Method and circuit for reducing effects of distributed capacitance associated with large thin film resistors
US4904951A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jun 6, 1988 |
| Grant date | Feb 27, 1990 |
| Priority date | — |
| Expiry date | Jun 6, 2008 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03H7/18
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A technique for reducing phase shift of a signal passing through a large thin film resistor on an insulating layer includes applying a signal to one terminal of the thin film resistor and also to one end of an underlying doped epitaxial region. The opposite terminal of the thin film resistor is connected to a virtual ground or virtual reference voltage produced by an inverting input of an operational amplifier. The corresponding opposite end of the epitaxial layer is connected to ground or other reference voltage. The voltage gradients produced by currents flowing through both the thin film resistor and the epitaxial layer are equal, so that substantially no incremental charging current flows through capacitance between the thin film resistor and the epitaxial layer. Phase shift of the signal flowing through the thin film resistor is thereby avoided.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.