Quarterly report pursuant to Section 13 or 15(d)

Share-Based Compensation

Share-Based Compensation
9 Months Ended
Sep. 30, 2020
Share-based Payment Arrangement [Abstract]  
Share-Based Compensation Share-Based Compensation
As of September 30, 2020, we have two active share-based compensation plans, the 2018 Equity Incentive Plan and the 2011 Employee Stock Purchase Plan.
In January 2020, we granted performance stock unit (“PSU”) awards to our CEO and CFO. These PSUs fully vest on December 31, 2022 and have separate performance goals than the previously granted market stock units. We estimate fair value of performance stock unit awards based on the share price and other pertinent factors on the grant date. Compensation expense for performance stock unit awards are recognized on a straight-line basis over the requisite service period of the award based on expected achievement of the performance condition. Provided that the requisite service is rendered, the shares will become vested and payout will occur based on the outcome of the performance condition. Any unrecognized compensation cost shall be recognized when the award becomes vested.
The terms of all other awards granted during the nine months ended September 30, 2020 and the methods for determining grant-date fair value of the awards are consistent with those described in the consolidated financial statements included in our Annual Report on Form 10-K for the year ended December 31, 2019.
Details of share-based compensation expense are as follows (in thousands):
  Three Months Ended
September 30,
Nine Months Ended
September 30,
  2020 2019 2020 2019
Cost of revenue $ 79  $ 37  $ 229  $ 193 
Marketing and selling 475  270  1,424  773 
Research and development 275  161  798  600 
General and administrative 1,507  1,384  4,511  4,705 
Total $ 2,336  $ 1,852  $ 6,962  $ 6,271 

As of September 30, 2020, unrecognized compensation expense related to the unvested portion of stock options and other stock awards was approximately $13.0 million, which is expected to be recognized over a weighted average period of 2.0 years.