Abstract: A watchdog circuit and method are provided for monitoring a microprocessor to detect the presence of a malfunction condition such as a program lock-up. The watchdog circuit includes a first capacitor coupled to a supply voltage and a transistor having a collector and emitter coupled in parallel with the first capacitor. The transistor has a base for receiving a signal in response to a status output signal generated by the microprocessor. A voltage threshold detector is provided for comparing a voltage potential associated with the capacitor with a predetermined threshold voltage and producing a reset signal in response thereto. The threshold voltage detector produces a small current which is utilized to charge the first capacitor. The reset signal is provided to the microprocessor to initiate a reset operation which will reset the microprocessor in an attempt to eliminate the malfunction condition.

Abstract: An electrically tuned super-regenerative receiver (10) comprises a feedback type oscillator having a signal output and a signal input, phase shift components (30) connected in a feedback loop for coupling the signal output to the signal input to cause oscillations, and a quench oscillator (35) coupled to the signal input for switching the oscillator between an oscillating and a non-oscillating condition. A variable capacitance device (40), such as a varactor diode, is connected between the signal output and a reference potential (21), and a microprocessor (105) provides a tuning voltage (42) which is applied at the signal output for varying the current in the varactor diode, thereby varying the oscillator center operating frequency. The oscillator center operating frequency is detected by a spectrum analyzer (112) and compared to a desired center operating frequency by a controller (118).