A new integrable composite circuit with improved FET-like characteristics
A new composite circuit comprising five active devices (a JFET and four bipolar transistors) and three passive resistors is described and shown to exhibit FET-like characteristics with much improvement in thermal stability and transfer curve linearity over a wide range of input bipolar voltage. The input resistance of the proposed circuit is, however, equal to that of the FET with the additional advantage that it continues to be high even for positive input voltage. The proposed structure is fully compatible with silicon integrated circuit (IC) technology and may thus be commercially mass-produced as a three-terminal device with its terminals designated as gate, drain, and source.
Experimental Analysis of the Variants of UBCT AmplifierCircuit
The Unipolar-Bipolar Composite Transistor (UBCT) circuit is designed to combine the advantages of high input resistance of unipolar transistor and transfer curve linearity of bipolar transistor. The Composite Circuit has been designed with n-channel JFET, npn BJT and a pair of resistors, therefore, this type of JFET-BJT composite transistor is classified as UBCT. This UBCT circuit exhibits enhanced static and dynamic performances as compared to that of JFET. In the present correspondence, the performances of the variants of the UBCT amplifier circuit have been experimentally analysed on the basis of power dissipation level and the corresponding voltage gain of the amplifier. According to the experimental results, the UBCT amplifier circuit can be used as a power efficient small signal amplifier for analog applications.
Some techniques for precision monolithic circuits applied to an instrumentation amplifier
Precision monolithic circuit functions can be fabricated if proper circuit and processing techniques are incorporated. Compatible thin-film-on- silicon technology is coupled with annealing of individual resistors with a focused laser beam to provide a means for fabricating monolithic circuits in the 0.1 to 1.0 percent accuracy range. It is shown that special circuit techniques, which accommodate uniquenesses of available monolithic devices, must be used to obtain optimum circuit performance. The design of an instrumentation amplifier that incorporates emitter feedback and direct compensation of dc errors is described, together with test results that validate the techniques discussed.