Drawing a circle on the map

I am attempting to draw a circle with a 20km radius around the center point of my map (the location of my business). I’m trying to represent our service area.

Below is the code I have added, anyone have any idea as to why it’s not working for me?

<script type="text/javascript">
            var map_<?php echo $map_id; ?>;
            function pw_run_map_<?php echo $map_id; ?>(){

                var location = new google.maps.LatLng("<?php echo $coordinates['lat']; ?>", "<?php echo $coordinates['lng']; ?>");

                var map_options = {
                    zoom: 16,
                    center: location,
                    mapTypeId: google.maps.MapTypeId.ROADMAP
                }

                map_<?php echo $map_id ; ?> = new google.maps.Map(document.getElementById("<?php echo $map_id ; ?>"), map_options);

                var marker = new google.maps.Marker({
                    position: location,
                    map: map_<?php echo $map_id; ?>
                });

                var circle = new google.maps.Circle({
                  map: map_<?php echo $map_id; ?>
                  radius: 20000,
                  fillColor: '#AA0000'
                });

                circle.bindTo('center', marker, 'position');

            }

            pw_run_map_<?php echo $map_id; ?>();
        </script>

https://www.ads-software.com/plugins/simple-google-maps-short-code/