Single Low-voltage Supply Research Articles

Refractory WNx/W Self-Aligned Gate GaAs Power Metal-Semiconductor Field-Effect Transistor for 1.9-GHz Digital Mobile Communication System Operating with a Single Low-Voltage Supply

We have developed a refractory WNx /W self-aligned gate GaAs power metal-semiconductor field-effect transistor (MESFET) for use in L-band digital mobile communication systems. This power MESFET operates with high efficiency and low distortion at a gate bias of 0 V and a low drain bias of 2.7 V, because of its small drain knee voltage, high transconductance and sufficient breakdown voltage. This power MESFET is quite promising for a highly efficient linear power amplifier IC operating with a single low-voltage supply. Good output characteristics of the power MESFET with 1 mm gate width were attained for π/4-shifted quadrature phase shift keying (QPSK) modulated input signals in the 1.9-GHz band, such as an output power of 18.4 dBm, a power gain of 19.0 dB and a high power-added efficiency of 26.4% when a sufficiently low adjacent channel leakage power of -58 dBc was obtained.

A single-chip ADM LSI CODEC

This paper describes the circuit design of an ADM (adaptive delta modulation) LSI CODEC with filters. The LSI chip is mounted in a 16-pin DIP and can operate with single low voltage supply. In order to realize a low power dissipation LSI IC, switched capacitor technology was used in the design of input/output filters and integrators, and C-array D/A converters and low voltage analog circuits were developed. An operational amplifier with a complementary differential input stage and a comparator with a capacitor-coupled input stage were employed to obtain a wide input voltage range with a low voltage supply. This CODEC achieves speech quality higher than that of 6-bit μ-law PCM CODEC at 32 kbits/s and power dissipation of below 30 mW.

A Single-Chip ADM LSI CODEC

This paper describes the circuit design of an ADM (adaptive delta modulation) LSI CODEC with filters. The LSI chip is mounted in a 16-pin DIP and can operate with single low voltage supply. In order to realize a low power dissipation LSI IC, switched capacitor technology was used in the design of input/output filters and integrators, and C-array D/A converters and low voltage analog circuits were developed. An operational amplifier with a complementary differential input stage and a comparator with a capacitor-coupled input stage were employed to obtain a wide input voltage range with a low voltage supply. This CODEC achieves speech quality higher than that of 6-bit µ-law PCM CODEC at 32 kbits/s and power dissipation of below 30 mW.

A multipurpose transformer unit.

Some manufacturers and distributors of diagnostic instruments would lead physicians to believe that each new electrical device requires its own specially designed voltage adapter or transformer. However, since most hand instruments operate on 1.5 to 12 volts and draw a current of from 0.2 to 2.5 amp., it seemed quite feasible to construct a single low-voltage supply that could serve all of the instruments the average practitioner might use in his office. The valuable features of a small portable transformer developed recently 1 have been combined with a number of new improvements, in order to provide a maximum of convenience and safety. The final unit is shown in the figure. Four sets of outlets are provided on the front panel, two pairs with an output of 3 volts or less, one pair for 6-volt instruments, and one pair for 12 volts. The outlet jacks are color-coded green, yellow, and red,