Theory and design of low-noise multipath amplifiers
Krüger, Petrus P.
De Jager, Ocker C.
MetadataShow full item record
The theoretical minimum noise measure of a multipath amplifier (an amplifier that has multiple parallel amplifiers) is achieved by using the optimum source impedance and optimum gain for each amplification path. This optimum source impedance and gain can be calculated by replacing each amplifier with its optimum source impedance. The resulting noise measure is the same as the minimum noise measure of the amplifiers used. The theory is demonstrated by applying it to distributed am plifiers. In an ideal distributed amplifier, the magnitude of the optimum gain of the amplification paths decreases and the phase delay increases the farther the stage is from the input, with the decrease in gain being faster for higher frequencies. The challenge in designing broadband low-noise distributed amplifiers is to achieve optimum gain matching over broad bandwidths. A numerical optimization procedure that separates source impedance and gain matching is proposed and demonstrated by optimizing a 0.5-2-GHz distributed amplifier. An average noise measure of 0.3 dB is achieved, which is only 0.1 dB higher than the minimum noise measure of the amplification stages used. This increase is due to transmission line loss and gain mismatch.
Showing items related by title, author, creator and subject.
Krüger, Petrus Paulus (Institution of Engineering and Technology (IET), 2012)A two-path low-noise amplifier (LNA) designed for the planned MeerKAT radio telescope is presented. The LNA has a noise figure (NF) of less than 0.36 dB and input return loss of less than 12 dB from 0.7 to 1.8 GHz. It ...
Strachan, Stefanie (2013)Cosmic-ray fluctuations are monitored by neutron monitors using several different kinds of proportional counter tubes. An important component of these monitors is the electronic subsystem that registers and counts output ...
Niemann, Andries Christiaan (North-West University, 2008)Active magnetic bearings (AMBs) have become a key technology in industrial applications with a continued drive for cost reduction and an increase in reliability. AMBs require position feedback to suspend the rotor. ...