He went on to attend the Accademia Musical Chigiana in Siena, where he had master classes with the great violinists Nathan Milstein and Franco Gulli. He also took master classes with Henryk Szeryng at the Conservatory of Geneva.
Carmignola began his performing career by successfully competing in several international competitions. Early in his career he had a break when he took over from his teacher Ferro during a tour with his ensemble, the Virtuosi di Roma, to major concert halls of Europe and the United States.
From Ferro he also derived a strong interest in the Baroque music of the early eighteenth century, particularly those of the Venetian school, which included Antonio Vivaldi. He finds the sound of the violin when set up as in the Baroque time (no chin rest, flatter bridge, gut strings, and a bow that bends outward rather than inward and hence is applied to the strings with a very different touch) to be especially charming. He prefers this set-up, rather than the mere fact that his favored instrument, a Pietro Guarneri violin, was made in Venice in 1733, during the Baroque era. Carmignola became concertmaster of the orchestra of Venice's main opera theater, the Teatro La Fenice, in 1978 and remained in that position until 1985. He has played Classical and Romantic chamber music on standard-type instruments with leading soloists and ensembles, and has appeared with major orchestras conducted by maestros of the caliber of Claudio Abbado, Peter Maag, Eliahu Inbal, and Giuseppe Sinopoli. He began working with Italian period instrument specialty groups, primarily the Sonatori de la Gioioas Musica, then with the Venice Baroque Orchestra, one of Italy's primary early music ensembles, led by Andrea Marcon, who inspired Carmignola's interest in the texts of music of this era. This has led Carmignola to do his own research into the scores and sources of the Baroque Italian violin repertory. To his performances of Vivaldi's The Four Seasons, released in 2000, he and Marcon brought new nuances to the solo part and the treatment of the thorough bass part, as well as an approach to link the concertos to the idea of the change of the seasons in Venice, specifically. On the same release, Carmignola also introduced three Vivaldi violin concertos that appear never to have been recorded before. In 2013 he recorded more late Vivaldi concertos, this time with Ottavio Dantone and Accademia Bizantia.
Carmignola is a frequent participant in leading Baroque music festivals throughout Europe, including Bruges, Vienna, Brussels, Barcelona, Salzburg, and Lucerne. In 1999, he was appointed a professor of violin at the Lucerne Hochschule für Musick, and in the 2000 summer term was a professor of music at the Accademia Musicale Chigiana. He previously was a professor of violin for ten years at the Marcello Conservatory in Venice.