Dependency property converter

 <Grid>
     <Grid.Resources>
         <converter:UnitConverter x:Key="UnitConverter" ObservableUnit="{Binding ObsUnit}"/>
     </Grid.Resources>
 </Grid>

 <Grid>
     <Grid.Resources>
         <converter:UnitConverter x:Key="UnitConverter" ObservableUnit="{Binding ObsUnit}"/>
     </Grid.Resources>
 </Grid>

public class UnitConverter : DependencyObject, IValueConverter
{
    #region Properties
    public ObservableUnit ObservableUnit
    {
        get => (ObservableUnit)GetValue(ObservableUnitProperty);
        set => SetValue(ObservableUnitProperty, value);
    }
    #endregion

    #region Fields
    public static readonly DependencyProperty ObservableUnitProperty =
    DependencyProperty.Register("ObservableUnit", typeof(ObservableUnit), typeof(UnitConverter));
    #endregion
}

public class UnitConverter : DependencyObject, IValueConverter
{
    #region Properties
    public ObservableUnit ObservableUnit
    {
        get => (ObservableUnit)GetValue(ObservableUnitProperty);
        set => SetValue(ObservableUnitProperty, value);
    }
    #endregion

    #region Fields
    public static readonly DependencyProperty ObservableUnitProperty =
    DependencyProperty.Register("ObservableUnit", typeof(ObservableUnit), typeof(UnitConverter));
    #endregion
}