Integrated ECG-telemetry FM transmitter

An integrated transmitter incorporating inductive coupling has been developed. A modified emitter-coupled multivibrator serves as oscillator and modulator. This circuit ensures proper biasing through extensive use of active elements, and it operates over an extremely wide range of currents and parameter tolerances. Without a differential input, only two of the three normally used electrodes are needed. Advanced circuit techniques (active loads, etc.) were employed and emphasis was put on low power, low battery voltage, minimum number of external components, and small chip size. The circuit can be fabricated by standard monolithic processing techniques.