EXHIBIT 5.1

September 25, 2000

Applied Micro Circuits Corporation
6290 Sequence Drive
San Diego, CA  92121

Re:  Registration Statement on Form S-8

Ladies and Gentlemen:

You have requested our opinion with respect to certain matters in connection
with the filing by Applied Micro Circuits Corporation (the "Company") of a
Registration Statement on Form S-8 (the "Registration Statement") with the
Securities and Exchange Commission, covering the registration of 34,575 shares
of the Company's Common Stock, $.01 par value (the "Shares"), issuable upon the
exercise of outstanding options issued pursuant to the SiLutia, Inc. 1999 Stock
Option Plan (the "Plan").  Such options were assumed by the Company in
connection with the Agreement and Plan of Merger and Reorganization dated as of
September 21, 2000 (the "Merger Agreement"), by and among the Company,
Satisfaction Acquisition Corp., SiLutia, Inc. and the stockholders of SiLutia,
Inc.

In connection with this opinion, we have examined and relied upon the
Registration Statement and related prospectus, the Plan, the form of option
agreement, the Merger Agreement, the Company's Certificate of Incorporation and
Bylaws, as amended, and the originals or copies certified to our satisfaction of
such records, documents, certificates, memoranda and other instruments as in our
judgment are necessary or appropriate to enable us to render the opinion
expressed below. We have assumed the genuineness and authenticity of all
documents submitted to us as originals, the conformity to originals of all
documents submitted to us as copies thereof and the due execution and delivery
of all documents where due execution and delivery are a prerequisite to the
effectiveness thereof.

On the basis of the foregoing, and in reliance thereon, we are of the opinion
that the Shares, when sold and issued in accordance with the Plan, the assumed
option agreements, the Registration Statement and related prospectus, will be
validly issued, fully paid, and nonassessable (except as to shares issued
pursuant to certain deferred payment arrangements, which will be fully paid and
nonassessable when such deferred payments are made in full).

We consent to the filing of this opinion as an exhibit to the Registration
Statement.

Very truly yours,

Cooley Godward LLP


/s/ D. Bradley Peck