GPS receiver with reflection amplifiers
View Patent ↗An AM receiver incorporates an antenna, a transistor, a current source, and a power supply. The antenna is connected to a gate electrode of the transistor and through a link to a signal earth. In operation, the antenna receives radiation and generates a corresponding input signal which propagates to the gate electrode. The transistor is operable to process the input signal in two steps, namely to reflectively amplify the input signal to generate a correspondingly reflectively amplified input signal at the gate electrode in a first step, and amplitude demodulate the amplified input signal in a second step. The transistor is operable in a non-linear region of its current/voltage characteristic whereas it simultaneously provides reflective amplification and signal demodulation, namely the two steps occur simultaneously. In contradistinction, conventional demodulators employing gain devices operating non-linearly to provide amplitude demodulation incorporate the devices configured to function as transmission amplifiers.
1. A GPS receiver, comprising:
an antenna configured to receive an input signal;
a first amplifier configured to amplify the input signal, wherein the amplifier includes a terminal that presents a negative resistance to the input signal and thereby reflectively amplifies the input signal;
a splitter configured to receive the amplified input signal and split the signal into a plurality of split signals;
second amplifiers configured to selectively amplify or attenuate the plurality of split signals, each second amplifier including a first terminal that presents a negative resistance to at least one of the plurality of split signals and a second terminal that receives a control signal that controls the reflective amplification or attenuation of the respective split signal; and
processing circuitry configured to demodulate the amplified or attenuated split signals and calculate positional data.
2. The GPS receiver of claim 1 , further comprising a filter having a first terminal that receives the input signal from the antenna, a second terminal that communicates the input signal to and from the first amplifier, and a third terminal that outputs the amplified input signal to the splitter.
3. The GPS receiver of claim 2 , wherein the filter incorporates a thin layer of yttrium iron garnet (YIG) deposited onto an aluminum or quartz substrate that provides a signal propagation path therethrough.
4. The GPS receiver of claim 1 , further comprising a surface acoustic wave (SAW) filter configured to receive and filter a split signal that is output from the splitter.
5. The GPS receiver of claim 4 , wherein the SAW filter is configured to receive the split signal after the split signal has been selectively amplified or attenuated by a respective second amplifier.
6. The GPS receiver of claim 4 , wherein the SAW filter is operable to delay the split signal that is propagating therethrough.
7. The GPS receiver of claim 4 , wherein the SAW filter is operable to bandpass filter the split signal that is propagating therethrough.
8. The GPS receiver of claim 1 , wherein the processing circuitry includes a transistor that is configured to receive and demodulate a split signal that has been selectively amplified or attenuated by a respective second amplifier.
9. The GPS receiver of claim 8 , wherein the transistor is biased to simultaneously operate as a reflection amplifier for reflectively amplifying the split signal and as a detector for generating a demodulated signal from the split signal.
10. The GPS receiver of claim 8 , further comprising a measurement unit that receives the demodulated signal, wherein the measurement unit is further configured to generate the control signal received by each of the second amplifiers.
11. The GPS receiver of claim 1 , wherein the control signal for each of the second amplifiers is configured to cause the second amplifier to gate the respective split signal such that the split signal has a prominent amplitude when the split signal correlates with the control signal.
12. The GPS receiver of claim 1 , wherein the control signal for each of the second amplifiers is configured to control whether the second amplifier reflectively amplifies or attenuates the respective split signal.
13. The GPS receiver of claim 1 , wherein the antenna is a circularly polarized antenna.
14. The GPS receiver of claim 1 , wherein the GPS receiver is fabricated in a gallium arsenide (GaAs) microwave monolithic integrated circuit.
15. The GPS receiver of claim 1 , wherein the split signals respectively represent an early, on time, and late version of the input signal.
16. A method for processing a signal that is usable in determining a positional reference, comprising:
receiving an input signal from a source of known position;
splitting the input signal into a plurality of split signals;
for each split signal,
reflectively amplifying or attenuating the split signal with an amplifier that presents a negative resistance to the split signal, wherein the reflective amplification or attenuation of the split signal is controlled by a control signal, and
demodulating the amplified or attenuated split signals; and
processing the demodulated signals in a measurement unit to calculate positional data.
17. The method of claim 16 , further comprising amplifying the input signal with a first amplifier that presents a negative resistance to the input signal and thereby reflectively amplifies the input signal prior to splitting the signal.
18. The method of claim 16 , further comprising filtering the input signal with a magnetostatic surface wave device.
19. The method of claim 16 , further comprising filtering at least one of the split signals using a surface acoustic wave (SAW) filter.
20. The method of claim 19 , wherein the filtering includes delaying the split signal that is propagating through the filter.
21. The method of claim 16 , wherein demodulating the amplified or attenuated split signals comprises, for each split signal:
biasing a transistor to simultaneously operate as a reflection amplifier that reflectively amplifies the split signal and as a detector that generates a demodulated signal from the split signal, and
providing the split signal to the transistor.
22. The method of claim 16 , further comprising operating the measurement unit to generate the control signal for each of the amplifiers that reflectively amplify or attenuate the split signals.
23. The method of claim 16 , wherein the control signal for each of the amplifiers is configured to gate the split signal provided to the amplifier such that the split signal has a prominent amplitude when the split signal correlates with the control signal at the respective amplifier.
24. The method of claim 16 , wherein the split signals respectively represent an early, on time, and late version of the input signal.