Title :
A novel programmable gain amplifier
Author :
O´Donoghue, G. ; Mallinson, M. ; Holloway, P.
Author_Institution :
Analog Devices Inc., Wilmington, MA, USA
Abstract :
A MOSFET input amplifier with variable gain from 0 to 42 dB and fixed bandwidth at all closed-loop gains is described. Designed for a system where phase match at all gains is the dominant design goal, this amplifier adapts its open-loop gain crossover point to keep a constant closed-loop gain. This is done by controlling an active matrix of PMOS input devices which simultaneously achieves the constant phase characteristic and optimizes the noise and offset performance. Eight such amplifiers are implemented on a single chip with more than 100 dB of isolation between each amplifier and a power supply rejection ratio (PSRR) of more than 70 dB from 0 to 30 kHz
Keywords :
CMOS integrated circuits; application specific integrated circuits; operational amplifiers; 0 to 30 kHz; 0 to 42 dB; 100 dB; MOSFET input amplifier; PMOS input devices; PSRR; active matrix; closed-loop gains; constant closed-loop gain; constant phase characteristic; fixed bandwidth; high isolation between amplifiers; isolation between each amplifier; phase match; power supply rejection ratio; programmable gain amplifier; Application specific integrated circuits; Art; Bandwidth; Design methodology; Feedback; Frequency; Gain; MOSFET circuits; Open loop systems; Operational amplifiers;
Conference_Titel :
ASIC Seminar and Exhibit, 1990. Proceedings., Third Annual IEEE
Conference_Location :
Rochester, NY
DOI :
10.1109/ASIC.1990.186148
