| 摘要 |
A detector receiver circuit ( 2 ) for use as a wake-up detector for detecting an amplitude modulated carrier signal is described. The circuit ( 2 ) comprises: an antenna ( 4 ) for receiving the modulated carrier signal; a transistor ( 10 ), such as an FET, is connected to the antenna ( 4 ) and configured to operate as a detector of modulation of the carrier frequency. The circuit further comprises a resonator circuit ( 12 - 16 ) which is also connected to the transistor and configured such that the transistor ( 10 ) can simultaneously oscillate at substantially the modulation frequency; an oscillator quenching means ( 20 ) for periodically quenching oscillation of the transistor ( 10 ) and means ( 26, 28, 30 ) for sensing the characteristics of the build-up of oscillation to indicate the presence of a modulated carrier signal. How quickly the magnitude of oscillation of the transistor ( 10 ) builds up is dependent on whether the antenna is receiving a carrier signal which is modulated at the frequency of self-oscillation of the transistor and this is utilised to detect for the presence of a valid wake-up signal.
|
