band noise or interference, e.g. by using tuneable notch filters H04B1/123 takes precedence; filter circuits H03H
• CPC Class Codes: H04B 1/1081 Reduction of multipath noise by equalising H04B7/005
• CPC Class Codes: H04B 1/18 Input circuits, e.g. for coupling to an antenna or a transmission line coupling networks between antennas or lines and receivers independent of the nature of the receiver H03H
• CPC Class Codes: H04L 7/0016 correction of synchronization errors

Abstract

Tunable filters, cancellers, and duplexers based on passive mixers. A tunable delay cell includes passive mixers electrically coupled together for receiving an input signal and outputting a delayed signal, each passive mixer comprising a plurality of mixer switches. The tunable delay includes a control circuit for providing, to each passive mixer, a respective plurality of local oscillator (LO) signals, one to each mixer switch of each passive mixer. The control circuit is configured to vary the LO signals to cause a target frequency band of the input signal to be delayed by a target delay time in propagating through the passive mixers.

Claims

1. A tunable duplexer comprising:

one or more antennas;

an isolator electrically coupled to the one or more antennas for isolating a received signal and a transmitted signal on the one or more antennas;

a combiner comprising a first input electrically coupled to the one or more antennas; and

a feedforward path, between a coupler of the transmitted signal and a second input of the combiner, configured to cancel leakage across the isolator, wherein the feedforward path comprises a tunable delay cell comprising a plurality of passive mixers electrically coupled together for receiving an input signal and outputting a delayed signal, each passive mixer comprising a plurality of mixer switches.

2. The tunable duplexer of claim 1, wherein the tunable delay cell comprises a control circuit for providing, to each passive mixer, a respective plurality of local oscillator (LO) signals, one to each mixer switch of each passive mixer, and wherein the control circuit is configured to vary the LO signals to cause a target frequency band of the input signal to be delayed by a target delay time in propagating through the passive mixers.

3. The tunable duplexer of claim 1, wherein the feedforward path comprises a tunable attenuator.

4. The tunable duplexer of claim 1, comprising a reflective-type tunable filter electrically coupled to an output of the combiner.

5. The tunable duplexer of claim 4, comprising a second feedforward path, between the output of the combiner and one or more reflective loads of the reflective-type tunable filter, configured to cancel leakage over a directional coupler of the reflective-type tunable filter, wherein the second feedforward path is configured to cancel the leakage over the directional coupler by virtue of a down-converting mixer configured to downconvert a feedforward signal on the second feedforward path to baseband before the feedforward signal is coupled to one or more reflective loads of the reflective-type tunable filter.

6. The tunable duplexer of claim 5, comprising a third feedforward path, between the feedforward path and the one or more reflective loads of the reflective-type tunable filter, configured to further cancel leakage over the isolator.

7. A tunable duplexer comprising:

one or more antennas;

an isolator electrically coupled to the one or more antennas for isolating a received signal and a transmitted signal on the one or more antennas;

a combiner comprising a first input electrically coupled to the one or more antennas;

a reflective-type tunable filter electrically coupled to an output of the combiner; and

a feedforward path, between the output of the combiner and one or more reflective loads of the reflective-type tunable filter, configured to cancel leakage across a directional coupler of the reflective-type tunable filter, wherein the feedforward path is configured to cancel the leakage by virtue of one or more passive mixers in the feedforward path.

8. A tunable duplexer comprising:

one or more antennas;

an isolator electrically coupled to the one or more antennas for isolating a received signal and a transmitted signal on the one or more antennas;

a reflective-type tunable filter electrically coupled to the one or more antennas; and

a feedforward path, between a coupler of the transmitted signal and one or more reflective loads of the reflective-type tunable filter, configured to cancel leakage across the isolator.