Research has been developed in discrete-time and continuous-time, using switched-capacitor and gmC techniques, respectively.
José Gabriel Rodríguez Carneiro Gomes, "Conversor DSB/SSB a Capacitores Chaveados Usando um Transformador de Hilbert Recursivo", Master's thesis, PEE/COPPE/UFRJ, Rio de Janeiro, RJ, Brazil, June, 2000 (thesis in Portuguese).