Negative Input Impedance Research Articles

Switched capacitor first order all pass circuit using two terminal negative input impedance building block

The synthesis of a switched capacitor (SC) first order ‘all pass circuit’ using an SC version of a two terminal negative impedance is presented. With appropriate signal conditioning, any desired s to Z transformation can be achieved.

Amplification by a voltage locked array of Josephson junctions

We have studied a new type of Josephson junction amplifier which is based on a two-junction array; the junctions are mutually phase locked at the Josephson self-oscillation frequency. With this frequency at 82 GHz, the voltages of the junctions remain equal (locked) for a bias current range as large as 60% of the critical current. Over a much smaller bias range, with an applied signal frequency of 1 kHz, a small-signal power gain of 19 dB was measured, accompanied by a negative resistance input impedance. This performance is consistent with a quasistatic theory of the amplifier.

Synthesis of switched-capacitor filters using FDNR-type second-order time-dependent capacitors in p-domain

A switched-capacitor (SC) version of an FDNR-like second-order time-dependent capacitor in p-domain is obtained by using two building blocks each offering two-terminal negative input impedance. The two-terminal compound block is used to illustrate the synthesis of various switched-capacitor transfer functions.

New amplifier techniques

Three new techniques in television amplifier design are discussed. These are:–(a) The Cathode Repeater.(b) Shunt-regulated Amplifiers.(c) Feedback Amplifiers with desired amplitude frequency characteristics.(a) The Cathode Repeater represents the first of three attempts to improve upon the performance of simple valve amplifiers at video frequencies and it is shown that by its use, the designer has choice of input and output impedance.(b) Shunt-regulated Amplifiers are shown to have improved athplitude linearity, higher gain, improved frequency response and greater conversion efficiency than conventional amplifiers and are particularly attractive for television modulator applications.Some types have the properties of positive, zero or negative output impedance, positive, infinite or negative input impedance, and are stabilized inherently against supply fluctuations.(c) Feedback Amplifiers with desired amplitude frequency characteristics.It is shown that by the use of complex feedback, amplifiers may have amplitude frequency response characteristics of: Aperiodic flatness; Maximal flatness; Optimal flatness.It is shown that by the application of optimal feedback, stage gains comparable with those possible with 4-terminal coupling networks are easily achieved.Practical circuits and experimental results are given for all the technupies described.