Band-gap reference circuit for biasing an RF device
A voltage reference circuit implemented in GaAs to provide an output voltage component proportional to absolute temperature is described herein. The various embodiments of the voltage reference circuit described here can be used to provide precision voltage to bias a RF device. The voltage reference circuit can be provided on the same die as the RF device. The various embodiments described herein can be implemented in a GaAs material system.
1. A voltage reference circuit, comprising:
a precision voltage generator including a plurality of transistors and configured to provide an output voltage having a first component that depends on a band-gap of the plurality of transistors and a second component that is proportional to absolute temperature, the plurality of transistors including a first bipolar transistor and a second bipolar transistor, a base of the second bipolar transistor connected to a base of the first bipolar transistor;
an enable circuit configured to selectively enable the precision voltage generator based on a voltage of an enable terminal; and
a mode-control circuit operatively associated with the precision voltage generator and configured to selectively operate the precision voltage generator in a low power mode based on a voltage of an input terminal.
2. The voltage reference circuit of claim 1 wherein the plurality of transistors of the precision voltage generator further includes a field effect transistor (FET), a source of the FET connected to the base of the first bipolar transistor and to the base of the second bipolar transistor, a collector of the first bipolar transistor connected to a gate of the FET.
3. The voltage reference circuit of claim 1 wherein the voltage reference circuit is implemented in a gallium arsenide (GaAs) semiconductor die.
4. An apparatus comprising:
a voltage reference circuit configured to generate an output voltage having a component proportional to absolute temperature;
a current mirror circuit configured to receive the output voltage and to generate a bias voltage for inputting to a RF device; and
a mirror shut-off circuit configured to selectively enable the current mirror circuit based on a voltage of an enable terminal, the mirror shut-off circuit including a bipolar transistor having a base connected to the enable terminal, a FET, a first FET current source, and a second FET current source, a source of the first FET current source and a drain of the second FET current source connected to a gate of the FET.
5. The apparatus of claim 4 wherein the voltage reference circuit, the current mirror circuit, and the mirror shut-off circuit are implemented in a GaAs semiconductor die.
6. A module incorporating the GaAs semiconductor die of claim 5 .
7. The apparatus of claim 4 wherein a drain of the first FET current source is connected to the enable terminal.
8. The apparatus of claim 7 wherein the mirror shut-off circuit is configured to turn off the current mirror circuit when the voltage of the enable terminal is equal to or less than approximately 1 V.
9. The apparatus of claim 4 wherein the voltage reference circuit includes a first bipolar transistor and a second bipolar transistor, a base of the second bipolar transistor connected to a base of the first bipolar transistor.
10. The apparatus of claim 9 wherein the voltage reference circuit further includes a FET, a source of the FET connected to the base of the first bipolar transistor and to the base of the second bipolar transistor, and a collector of the first bipolar transistor connected to a gate of the FET.
11. The apparatus of claim 10 wherein the voltage reference circuit provides the output voltage on an output terminal, the voltage reference circuit further including a resistor connected between the output terminal and the gate of the FET.
12. A semiconductor die comprising:
a voltage reference circuit including a plurality of transistors and configured to provide an output voltage having a first component that depends on a band-gap of the plurality of transistors and a second component that is proportional to absolute temperature;
a current mirror circuit configured to generate a bias voltage based on the output voltage from the voltage reference circuit;
a mirror shut-off circuit configured to selectively enable the current mirror circuit based on a voltage of an enable terminal, the mirror shut-off circuit including a bipolar transistor having a base connected to the enable terminal, a FET, a first FET current source, and a second FET current source, a source of the first FET current source and a drain of the second FET current source connected to a gate of the FET; and
a RF device configured to receive the bias voltage from the current mirror circuit.
13. The semiconductor die of claim 12 implemented in GaAs semiconductor material.
14. The semiconductor die of claim 12 further comprising a master enable circuit configured to enable or disable the voltage reference circuit.
15. A mobile device comprising:
a transmitter for generating an radio frequency (RF) signal;
an antenna configured to direct the generated RF signal out of the mobile device; and
a semiconductor module configured to receive the RF signal from the transmitter, the semiconductor module including a switch and a GaAs die connected to the switch, the GaAs die having a voltage reference circuit configured to provide an output voltage having a component proportional to absolute temperature, the semiconductor module further including a current mirror circuit configured to receive the output voltage and a mirror shut-off circuit configured to selectively enable the current mirror circuit based on a voltage of an enable terminal, the semiconductor module configured to condition the RF signal and to transmit the RF signal to the antenna, the mirror shut-off circuit including a bipolar transistor having a base connected to the enable terminal, a FET, a first FET current source, and a second FET current source, a source of the first FET current source and a drain of the second FET current source connected to a gate of the FET.
16. The mobile device of claim 15 wherein the semiconductor module includes a single GaAs die.
17. The mobile device of claim 15 wherein the semiconductor module does not include a complementary metal-oxide (CMOS) die.
18. The mobile device of claim 17 wherein the semiconductor module is configured to condition the signal at least in part via amplification of the signal.
19. The mobile device of claim 15 wherein the voltage reference circuit includes a first bipolar transistor and a second bipolar transistor, a base of the second bipolar transistor connected to a base of the first bipolar transistor.
20. The mobile device of claim 19 wherein the voltage reference circuit further includes a FET, a source of the FET connected to the base of the first bipolar transistor and to the base of the second bipolar transistor, and a collector of the first bipolar transistor connected to a gate of the FET.