Abstract: A rotation rate sensor which employs a built-in (i.e. internal) test circuit. The rotation rate sensor includes a piezoelectric structure. Deposited on the piezoelectric structure are at least two pickup high and two pickup low electrodes. A pickup circuit is coupled to the pickup high and pickup low electrodes. During a normal mode of operation, the piezoelectric structure is subject to a rotation about one of its axis. In response, the pickup circuit generates a rate signal which corresponds to the rotation rate of the piezoelectric structure. The test circuit is coupled to the pickup low electrodes. During a test mode of operation, the piezoelectric structure is also subject to a rotation about the axis. But, the test circuit generates at the same time a test signal which is provided to the pickup low electrodes and which corresponds to a pseudo rate of rotation.