US 10,892,925 B2
Communication receiver interface for current loop circuit
Michal Brychta, Limerick (IE); Alan Patrick Cahill, Edinburgh (GB); and Sharad Vijaykumar, Bangalore (IN)
Assigned to ANALOG DEVICES INTERNATIONAL UNLIMITED COMPANY, Limerick (IE)
Filed by Analog Devices International Unlimited Company, Limerick (IE)
Filed on Nov. 16, 2018, as Appl. No. 16/193,739.
Prior Publication US 2020/0162293 A1, May 21, 2020
Int. Cl. H04L 27/148 (2006.01); H03K 19/0175 (2006.01)
CPC H04L 27/148 (2013.01) [H03K 19/017545 (2013.01)] 22 Claims
OG exemplary drawing
 
1. A current loop interface circuit configured to couple to and communicate information with an external device based on a level of current of a first current signal, the current loop interface circuit including an integrated circuit comprising:
an analog-to-digital converter;
control logic configured to enable the analog-to-digital converter to provide a multiple-bit, digital representation of the level of the current of the first current signal in a first configuration;
a complex impedance circuit configured to modulate an input impedance of the current loop interface circuit to recover a frequency shift key (FSK) signal from the first current signal, including modulating a first input impedance of the current loop interface circuit at a first frequency range of the FSK signal and a second input impedance of the current loop interface circuit at a second frequency range of a current loop signal of the first current signal, the second frequency range of the current loop signal is below the first frequency range of the of the FSK signal; and
a first node configured to couple to a FSK receiver and to provide the FSK signal recovered from the first current signal to the FSK receiver.