How to cast an ObservableCollection?

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C#

Good Morning.

I have the following problem:

I got a SaveData class which should serialize an ObservableCollection<personmodel> to a XML document.
The ViewModel contains this collection while PersonModel is Model class.
I can not reference the Model in the SaveData class because this would cause an infinite dependency.

When I invoke the SerializeData() method in the ViewModel it says that it can not assign the ObservableCollection<personmodel> to the parameter type ObservableCollection<object>.
Seems logical...but how is it possible to cast the ObservableCollection?

Code for the SaveData class:

public class SaveData
{
    private XmlSerializer serializer;
    private string saveLogPath;

    public SaveData()
    {
        serializer = new XmlSerializer(typeof(ObservableCollection<object>));
    }

    private string GetSaveLogPath()
    {
        const string saveLog = "SaveLog.xml";
        var dir = AppDomain.CurrentDomain.BaseDirectory+saveLog;
        return dir;
    }

    public void SerializeData(ObservableCollection<object> dataToSerialize)
    {
        saveLogPath = GetSaveLogPath();

        if (File.Exists(saveLogPath))
        {
            var stream = new FileStream(saveLogPath, FileMode.Open);
            serializer.Serialize(stream,dataToSerialize);
        }
        else
        {
            File.Create(saveLogPath);
            var stream = new FileStream(saveLogPath, FileMode.Open);
            serializer.Serialize(stream, dataToSerialize);
        }
    }
}

Code for the ViewModel:

class MainWindowViewModel : INotifyPropertyChanged
{
     private ObservableCollection<PersonModel> personList;

     public MainWindowViewModel()
     {
          personList = new ObservableCollection<PersonModel>();
     }

     public void SaveData(object parameter)
        {
            serializer = new SaveData();
            serializer.SerializeData(PersonList); //Error Occurs here
        }
}

Any help is appreciated.
Thanks in advance.