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| (Mark One) |
|------------|
| x          | ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d)  OF THE SECURITIES EXCHANGE ACT OF 1934 |
|       | For the fiscal year ended December 31, 2011 |
|       |   |
| Or         |
| o          | TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 |
|       | For the transition period from          to |

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| Delaware                                              | 25-1701361          |
|-------------------------------------------------------|---------------------|
| (State or Other Jurisdiction of                       | (I.R.S. Employer    |
| Incorporation or Organization)                        | Identification No.) |
|                                                  |                |
| 333 West San Carlos Street, Suite 1000 |                |
| San Jose, California                             | 95110               |
| (Address of Principal Executive Offices)              | (Zip Code)          |

| Title of each class    |   | Name of each exchange on which registered |
|---------------------------------------|--------|-------------------------------------------------------------------------|
| Common Stock, $0.00015 par value |   | The NASDAQ Stock Market LLC                                             |

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| Large accelerated filer o |   | Accelerated filer x                      |   | Non-accelerated filer o |   | Smaller reporting company o |
|--------------------------------|--------|-----------------------------------------------|--------|------------------------------|--------|----------------------------------|
|                           |   | (Do not check if a smaller reporting company) |   |                         |

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|   | 1. | This Amendment corrects the salary, severance pay, accrued paid time off at the time of termination of employment, as well as certain premiums for COBRA coverage, paid by the Company to Ms. Joy E. Leo, our former Executive Vice President, Chief Administration Officer, and acting Chief Financial Officer.  This Amendment also includes the amount received by Mr. Shahbazian, our former interim Chief Financial Officer, and Vice President, Finance, for accrued paid time off paid at the time of termination of employment.  Such information was inadvertently excluded from the Part III Form 10-K. |
|--------|----|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|

|   | 2. | This Amendment corrects the sum reflected in the “Value of the Benefit and Payment Amount Received at the Time of Resignation ($)” column in the “Potential Payment Upon Termination of Employment” table from $895,600 to $780,800.  Such sum was incorrect in the Part III Form 10-K. |
|--------|----|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|

|   | 3. | This Amendment corrects the sum reflected for Lucio Lanza, the Chairman of the Board of Directors, in the “Total ($)” column in the “Director Compensation Table.”  from $210,800 to $210, 400. Such sum was incorrect in the Part III Form 10-K. |
|--------|----|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|

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| Name & Principal Position           | Year   |   |   | Salary ($) |   |   |   | Bonus ($) |   |   |   | StockAwards($)(1) |   |   |   | OptionAwards($)(1) |   |   |   | All OtherCompensation($)(2) |   | Total ($) |
|-----------------------------------------|--------|--------|--------|------------|--------|--------|--------|-----------|--------|--------|--------|-------------------|--------|--------|--------|--------------------|--------|--------|--------|-----------------------------|--------|-----------|
|                                    |   |   |   |       |   |   |   |      |   |   |   |              |   |   |   |               |   |   |   |                        |   |      |
| Michael Shahbazian                      | 2011   |   |   | 128,950    |   |   |   | -         |   |   |   | 50,670            |   |   |   | -                  |   |   |   | 7,600                       | (6)    | 187,220   |
| Former Interim Chief Financial Officer, | 2010   |   |   | -          |   |   |   | -         |   |   |   | -                 |   |   |   | -                  |   |   |   | -                           |   | -         |
| and Vice President, Finance (5)         | 2009   |   |   | -          |   |   |   | -         |   |   |   | -                 |   |   |   | -                  |   |   |   | -                           |   | -         |
|                                    |   |   |   |       |   |   |   |      |   |   |   |              |   |   |   |               |   |   |   |                        |   |      |
|                                    |   |   |   |       |   |   |   |      |   |   |   |              |   |   |   |               |   |   |   |                        |   |      |
| Joy E. Leo                              | 2011   |   |   | 125,830    |   |   |   | -         |   |   |   | -                 |   |   |   | -                  |   |   |   | 160,070                     | (8)    | 285,900   |
| Former Executive Vice President,        | 2010   |   |   | 270,000    |   |   |   | -         |   |   |   | -                 |   |   |   | -                  |   |   |   | 200                         |   | 270,200   |
| Chief Administration Officer and        | 2009   |   |   | 270,000    |   |   |   | 89,400    | (9)    |   |   | -                 |   |   |   | 98,600             |   |   |   | 200                         |   | 458,200   |
| Acting Chief Financial Officer (7)      |   |   |   |       |   |   |   |      |   |   |   |              |   |   |   |               |   |   |   |                        |   |      |

|   | (5)  | Mr. Shahbazian was appointed as our Vice President Finance and Interim Chief Financial Officer on June 17, 2011 and  served through December 1, 2011. |
|--------|-----------|------------------------------------------------------------------------------------------------------------------------------------------------------------|

|   | (6)  | This amount includes amounts received by the executive officer for accrued paid time off paid at the time of    termination of employment. |
|--------|-----------|-----------------------------------------------------------------------------------------------------------------------------------------------------------|

|   | (7)  | Ms. Leo resigned as our Executive Vice President, Chief Administration Officer and Acting Chief Financial Officer effective June 17, 2011 |
|--------|-----------|-------------------------------------------------------------------------------------------------------------------------------------------|

|   | (8) | This amount includes the portion of then current base salary paid to Ms. Leo in connection with termination of Ms. Leo’s employment as set forth under Ms. Leo’s employment offer. This also includes the amounts received for accrued paid time off at the time of termination of employment, severance payment and the premiums for COBRA coverage paid by the Company, as set forth under Ms. Leo’s employment offer. |
|--------|-----|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|

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| ExhibitNumber |   | Description                                                                                                                                                                                            |
|---------------|--------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| 31.01         |   | Certification of principal executive officer Pursuant to Exchange Act Rules 13a-14(a) and 15d-14(a), as Adopted Pursuant to Section 302 of the Sarbanes-Oxley Act of 2002.              |
| 31.02         |   | Certification of principal finance and accounting officer Pursuant to Exchange Act Rules 13a-14(a) and 15d-14(a), as Adopted Pursuant to Section 302 of the Sarbanes-Oxley Act of 2002. |

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|   | PDF SOLUTIONS, INC. |
|--------|---------------------|
|   |                |   |
|   | By:                 | /s/ JOHN K. KIBARIAN |
|   |                | John K. Kibarian |
|   |                | President and Chief Executive Officer(principal executive officer) |
|   |                |   |
|   | By:                 | /s/ GREGORY WALKER |
|   |                | Gregory Walker |
|   |                | Vice President, Finance, and CFO(principal financial and accounting officer) |

| Date         | Signature                   | Title                                               |
|--------------|-----------------------------|-----------------------------------------------------|
|         |                        |                                                |
| May 24, 2012 |  /S/ JOHN K. KIBARIAN  | Director, President and Chief Executive Officer     |
|         | John K. Kibarian            | (principal executive officer)                       |
|         |                        |                                                |
| May 24, 2012 |  /S/ GREGORY WALKER    | Vice President, Finance and Chief Financial Officer |
|         | Gregory Walker              | (principal financial and accounting officer)        |
|         |                        |                                                |
| May 24, 2012 |  /S/ KIMON W. MICHAELS | Director, Vice President, Products and              |
|         | Kimon W. Michaels           | Solutions                                           |
|         |                        |                                                |
| May 24, 2012 | *                           | Chairman of the Board of Directors                  |
|         | Lucio L. Lanza              |                                                |
|         |                        |                                                |
| May 24, 2012 | *                           | Director                                            |
|         | R. Stephen Heinrichs        |                                                |
|         |                        |                                                |
| May 24, 2012 | *                           | Director                                            |
|         | Thomas Caulfield            |                                                |
|         |                        |                                                |
| May 24, 2012 | *                           | Director                                            |
|         | Albert Y.C. Yu              |                                                |

| *By:   | /s/  JOHN K. KIBARIAN    |   |
|--------|------------------------------------|--------|
|   | John K. Kibarian, Attorney-in-Fact |   |

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| ExhibitNumber |   | Description                                                                                                                                                                               |
|---------------|--------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| 31.01         |   | Certification of principal executive officer Pursuant to Exchange Act Rules 13a-14(a) and 15d-14(a), as Adopted Pursuant to Section 302 of the Sarbanes-Oxley Act of 2002.                |
|          |   |                                                                                                                                                                                      |
| 31.02         |   | Certification of principal financial and accounting officer Pursuant to Exchange Act Rules 13a-14(a) and 15d-14(a), as Adopted Pursuant to Section 302 of the Sarbanes-Oxley Act of 2002. |