<PAGE>

                                                                   EXHIBIT 10.16

                              SUBLEASE

1.   Parties. This Sublease is entered into by and between HRG, Inc., The Human
                                                           --------------------
     Resource Group, Sublessor, and Synplicity, Inc., Sublessee, as a Sublease
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     under the Master Lease dated May 19, 1993, entered into by WBC Rancho
                                  ------------                  ----------
     Bernardo Partners as Lessor, and Sublessor under this Sublease as Lessee; a
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     copy of the Master Lease is attached hereto as Exhibit A.

2.   Provisions Constituting Sublease.
     (a) This Sublease is subject to all of the terms and conditions of the
     Master Lease in Exhibit A and Sublessee shall assume and perform the
     obligations of Sublessor and Lessee in said Master Lease, to the extent
     said terms and conditions are applicable to the Premises subleased pursuant
     to this sublease. Sublessee shall not commit or permit to be committed on
     the Premises any act or omission which shall violate any term or conditions
     of the Master Lease. In the event of the termination of Sublessor's
     interest as Lessee under the Master Lease for any reason, then this
     Sublease shall terminate coincidentally therewith without any liability of
     Sublessor or Sublessee.

     (b) All of the terms and conditions contained in the Exhibit A Master Lease
     are incorporated herein, except for Sections 1.5, 1.6, 1.7, 49, 49b, 49c,
                                                  ----------------------------
     49d,50, 51, 52, 53 as terms and conditions of this Sublease (with each
     ------------------
     reference therein to Lessor and Lessee to be deemed to refer to Sublessor
     and Sublessee) and, along with all of the following Sections set out in
     this Sublease, shall be the complete terms and conditions of this Sublease.

3.   Premises. Sublessor leases to Sublessee and Sublessee hires from Sublessor
     the following described Premises together with the appurtenances, situated
     in the City of San Diego, County of San Diego, State of California located
                    ---------            ---------           ----------
     at 17055 Via del Campo, 1st Floor, space consisting of one (1) office known
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     as Office 109.
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4.   Rental. Sublessee shall pay to Sublessor as rent for the Premises in
     advance on the first day of each calendar month of the term of this
     Sublease without deduction, offset, prior notice or demand, in lawful money
     of the United States, the sum of Five Hundred & no/100 ($500.00). If the
                                      --------------------------------
     commencement date is not the first day of the month, or if the Sublease
     termination date is not the last day of the month, a prorated installment
     shall be paid at the then current rate for the fractional month during
     which the Sublease commences and/or terminates.

     Receipt of $0 is hereby acknowledged for rental for the first month, and
                --
     the additional amount or $0 as non-interest bearing security for
                              --
     performance under this Sublease. At Lessor's determination, this security
     deposit shall be used for repair and renovation as needed and/or credit
     against final month's rent. In the event Sublessee has performed all of the
     terms and conditions of this Sublease throughout the term, upon Sublessee
     vacating the Premises, the amount paid as a security deposit shall be
     returned to Sublessee after first deducting any sums owing to Sublessor.
<PAGE>

5.   Term.
     (a) The term of this Sublease shall be for a period of Twenty Two (22)
                                                            ---------------
     Months commencing on December 1, 1999, and ending on September 30, 2001.
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     At that time you may negotiate to renew the sublease at terms mutually
     agreeable. Note that a 30-day written notice is required should the
     Sublessee choose to renew or not to renew this sublease.

     (b) In the event Sublessor is unable to deliver possession of the Premises
     at the commencement of the term, Sublessor shall not be liable for any
     damage caused thereby, nor shall this Sublease be void or voidable but
     Sublessee shall not be liable for rent until such time as Sublessor offers
     to deliver possession of the Premises to Sublessee, but the term hereof
     shall not be extended by such delay. If Sublessee, with Sublessor's
     consent, takes possession prior to the commencement of the term, Sublessee
     shall do so subject to all of the covenants and conditions hereof and shall
     pay rent for the period ending with the commencement of the term at the
     same rental as that prescribed for the fast month of the term, prorated at
     the rate of 1/30th thereof per day.

6.   Use. Sublessee shall use the Premises for General Office and for no other
                                               --------------
     purpose without the prior written consent of Sublessor.

     Sublessee's business shall be established and conducted throughout the term
     hereof in a fast class manner. Sublessee shall not use the Premises for, or
     carry on, or permit to be carried on, any offensive, noisy or dangerous
     trade, business, manufacture or occupation nor permit any auction sale to
     be held or conducted on or about the Premises. Sublessee shall not do or
     suffer anything to be done upon the Premises which will cause structural
     injury to the Premises or the building of which the Premises form a part.
     The Premises shall not be overloaded and no machinery, apparatus or other
     appliance shall be used or operated in or upon the Premises which will in
     any manner injure, vibrate or shake the Premises or the building of which
     it is a part. No use shall be made of the premises which will in any way
     impair the efficient operation of the sprinkler system (if any) within the
     building containing the Premises. Sublessee shall not leave the Premises
     unoccupied or vacant during the term. No musical instrument of any sort, or
     any noise making device will be operated or allowed upon the Premises for
     the purpose of attracting trade or otherwise. Sublessee shall not use or
     permit the use of the Premises or any part thereof for any purpose which
     will increase the existing rate of insurance upon the building in which the
     Premises are located, or cause a cancellation of any insurance policy
     covering the building or any part thereof. If any act on the part of
     Sublessee or use of the Premises by Sublessee shall cause, directly or
     indirectly, any increase of Sublessor's insurance expense, said additional
     expense shall be paid by Sublessee to Sublessor upon demand. No such
     payment by Sublessee shall limit Sublessor in the exercise of any other
     rights or remedies, or constitute a waiver of Sublessor's right to require
     Sublessee to discontinue such act or use.
<PAGE>

7.   Notices. All notices or demands of any kind required or desired to be given
     by Sublessor or Sublessee hereunder shall be in writing and shall be deemed
     delivered forty-eight (48) hours after depositing the notice or demand in
     the United States mall, certified or registered, postage prepaid, addressed
     to the Landlord or Tenant respectively at the addresses set forth after
     their signatures at the end of this Sublease. All rent and other payments
     due under this Sublease or the Master Lease shall be made by Sublessee to
     Sublessor at the same address.

DATED: October 11, 1999
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SUBLESSOR: HRG, Inc.,                       SUBLESSEE: Synplicity, Inc.
           ----------                                  ----------------
The Human Resource Group
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By:_________________________                By: /s/ Douglas S. Miller
                                                --------------------------
    Stan Sewitch, President                      Douglas S. Miller, CFO

Address: 17055 Via del Campo, #200          Address: 935 Stewart Dr.
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         San Diego, CA 92127                         Sunnyvale, CA 94086
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Telephone:  619-673-3390                    Telephone:   408-215-6000
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The undersigned, Lessor under the Master Lease attached as Exhibit A, hereby
consents to the subletting of the Premises described herein on the terms and
conditions contained in this Sublease. This consent shall apply only to this
Sublease and shall not be deemed to be a consent to any other Sublease.

DATED: 10/18, 1999               LESSOR: WBC Rancho Bernardo Partners
       -----  ----
                                    By: /s/ [ILLEGIBLE]
                                        ------------------------

                                    Address:____________________

                                            ____________________

                                            ____________________

                                    Telephone: _________________

(If Sublessor or Sublessee is a corporation, the corporate seal must be affixed
and the authorized officers must sign on behalf of the corporation. The Sublease
must be executed by the President or a Vice President and the Secretary or
Assistant Secretary unless the Bylaws or a Resolution of the Board of Directors
shall otherwise provide, in which event the Bylaws or a certified copy of the
Resolution, as the ease may be, must be furnished).