Bipolar high impedance element
US7230476B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Jan 18, 2005 |
| Grant date | Jun 12, 2007 |
| Priority date | — |
| Expiry date | Sep 9, 2025 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03F2203/45612
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A bipolar high impedance element comprises a p-n diode made from a compound semiconductor, and circuitry arranged to reverse-bias the diode such that the diode conducts a nearly constant current—thereby enabling the element to be employed as a high impedance element. The diode is preferably the base-emitter junction of a transistor made from a compound semiconductor like InP, such that an on-chip high impedance element is provided for a fabrication process such as that used for HBTs. The element is suitably employed in an active low pass filter design: the element is connected between an input signal and an op amp input, and a feedback capacitor is connected between the op amp's output and input. The resulting filter's time constant varies with the reverse-biased diode's impedance and the capacitance of the feedback capacitor.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.