EXHIBIT 23.1

CONSENT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM

We consent to the incorporation by
reference in the following Registration Statements:



| | (1) | Registration Statement (Form S-8 No. 333-40905) pertaining to the 1997 Employee Stock Purchase Plan;
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| | (2) | Registration Statement (Form S-8 No. 333-47185) pertaining to the 1982 Employee Incentive Stock Option Plan, the 1992 Stock Option Plan and the 1997 Directors Stock Option
Plan;
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| | (3) | Registration Statements (Form S-8 No. 333-76767, Form S-8 No. 333-71878 and Form S-8 No. 333-130589) pertaining to the 1998 Employee Stock Purchase Plan;
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| | (4) | Registration Statement (Form S-8 No. 333-74787) pertaining to the 1998 Stock Incentive Plan (formerly the 1998 Cimaron Communications Corporation Stock Incentive Plan);
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| | (5) | Registration Statements (Form S-3 No. 333-35404, Form S-3 No. 333-46586 and Form S-3 No. 333-76185) pertaining to the registration of shares of Applied Micro Circuits
Corporation Common Stock;
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| | (6) | Registration Statement (Form S-8 No. 333-41572) pertaining to the YuniNetworks, Inc. 1999 Equity Incentive Plan;
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| | (7) | Registration Statement (Form S-8 No. 333-46584) pertaining to the SiLUTIA, Inc. 1999 Stock Option Plan;
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| | (8) | Registration Statement (Form S-8 No. 333-48914) pertaining to the MMC Networks, Inc. 1993 Stock Plan, the MMC Networks, Inc. 1997 Stock Plan, the MMC Networks, Inc. 1997 Director
Option Plan and the MMC Networks, Inc. 1997 Employee Stock Purchase Plan;
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| | (9) | Registration Statement (Form S-8 No. 333-92507) pertaining to the 1992 Stock Option Plan;
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| | (10) | Registration Statements (Form S-8 No. 333-35408, Form S-8 No. 333-48912, Form S-8 No. 333-53282, and Form S-8 No. 333-99623) pertaining to the 2000 Equity Incentive Plan;
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| | (11) | Registration Statement (Form S-8 No. 333-57202) pertaining to the Raleigh Technology Corp. Equity Compensation Plan;
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| | (12) | Registration Statement (Form S-8 No. 333-110075) pertaining to the JNI Corporation 2000 Non-Qualified Stock Option Plan, the JNI Corporation Amended and Restated 1999 Stock Option
Plan, the Jaycor Networks, Inc. 1997 Stock Option Plan, as amended, and the 1992 Stock Option Plan, as amended; and
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| | (13) | Registration Statement (Form S-8 No. 333-114327) pertaining to the 3ware, Inc. 2002 Stock Plan, as amended, and the 3ware, Inc. Amended and Restated 1997 Stock Option Plan;
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of our report dated December 20, 2006, with respect to (1) the consolidated financial statements and schedule of Applied Micro Circuits
Corporation, and (2) managements assessment of the effectiveness of internal control over financial reporting and the effectiveness of internal control over financial reporting of Applied Micro Circuits Corporation included in the Annual
Report on Form 10-K for the year ended March 31, 2006, each filed with the Securities and Exchange Commission.

/s/    ERNST & YOUNG LLP

San Diego, California

January 2, 2007