Block downconverter using a SBAR bandpass filter in a superheterodyne receiver

• US 20020111151A1
• Filed: 02/15/2001
• Published: 08/15/2002
• Est. Priority Date: 02/15/2001
• Status: Abandoned Application

• Current Assignee: National Instruments Corporation (Emerson Electric Company)
• Original Assignee: National Instruments Corporation (Emerson Electric Company)
• Inventors: Yee, Hon, Vasudev, Sheela N., Vasudev, Prahalad K., Irion, Reed A.
• Application Number:
  US09/785,081
• Publication Number:
  US 20020111151A1
• Time in Patent Office: Days
• US Class Current: 455/325
• CPC Class Codes: H04H 40/90 specially adapted for satellite broadcast receiving

Abstract

Several embodiments of a block downconverter using a SBAR bandpass filter in a superheterodyne receiver are disclosed. The block downconverter is coupled to receive a radio frequency input that includes a target region. The block downconverter is configured to produce a selected one of an overlapping plurality of portions of the target region as an intermediate frequency (IF) block having a fixed center frequency. Furthermore, the block downconverter includes a semiconductor bulk acoustic resonator (SBAR) filter that operates as an IF filter.

Claims

1. An apparatus, comprising:

a block downconverter coupled to receive a radio frequency input including a target region and configured to produce a selected one of an overlapping plurality of portions of the target region as an intermediate frequency (IF) block having a fixed center frequency;

wherein the block downconverter includes a semiconductor bulk acoustic resonator (SBAR) filter, wherein the SBAR filter operates as an IF filter in the block downconverter.

2. The apparatus of claim 1, wherein the SBAR filter comprises a piezoelectric resonator.

3. The apparatus of claim 1, wherein the SBAR filter comprises:

a layer of piezoelectric material;

a pair of electrodes mounted on one surface of the piezoelectric material; and

a third electrode mounted on an opposing surface of the piezoelectric material;

each electrode of the pair mounted in overlapping relation to the third electrode to create two series connected resonators that are the only connections to the third electrode.

4. The apparatus of claim 3, wherein the two series connected resonators have identical resonant frequency.

5. The apparatus as recited in claim 1, wherein the SBAR filter comprises a piezoelectric resonator-based T network.

6. The apparatus as recited in claim 1, wherein the SBAR filter comprises a piezoelectric resonator-based pi network.

7. The apparatus as recited in claim 1, wherein the SBAR filter comprises a piezoelectric resonator-based L network.

8. The apparatus as recited in claim 1, wherein the apparatus is a communications signal analyzer.

9. The apparatus as recited in claim 1, wherein the block downconverter comprises a first IF section configured to produce a first IF signal having a center frequency of 3.2 GHz, wherein the first IF section further comprises the SBAR filter, and wherein the SBAR filter has a center frequency of 3.2 GHz and is configured to filter the first IF signal.

10. A block downconverter, comprising:

a radio frequency section coupled to receive a radio frequency input and configured to produce a target region of the radio frequency input;

a local oscillator configured to produce a local oscillator signal having a frequency greater than a highest frequency of the target region of the radio frequency input;

an intermediate frequency (IF) section coupled to receive the target region and the local oscillator signal, wherein the IF section is configured to heterodyne electromagnetic waves in the target region within the local oscillator signal to produce an IF frequency band, and wherein a lowest frequency of the IF frequency band is greater than the highest frequency of the target region of the radio frequency input.

wherein the IF section comprises one or more semiconductor bulk acoustic resonator (SBAR) bandpass filter comprising at least one SBAR, and wherein one of the SBAR bandpass filters has a center frequency which is the same as a center frequency of the IF frequency band;

wherein the target region of the radio frequency input extends from about 9 kHz to approximately 2.6 GHz;

wherein the local oscillator signal varies from about 3.2 GHz to approximately 5.8 GHz;

wherein the local oscillator signal is variable in increments of about 1 MHz; and

wherein the IF frequency band has a center frequency of about 3.2 GHz.

11. A method of block downconverting an RF signal having a frequency from about 9 kHz to approximately 2.6 GHz, comprising:

receiving the RF signal;

mixing a 20 MHz band of the received RF signal with a signal from a local oscillator to produce a first IF band having a center frequency of 3.2 GHz;

passing the first IF band through an SBAR bandpass filter having a center frequency of 3.2 GHz; and

producing a target region of the received RF signal.

12. The method as recited in claim 11, wherein the SBAR filter comprises a piezoelectric resonator-based T network.

13. The method as recited in claim 11, wherein the SBAR filter comprises a piezoelectric resonator-based pi network.

14. The method as recited in claim 11, wherein the SBAR filter comprises a piezoelectric resonator-based L network.