Novel Amplifier


STFC has developed a gain block with improved noise performance and lower power consumption, developed initially for use in a charge amplifier front end. The block can also be used in other types of amplifier, especially voltage amplifiers and shaping amplifiers.









The basic gain block in charge amplifiers have extremely high input impedance and low input bias current. It is also very fast. This is achieved by using a discrete component front end, which uses Junction field - effect transistors (JFETs) TI in common source configuration. The JFETs take the signal from the drain into the emitter of a common base bipolar stage which is arranged with high load impedance.  A voltage feedback buffer amplifier then picks off the signal and provides the drive power required to drive a load.


The new gain block developed by STFC replaces the common base stage and buffer stage with a current feedback amplifier.  Therefore the gain block consists of input and output terminals, with a non-inverting input stage connected to the input terminal. This stage has extremely high, input impedance and a current feedback amplifier. This amplifier’s inverting input is connected to the output of the input stage and its output is connected to the output terminal.


This gain block thus allows the use of a current feedback amplifier in conjunction with conventional feedback networks normally associated with voltage feedback stages. Charge amplifiers or active filters created in this way exhibit the speed, power and noise performance advantages of current feedback devices plus the simplicity and precision afforded by conventional voltage feedback networks. For example, connecting a conventional feedback network directly around a current feedback amplifier would result in wild oscillation and instability. The configuration of the present invention overcomes this difficulty.




•       Replacing common base and buffer stages with a non-inverting input stage and a current feedback amplifier stage.




•       Improved noise performance

•       Reduced power consumption




•       Particle detectors

•       Satellite and space applications

•       Telecommunications



Patent Information:
Country Serial No.
United Kingdom 0224321.0
For Information, Contact:
Elizabeth Bain
IP Manager
STFC Innovations
+44 (0) 1925 60 3680
01.a. Electronics
01.h. Imaging & Detector Technology
09.b. Amplifier, A/D Transducer