Integratable tunable resonant circuit for use in filters and oscillators
US5949295A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | May 15, 1995 |
| Grant date | Sep 7, 1999 |
| Priority date | — |
| Expiry date | May 15, 2015 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03B2200/0036
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A circuitry arrangement for a resonant circuit that may be completely monolithically integrated and electrically tuned has a differential amplifier stage with two transistors T.sub.1,T.sub.1 ' fed by a constant current source I.sub.0 that are differentially loaded at their collectors by a voltage-dependent capacity and inductively loaded in relation to the circuit ground by a pair of emitter followers T.sub.2,T.sub.2 ' with electrically adjustable impedance that act upon the base. To implement the electrically adjustable impedances, transistors with associated resistances are provided (for example a pair of emitter followers T.sub.3,T.sub.3 ' with base pre-resistances R.sub.1,R.sub.1 ') which may be adjusted by control currents (for example I.sub.1 I.sub.1 ') . The voltage-dependant capacity is implemented by transistors T.sub.4,T.sub.4 ' whose short-circuited emitters and collectors are connected so that the circuit node thus obtained is applied to the circuit ground through a voltage source U.sub.1. This circuit arrangement may also be used in a controllable oscillator by interconnecting two resonant circuits in a loop. The output signal of the first resonant circuit is used to c…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.