Capacitively-coupled amplifier with improved low frequency response
US5392001A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Feb 28, 1994 |
| Grant date | Feb 21, 1995 |
| Priority date | — |
| Expiry date | Feb 28, 2014 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03F1/083
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A capacitively-coupled amplifier circuit includes an amplifier for receiving an input signal via a coupling capacitance and for amplifying the input signal to produce an output signal. A resistor provides a bias voltage to the amplifier. The resistor is bootstrapped using positive feedback with a loop gain of slightly less than one. The bootstrapping causes an increase in the value of the resistor to lower the cut-in (pole) frequency of the amplifier. The bootstrapping or feedback circuit includes a roll-off (pole) at a frequency below the roll-off (pole) frequency of the amplifier. This prevents phase shift in the feedback loop from adversely effecting the high frequency response of the amplifier. The resulting amplifier circuit exhibits a wide passband and excellent low frequency response despite having a capacitively coupled input signal.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.