Leases
 12 Months Ended
Dec. 31, 2021
Leases [Abstract]  
Leases
9.
Leases
The Company leases facilities under
non-cancellable
operating leases, which have lease terms varying from one to five years. Total lease costs for the year ended December 31, 2021 was
 
US
$
4.2 million, included in cost of revenues, research and development, sales and marketing and general and administrative expenses in the Company’s consolidated statements of comprehensive loss. Out of the total lease costs, there was
 
US$0.5
million 
of expenses for short-term leases within 12 months.
Lease term and discount rates were as follows:
 
    
As of
December 31,
2021
  
     (US$ thousand)  
Weighted-average remaining lease term
         
Operating leases
      2.0 years  
Weighted-average discount rate
         
Operating leases
      5.1 % 
    
 
 
  
Maturities of lease liabilities were as follows:
 
    
As of

December 31,
2021
  
     (US$ thousand)  
2022
     
$
 4,219  
2023
      3,019  
2024
      515  
    
 
 
  
Total undiscounted lease payments
      7,753  
Less: imputed interest
      (344 )
 
    
 
 
  
Total
prese
nt value of
lease liabilitie
s
     
$
 7,409  
    
 
 
  
 
As of December 31, 2020, future minimum payments under
non-cancellable
operating leases for office rental, office equipment and property management fee of office premises consist of the following:

 
    
Operating
Leases *
    
     (US$ thousand)    
2021
   
$
 		 2,914  
 
2022
      2,317    
2023
      1,439    
2024
      106    
    
 
 
    
    
$
 6,776    
    
 
 
    
 
*
Amounts are based on ASC 840,
 Leases
 that were superseded upon the Company’s adoption of ASC 842,
 Leases
on January 1, 2021.
Under ASC 840, rental
expense was US$1.4 million and US$2.3 million for the years ended December 31, 2019 and 2020, respectively
.