Low voltage analog front end
US5859558A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Apr 11, 1997 |
| Grant date | Jan 12, 1999 |
| Priority date | — |
| Expiry date | Apr 11, 2017 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03D2200/0043
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A low voltage analog front end (AFE) includes a differential transistor pair which converts an input voltage, typically A.C.-coupled to the pair's control inputs, to a differential current. Impedance networks connected to each transistor's control input are joined together at a common node, and a current source is connected to the node which causes DC bias currents to be mirrored through the pair's current circuits, so that the AFE's differential output current comprises a differential current produced by the pair in response to an input voltage and superimposed on the DC bias currents. The current source preferably generates mirrored currents which are larger than its reference current to linearize the pair's response and to provide the AFE with a wide dynamic range. An input to the AFE sees a low impedance which is about equal to the sum of the impedance networks, which can be resistive or complex as needed. The AFE has widespread application as a front end circuit, serving as a low voltage input stage for a Gilbert mixer, for example. By generating bias currents via the pair's control inputs, supply voltage headroom requirements are reduced, improving a system's dynamic range an…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.