| 摘要 |
<p>A relaxation oscillator for a transponder (102, 200, 400) capable of measuring one or more parameters (e.g., temperature, pressure) in an object (e.g., a tire, 104) and transmitting a data stream (Figures 3C, 4B) to an external reader/interrogator (106). The transpond er typically operates in a passive mode, deriving its power (Vxx, Vcc, Vdd) from an RF interrogation signal received by an antenna system (210, 410), but can also operate in a battery-powered active mode. The transponder includes memory (238, 438) for storing measurements, calibration data, programmable trim settings (436b), transponder ID and the like. Measurement readings (NT, Np) comprise counting oscillations of a measurement signal (Fosc') during a fixed time window (tW, tT, tp). The measurement signal is generated by a relaxation oscillator (252, 312, 452, 512) diriven by the alternating charging and discharging of measurement capacitors (CFX, Cp), wherein the capacitor charging rate is a function of current (a measurement current I(T)B which may be indicative of temperature), and of capacitance (which may be indicative of pressure).</p> |
