Low power implantable apparatus and method for receiving an AM signal
US4220156A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Nov 3, 1978 |
| Grant date | Sep 2, 1980 |
| Priority date | — |
| Expiry date | Nov 3, 1998 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S128/903
- WIPO fieldMedical technology
- WIPO sectorInstruments
Abstract
An implantable AM receiver having a variable threshold which can detect signals above a changing noise level. An AM receiver is provided which provides a modulation envelope corresponding to the amplitude of a pulse-modulated RF signal radiated by an external device. A voltage signal is developed which is at least equal to the amplitude of the modulation envelope, but which decays at a predetermined rate if the modulation envelope drops to a value below the voltage signal. The voltage signal is then scaled to a predetermined percentage of a value corresponding to the value of the modulation envelope, and biased so that it cannot drop below a predetermined minimum level. The scaled voltage signal comprises the variable threshold and is compared by a comparator to the modulation envelope. If it is below the modulation envelope, the comparator outputs a voltage having a first state; if it is above the modulation envelope, the comparator outputs a voltage having a second state.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.