Electrical transmission or interconnection systems – Nonlinear reactor systems – Parametrons
Patent
1980-07-17
1982-12-28
Mullins, James B.
Electrical transmission or interconnection systems
Nonlinear reactor systems
Parametrons
330264, 331 25, H03K 1940
Patent
active
043663982
DESCRIPTION:
BRIEF SUMMARY
DESCRIPTION
1. Technical Field
This invention relates to an amplifier circuit, and in more detail to an amplifier circuit wherein a couple of inverters are cascade-connected and the second inverter is biased so that the highest gain is obtained, by connecting the input and output terminals of the first inverter through a resistor (including the case where resistance is zero).
2. Background Art
A conventional amplifier circuit using a couple of inverters is shown in FIG. 1.
In FIG. 1, an input signal at the input terminal T.sub.I is applied to the input of inverter I.sub.1 via the capacitor C.sub.1. The input and output terminals of inverter I, are connected via the resistor R.sub.1. The output of the inverter I.sub.1 is provided to the terminal T.sub.0 via the inverter I.sub.2.
The relation between the input and output of each inverter forming such an amplifier circuit is shown in FIG. 2.
In FIG. 2, A shows the relation between the input V.sub.I-1 and output V.sub.O-1 of the inverter I.sub.1. The input-output characteristic A of the inverter I.sub.1 is generally expressed by a straight line since a negative feedback loop is formed for the inverter I.sub.1. Particularly, when the resistance R.sub.1 is zero (0), V.sub.I-1 becomes equal to V.sub.O-1, and the characteristic A becomes a straight line having inclination of 45.degree.. On the other hand, B shows the relation between the input V.sub.I-2 and output V.sub.O-2 of the inverter I.sub.2. The gain of inverter I.sub.2 is very high since it has no feedback loop. As is apparent from the FIG. 1, V.sub.O-1 equals V.sub.I-2.
A point C at the intersection of both characteristics of A and B indicates the bias point of the input of the inverter I.sub.2, and it is shown that the point C is set to the center of the characteristic B where the highest gain can be obtained by making the resistance R.sub.1 zero. Therefore, a large variation in the output V.sub.O-2 can be extracted from a small change of the input V.sub.I-1. As explained above, an amplifier circuit can be realized wherein the inverter is used in such a condition that the gain becomes the maximum. The same characteristics can easily be provided for both inverters, for example when CMOS is used, by making the gain constants .beta. of the inverters equal. By the way, fantastic progress in the manufacturing technology of semiconductor devices has promoted high integration of semiconductor elements to such a degree that circuits having different functions which previously had been formed on individual semiconductor chips are now formed on the same semiconductor chip.
For example, consider the integrated circuits which might be used in a car radio receiver and timer (particularly a digital clock) which are mounted in a vehicle. A car radio receiver may include a phase locked loop (generally called PLL) circuit for tuning, and this PLL circuit has a frequency divider which converts an oscillation signal sent from a crystal controlled oscillator to the desired frequency and an input amplifier circuit having the aforementioned construction in order to generate a local oscillation signal.
Formation of the PLL circuit composed of circuits having different functions onto the same semiconductor chip facilitates the manufacture of a car radio.
On the other hand, a clock also requires a crystal controlled oscillator to generate a stabilized oscillation frequency and a divider for obtaining the desired frequency signal, in order to sequentially operate a counter.
Thus total construction can be simplified by using the crystal controlled oscillator and a part of the divider in common for both a car radio and the clock.
But, there is a large difference in how car radios and clocks are used. A car radio, for example, is switched on when the driver or other person desires to listen to a radio program, and is switched off when he is going to leave the car. On the other hand, a clock must always operate without relation to the driver or other person's attendance, and it is glanced at only for convenience when one desires to
REFERENCES:
patent: 4201945 (1980-05-01), Ohgishi et al.
Fujitsu Limited
Mullins James B.
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